chore(aur): update packages to 3.7.0

chore(release): 3.7.0

.github/ISSUE_TEMPLATE/config.yml

@@ -3,6 +3,9 @@ contact_links:
   - name: Security vulnerability
     url: https://github.com/narrrl/proton-drive-linux/security/advisories/new
     about: Report privately — never in a public issue.
+  - name: Troubleshooting and FAQ
+    url: https://github.com/narrrl/proton-drive-linux/wiki/Troubleshooting
+    about: Fixes for common problems, and what to include in a bug report.
   - name: Known issues
     url: https://github.com/narrrl/proton-drive-linux/blob/main/docs/BUGS.md
     about: The authoritative ledger of tracked bugs and their status.

.github/PULL_REQUEST_TEMPLATE.md

@@ -21,6 +21,7 @@ cargo test --workspace --locked
 - [ ] Touches recovery, staging, or anything that can be the only copy of user data
 - [ ] Changes packaging, the systemd unit, or desktop entries
 - [ ] Changes the control protocol (daemon and front ends updated together)
+- [ ] Adds or renames a page in `docs/` (listed in `SECTIONS` in `scripts/publish-wiki.sh`, which publishes it to the wiki)
 - [ ] None of the above
 
 <!-- Screenshots for GTK changes. -->

.github/workflows/ci.yml

@@ -45,7 +45,7 @@ jobs:
         run: cargo fmt --all -- --check
 
       - name: Lints
-        run: cargo clippy --workspace --all-targets -- -D warnings
+        run: cargo clippy --workspace --all-targets --locked -- -D warnings
 
       - name: Unit tests
         run: cargo test --workspace --locked
@@ -66,8 +66,9 @@ jobs:
 
   # The seeded simulation runs (docs/TESTING.md): real FUSE
   # daemons against an in-memory Drive, so they need /dev/fuse but no account.
+  # They run on pull requests too: most data-loss fixes are only exercised
+  # here, and a change that breaks one should not reach main first.
   simulation:
-    if: github.event_name != 'pull_request'
     runs-on: ubuntu-24.04
     timeout-minutes: 30
 

.github/workflows/copr.yml

@@ -0,0 +1,66 @@
+name: COPR
+
+on:
+  # Called by release.yml once the GitHub release and its assets exist: COPR
+  # downloads the tag archive and the vendored crates from the release.
+  workflow_call:
+    inputs:
+      version:
+        required: true
+        type: string
+    secrets:
+      COPR_CONFIG:
+        required: true
+  workflow_dispatch:
+    inputs:
+      version:
+        description: 'Release to build, such as 3.5.0. It must already have its vendor tarball.'
+        required: true
+        type: string
+
+permissions:
+  contents: read
+
+concurrency:
+  group: copr
+  cancel-in-progress: false
+
+jobs:
+  build:
+    name: Build in COPR
+    runs-on: ubuntu-24.04
+    container: fedora:latest
+    env:
+      VERSION: ${{ inputs.version }}
+      COPR_PROJECT: narl-rs/proton-drive-linux
+
+    steps:
+      - name: Install packaging tools
+        run: dnf -y install copr-cli rpm-build rpmdevtools
+
+      - name: Checkout repository
+        uses: actions/checkout@v7
+
+      - name: Configure COPR access
+        env:
+          COPR_CONFIG: ${{ secrets.COPR_CONFIG }}
+        run: |
+          install -d -m700 ~/.config
+          printf '%s\n' "$COPR_CONFIG" > ~/.config/copr
+          chmod 600 ~/.config/copr
+
+      # COPR rebuilds the source package without our --define, so the version
+      # has to be written into the spec itself.
+      - name: Build the source package
+        run: |
+          version="${VERSION#v}"
+          spec=packaging/proton-drive-linux.spec
+          sed -i -E "s/^(%\{!\?version: %global version )[^}]*\}/\1${version}}/" "$spec"
+          grep -qF "%global version ${version}}" "$spec"
+          mkdir -p rpmbuild/SOURCES
+          spectool -g -C rpmbuild/SOURCES "$spec"
+          rpmbuild -bs --define "_topdir $PWD/rpmbuild" "$spec"
+
+      # Waits for the build, so a failed COPR build fails this job.
+      - name: Submit to COPR
+        run: copr-cli build "$COPR_PROJECT" rpmbuild/SRPMS/*.src.rpm

.github/workflows/nix.yml

@@ -0,0 +1,59 @@
+name: Nix
+
+# Builds the flake (docs/INSTALL.md#nixos-flake) whenever its recipe, the lock
+# files or the code change, so a NixOS user's `nix build` keeps working. Run it
+# from the Actions tab for any branch to get a build to try.
+on:
+  push:
+    paths:
+      - 'flake.nix'
+      - 'flake.lock'
+      - 'packaging/nix/**'
+      - 'Cargo.lock'
+      - 'Cargo.toml'
+      - 'crates/**'
+      - 'po/**'
+      - '.github/workflows/nix.yml'
+  pull_request:
+    paths:
+      - 'flake.nix'
+      - 'flake.lock'
+      - 'packaging/nix/**'
+      - 'Cargo.lock'
+      - '.github/workflows/nix.yml'
+  workflow_dispatch:
+
+permissions:
+  contents: read
+
+concurrency:
+  group: nix-${{ github.ref }}
+  cancel-in-progress: true
+
+jobs:
+  build:
+    runs-on: ubuntu-24.04
+    steps:
+      - uses: actions/checkout@v7
+
+      - uses: cachix/install-nix-action@v31
+
+      # Pulls from the project's binary cache, and pushes what this run built
+      # when the token is there; a fork's pull request has none and only pulls.
+      - uses: cachix/cachix-action@v17
+        with:
+          name: proton-drive-linux
+          authToken: ${{ secrets.CACHIX_AUTH_TOKEN }}
+
+      - name: Check the flake
+        run: nix flake check --print-build-logs --no-build
+
+      - name: Build the package
+        run: nix build --print-build-logs .#proton-drive-linux
+
+      - name: Smoke test
+        run: |
+          ./result/bin/pdfs --version
+          for bin in pdfs-app pdfs-tray pdfs-prompt; do test -x "result/bin/$bin"; done
+          grep -q "ExecStart=$(readlink -f result)/bin/pdfs" result/lib/systemd/user/proton-drive.service
+          ls result/share/locale/*/LC_MESSAGES/pdfs.mo

.github/workflows/release.yml

@@ -52,8 +52,10 @@ jobs:
           tag_version="${GITHUB_REF_NAME#v}"
           manifest_version="$(sed -n 's/^version = "\([^"]*\)"/\1/p' Cargo.toml | head -n1)"
           pkgbuild_version="$(sed -n 's/^pkgver=//p' packaging/PKGBUILD | head -n1)"
+          spec_version="$(sed -n 's/^%{!?version: %global version \([^}]*\)}/\1/p' packaging/proton-drive-linux.spec)"
           test "$tag_version" = "$manifest_version"
           test "$tag_version" = "$pkgbuild_version"
+          test "$tag_version" = "$spec_version"
 
       - name: Release quality gates
         run: |
@@ -129,6 +131,12 @@ jobs:
           # Create tarball
           tar -czf proton-drive-linux-${{ env.VERSION }}-x86_64.tar.gz -C dist/binaries .
 
+      # Every crate the build needs, so COPR can build the spec without network.
+      - name: Package vendored crates (.tar.xz)
+        run: |
+          cargo vendor --locked dist/vendor > /dev/null
+          tar -cJf proton-drive-linux-vendor-${{ env.VERSION }}.tar.xz -C dist vendor
+
       - name: Package Debian package (.deb)
         run: |
           mkdir -p deb/DEBIAN
@@ -153,6 +161,9 @@ jobs:
           cp LICENSE deb/usr/share/licenses/proton-drive-linux/
           po/build.sh deb/usr/share/locale
 
+          # Stops the running daemon before removal, so the mount stops mirroring deletes
+          install -m755 packaging/deb/prerm deb/DEBIAN/prerm
+
           # Calculate Installed-Size in KB for the control file
           INSTALLED_SIZE=$(du -sk deb | cut -f1)
 
@@ -227,27 +238,75 @@ jobs:
           path: |
             *.deb
             *.tar.gz
+            *.tar.xz
             *.rpm
           if-no-files-found: error
 
+  # The flake is the Nix release: a tag is what `github:narrrl/proton-drive-linux/vX.Y.Z`
+  # pins, so it has to build before the release is announced.
+  nix:
+    name: Build the Nix package
+    runs-on: ubuntu-24.04
+    steps:
+      - uses: actions/checkout@v7
+
+      - uses: cachix/install-nix-action@v31
+
+      # Pulls from the project's binary cache, and pushes what this run built
+      # when the token is there; a fork's pull request has none and only pulls.
+      - uses: cachix/cachix-action@v17
+        with:
+          name: proton-drive-linux
+          authToken: ${{ secrets.CACHIX_AUTH_TOKEN }}
+
+      - name: Build the flake
+        run: nix build --print-build-logs .#proton-drive-linux
+
+      - name: Check the version
+        run: |
+          built="$(./result/bin/pdfs --version)"
+          echo "$built"
+          case "$GITHUB_REF" in
+            refs/tags/v*) grep -qF "${GITHUB_REF_NAME#v}" <<< "$built" ;;
+          esac
+
   publish:
     name: Create GitHub Release
-    needs: [checks, build-release]
+    needs: [checks, build-release, nix]
     if: startsWith(github.ref, 'refs/tags/')
     runs-on: ubuntu-24.04
 
     steps:
+      - name: Checkout
+        uses: actions/checkout@v7
+
       - name: Download packages
         uses: actions/download-artifact@v8
         with:
           name: proton-drive-linux-builds
 
+      # The release notes are this version's section of the changelog, from its
+      # heading up to the next one.
+      - name: Extract release notes
+        run: |
+          version="${GITHUB_REF_NAME#v}"
+          awk -v heading="## [$version]" \
+            'index($0, heading) == 1 { found = 1; print; next }
+             found && /^## \[/ { exit }
+             found' docs/CHANGELOG.md > release-notes.md
+          if [ ! -s release-notes.md ]; then
+            echo "::error::docs/CHANGELOG.md has no section for $version"
+            exit 1
+          fi
+
       - name: Create GitHub Release
         uses: softprops/action-gh-release@v3
         with:
+          body_path: release-notes.md
           files: |
             *.deb
             *.tar.gz
+            *.tar.xz
             *.rpm
           draft: false
           prerelease: false
@@ -263,3 +322,21 @@ jobs:
       version: ${{ github.ref_name }}
     secrets:
       AUR_SSH_PRIVATE_KEY: ${{ secrets.AUR_SSH_PRIVATE_KEY }}
+
+  copr:
+    name: Build COPR packages
+    needs: publish
+    if: startsWith(github.ref, 'refs/tags/')
+    uses: ./.github/workflows/copr.yml
+    with:
+      version: ${{ github.ref_name }}
+    secrets:
+      COPR_CONFIG: ${{ secrets.COPR_CONFIG }}
+
+  wiki:
+    name: Publish the wiki
+    needs: publish
+    if: startsWith(github.ref, 'refs/tags/')
+    uses: ./.github/workflows/wiki.yml
+    with:
+      ref: ${{ github.ref_name }}

.github/workflows/test-build.yml

@@ -0,0 +1,121 @@
+name: Test build
+
+# On-demand Fedora RPM of any branch, for someone to try a fix before it ships.
+# Run it from the Actions tab ("Run workflow", pick the branch). Built inside a
+# Fedora container so the binaries link against Fedora's own GTK, libadwaita and
+# WebKitGTK, not the Ubuntu ones the release RPM is built against.
+#
+# The RPM is unsigned and versioned `<Cargo version>-1.test.<sha>`, so it sorts
+# below the release it precedes and `dnf` replaces it when that ships.
+on:
+  workflow_dispatch:
+    inputs:
+      fedora:
+        description: 'Fedora release to build on'
+        required: false
+        default: '44'
+        type: string
+      prerelease:
+        description: 'Also publish a pre-release anyone can download without a GitHub login'
+        required: false
+        default: false
+        type: boolean
+
+permissions:
+  contents: read
+
+concurrency:
+  group: test-build-${{ github.ref }}
+  cancel-in-progress: true
+
+jobs:
+  rpm:
+    name: Fedora ${{ inputs.fedora }} RPM
+    runs-on: ubuntu-24.04
+    container: fedora:${{ inputs.fedora }}
+    steps:
+      - name: Install build dependencies
+        run: |
+          dnf install -y --setopt=install_weak_deps=False \
+            git rpm-build gcc gcc-c++ make gettext curl \
+            pkgconf-pkg-config fuse3-devel gtk4-devel libadwaita-devel \
+            libsecret-devel dbus-devel glib2-devel webkitgtk6.0-devel
+
+      - name: Checkout repository
+        uses: actions/checkout@v7
+
+      # Fedora's packaged Rust can trail the workspace's minimum (1.96).
+      - name: Set up Rust
+        uses: actions-rust-lang/setup-rust-toolchain@v1
+        with:
+          toolchain: '1.96'
+          cache: false
+
+      - name: Cache Cargo target
+        uses: swatinem/rust-cache@v2
+        with:
+          shared-key: fedora-test-build
+          save-if: false
+
+      - name: Build release binaries
+        run: cargo build --release --locked
+
+      - name: Package RPM
+        run: |
+          git config --global --add safe.directory "$GITHUB_WORKSPACE"
+          VERSION=$(grep -m1 '^version' Cargo.toml | cut -d'"' -f2)
+          SHORT=${GITHUB_SHA::7}
+          mkdir -p rpmbuild/{BUILD,RPMS,SOURCES,SPECS,SRPMS,BUILDROOT,db}
+          rpmbuild -bb \
+            --nodeps \
+            --define "_topdir $PWD/rpmbuild" \
+            --define "_sourcedir $PWD" \
+            --define "git_dir $PWD" \
+            --define "prebuilt 1" \
+            --define "version ${VERSION}" \
+            --define "dist .test.${SHORT}" \
+            --define "_dbpath $PWD/rpmbuild/db" \
+            packaging/proton-drive-linux.spec
+          mkdir -p out
+          cp rpmbuild/RPMS/x86_64/*.rpm out/
+          # The bare binaries, for trying one without installing anything.
+          tar -czf "out/proton-drive-linux-${VERSION}-${SHORT}-fedora${{ inputs.fedora }}-x86_64.tar.gz" \
+            -C target/release pdfs pdfs-tray pdfs-app pdfs-prompt
+          ls -l out
+
+      - name: Upload artifact
+        uses: actions/upload-artifact@v7
+        with:
+          name: proton-drive-linux-fedora${{ inputs.fedora }}-${{ github.sha }}
+          path: out/*
+          retention-days: 14
+          if-no-files-found: error
+
+  prerelease:
+    name: Publish pre-release
+    needs: rpm
+    if: inputs.prerelease
+    runs-on: ubuntu-24.04
+    permissions:
+      contents: write
+    steps:
+      - name: Download build
+        uses: actions/download-artifact@v8
+        with:
+          path: out
+          merge-multiple: true
+
+      # One rolling pre-release per branch: a new run replaces the last one, so
+      # the link a tester was given keeps pointing at the newest build.
+      - name: Publish
+        env:
+          GH_TOKEN: ${{ github.token }}
+          GH_REPO: ${{ github.repository }}
+        run: |
+          TAG="test-$(echo "${GITHUB_REF_NAME}" | tr -c 'A-Za-z0-9._\n' '-')"
+          gh release delete "$TAG" --cleanup-tag --yes 2>/dev/null || true
+          gh release create "$TAG" out/* \
+            --target "$GITHUB_SHA" \
+            --prerelease \
+            --title "Test build of ${GITHUB_REF_NAME} (${GITHUB_SHA::7})" \
+            --notes "Unsigned test build of branch \`${GITHUB_REF_NAME}\` at ${GITHUB_SHA}. Not a release; replaced by the next test build of this branch."

.github/workflows/wiki.yml

@@ -0,0 +1,77 @@
+name: Wiki
+
+# docs/ is the source of the GitHub wiki (docs/DEVELOPMENT.md#common-changes).
+# Every change to the documentation checks its links; release.yml calls this
+# once the release is published, so the wiki documents the latest release. Run
+# it from the Actions tab to publish main in between.
+on:
+  push:
+    branches: [main]
+    paths:
+      - 'docs/**'
+      - 'images/**'
+      - 'README.md'
+      - 'CONTRIBUTING.md'
+      - 'SECURITY.md'
+      - 'scripts/publish-wiki.sh'
+      - '.github/workflows/wiki.yml'
+  pull_request:
+    paths:
+      - 'docs/**'
+      - 'images/**'
+      - 'README.md'
+      - 'CONTRIBUTING.md'
+      - 'SECURITY.md'
+      - 'scripts/publish-wiki.sh'
+      - '.github/workflows/wiki.yml'
+  workflow_call:
+    inputs:
+      ref:
+        description: 'Tag or branch to publish'
+        required: true
+        type: string
+  workflow_dispatch:
+    inputs:
+      ref:
+        description: 'Tag or branch to publish'
+        required: false
+        default: 'main'
+        type: string
+
+permissions:
+  contents: read
+
+jobs:
+  check:
+    name: Check documentation links
+    if: inputs.ref == ''
+    runs-on: ubuntu-24.04
+    steps:
+      - uses: actions/checkout@v7
+
+      - name: Check links
+        run: scripts/publish-wiki.sh --check "$RUNNER_TEMP"
+
+  publish:
+    name: Publish to the wiki
+    # Set only by release.yml and the Actions tab, so pushes and pull requests
+    # never publish.
+    if: inputs.ref != ''
+    runs-on: ubuntu-24.04
+    concurrency:
+      group: wiki-publish
+      cancel-in-progress: false
+    permissions:
+      contents: write
+    steps:
+      - uses: actions/checkout@v7
+        with:
+          ref: ${{ inputs.ref }}
+
+      - name: Publish
+        env:
+          WIKI_REMOTE: https://x-access-token:${{ github.token }}@github.com/${{ github.repository }}.wiki.git
+        run: |
+          git config --global user.name 'github-actions[bot]'
+          git config --global user.email '41898282+github-actions[bot]@users.noreply.github.com'
+          scripts/publish-wiki.sh --push "$RUNNER_TEMP"

.gitignore

@@ -3,3 +3,5 @@
 *.pdb
 .env
 /rpmbuild
+/result
+/result-*

CONTRIBUTING.md

@@ -6,10 +6,10 @@ deliberately high — everything else is ordinary Rust review.
 
 ## Before you start
 
-- Read [`AGENTS.md`](AGENTS.md) for repository conventions,
-  [`docs/DEVELOPMENT.md`](docs/DEVELOPMENT.md) for building, running and debugging from source,
-  and [`docs/ARCHITECTURE.md`](docs/ARCHITECTURE.md) for how the daemon, front ends, and SDK fit
-  together. [`docs/README.md`](docs/README.md) indexes the rest.
+- Read [`docs/DEVELOPMENT.md`](docs/DEVELOPMENT.md) for building, running and debugging from
+  source, and [`docs/ARCHITECTURE.md`](docs/ARCHITECTURE.md) for how the daemon, front ends, and
+  SDK fit together. [`docs/README.md`](docs/README.md) indexes the rest. The same pages are on
+  the [wiki](https://github.com/narrrl/proton-drive-linux/wiki).
 - Check [`docs/BUGS.md`](docs/BUGS.md) — it is the authoritative issue ledger, and your problem may
   already be tracked there with context.
 - For anything larger than a fix, open an issue first so the design can be discussed before you
@@ -58,8 +58,10 @@ runs are destructive: use a dedicated test account, never one holding data you c
   catalog in `po/LINGUAS` in the same change. See [`docs/TRANSLATING.md`](docs/TRANSLATING.md).
   The CLI and daemon messages stay in English.
 - **Document what users see.** A new command, setting or behaviour belongs in the matching page
-  under `docs/` (user guide, CLI reference or configuration) and in the `[Unreleased]` section of
-  [`docs/CHANGELOG.md`](docs/CHANGELOG.md).
+  under `docs/` (a user guide topic, the CLI reference or configuration) and in the `[Unreleased]`
+  section of [`docs/CHANGELOG.md`](docs/CHANGELOG.md). Each release publishes `docs/` to the
+  wiki. A new page goes into `SECTIONS` in `scripts/publish-wiki.sh`, and
+  `scripts/publish-wiki.sh --check` must pass. CI runs it on every change to `docs/`.
 
 ## Commits and pull requests
 

Cargo.toml

@@ -3,7 +3,7 @@ resolver = "2"
 members = ["crates/pdfs-core", "crates/pdfs-fuse", "crates/pdfs-cli", "crates/pdfs-gui"]
 
 [workspace.package]
-version = "3.0.0"
+version = "3.7.0"
 edition = "2024"
 license = "MIT"
 authors = ["Nils Pukropp <contact@narl.io>"]
@@ -15,8 +15,8 @@ keywords = ["proton", "drive", "fuse", "sync", "linux"]
 categories = ["filesystem", "command-line-utilities"]
 
 [workspace.dependencies]
-proton-sdk = { version = "0.7.2" }
-proton-drive-rs = { version = "0.7.2" }
+proton-sdk = { version = "0.10.1" }
+proton-drive-rs = { version = "0.10.1" }
 
 # Internal crates.
 pdfs-core = { path = "crates/pdfs-core" }
@@ -26,13 +26,14 @@ tokio = { version = "1", features = ["rt-multi-thread", "macros", "sync", "fs",
 serde = { version = "1", features = ["derive"] }
 serde_json = "1"
 base64 = "0.23"
+zeroize = "1"
 thiserror = "2"
 anyhow = "1"
 # Non-poisoning mutexes. A handler that panics while holding a lock must not
 # wedge every later acquisition of it: `Workers` catches the unwind to keep the
 # pool alive, and `std::sync::Mutex` would defeat that by poisoning the state
 # the recovered worker needs.
-parking_lot = "0.12"
+parking_lot = "0.13"
 tracing = "0.1"
 tracing-subscriber = { version = "0.3", features = ["env-filter"] }
 directories = "6"
@@ -40,7 +41,7 @@ ignore = "0.4"
 sha2 = "0.11"
 # Google Takeout exports are zip sets; the importer reads their central
 # directories and streams entries out without extracting to disk first.
-zip = { version = "8", default-features = false, features = ["deflate"] }
+zip = { version = "9", default-features = false, features = ["deflate"] }
 # Proton's photo duplicate detection is keyed on the plaintext SHA-1, so an
 # import has to speak SHA-1 whatever its age.
 sha1 = "0.11"
@@ -48,7 +49,7 @@ sha1 = "0.11"
 # formats a camera or phone actually produces — the rest of the crate's codecs
 # would be dead weight in the daemon.
 image = { version = "0.25", default-features = false, features = ["jpeg", "png", "webp", "gif", "tiff", "bmp", "rayon"] }
-rusqlite = { version = "0.40", features = ["bundled"] }
+rusqlite = { version = "0.41", features = ["bundled"] }
 # keyring 4 split into `keyring-core` plus per-platform stores. The libdbus
 # Secret Service store is the one keyring 3's `sync-secret-service` wrapped, and
 # with no `target` it matches items v3 wrote, so existing logins survive.
@@ -60,3 +61,15 @@ async-trait = "0.1"
 futures = "0.3"
 fuser = "0.18"
 libc = "0.2"
+
+[profile.release]
+# No package ships a separate debug package (the PKGBUILD sets `!debug`, the
+# RPM spec sets `debug_package` to nil), and the unstripped binaries weighed
+# 43 MB (`pdfs`), 24 MB (`pdfs-app`) and 12 MB (`pdfs-tray`).
+strip = "symbols"
+# Off on purpose: LTO has broken GTK links for this workspace, which is why
+# the packages turn it off as well.
+lto = false
+# `Workers` and the thumbnail build catch panics to keep the daemon alive, so
+# unwinding must stay on.
+panic = "unwind"

README.md

@@ -73,15 +73,30 @@ scriptable CLI.
 
 | Distribution | Package |
 |---|---|
-| Debian, Ubuntu 24.04 or newer | `.deb` from the [latest release](https://github.com/narrrl/proton-drive-linux/releases/latest) |
-| Fedora 44 or newer | `.rpm` from the [latest release](https://github.com/narrrl/proton-drive-linux/releases/latest) |
+| Fedora 44 or newer | [`narl-rs/proton-drive-linux`](https://copr.fedorainfracloud.org/coprs/narl-rs/proton-drive-linux/) in COPR, updated with `dnf upgrade` |
 | Arch Linux | [`proton-drive-for-linux`](https://aur.archlinux.org/packages/proton-drive-for-linux) (also `-bin` and `-git`) in the AUR |
+| Debian, Ubuntu 24.04 or newer | `.deb` from the [latest release](https://github.com/narrrl/proton-drive-linux/releases/latest) |
+| NixOS | The flake in this repository: see [Installation → NixOS](docs/INSTALL.md#nixos-flake) |
 | Anything else | [Build from source](docs/INSTALL.md#build-from-source) |
 
+**Fedora**
+
 ```bash
-sudo apt install ./proton-drive-linux_*.deb        # Debian, Ubuntu
-sudo dnf install ./proton-drive-linux-*.rpm        # Fedora
-paru -S proton-drive-for-linux                     # Arch
+sudo dnf copr enable narl-rs/proton-drive-linux
+sudo dnf install proton-drive-linux
+```
+
+**Arch Linux**
+
+```bash
+paru -S proton-drive-for-linux
+```
+
+**Debian and Ubuntu:** download the `.deb` from the
+[latest release](https://github.com/narrrl/proton-drive-linux/releases/latest), then:
+
+```bash
+sudo apt install ./proton-drive-linux_*_amd64.deb
 ```
 
 Then open **Proton Drive** from your applications menu and sign in. The app starts the background
@@ -96,18 +111,25 @@ systemctl --user enable --now proton-drive.service
 pdfs status
 ```
 
-[docs/INSTALL.md](docs/INSTALL.md) has the requirements, optional extras (tray on GNOME, RAW and
-video thumbnails), headless use and uninstalling.
+New to the client? [Getting started](docs/GETTING_STARTED.md) walks through the first steps.
+[Installation](docs/INSTALL.md) has the optional extras (tray on GNOME, RAW and video
+thumbnails), updating, headless use and uninstalling.
 
 ## Documentation
 
+The documentation is in [`docs/`](docs/README.md) and on the
+[wiki](https://github.com/narrrl/proton-drive-linux/wiki).
+
 | | |
 |---|---|
+| [Getting started](docs/GETTING_STARTED.md) | From installing to your first synced folder |
 | [User guide](docs/USER_GUIDE.md) | Everything the app, tray and launcher do |
+| [FAQ](docs/FAQ.md) | Short answers to common questions |
 | [Command-line reference](docs/CLI.md) | Every `pdfs` command and scripting with `--json` |
 | [Configuration](docs/CONFIGURATION.md) | `config.json`, file locations, environment variables, the service |
 | [Troubleshooting](docs/TROUBLESHOOTING.md) | Diagnosing problems and fixing common ones |
 | [Recovering on a new computer](docs/RECOVERY.md) | Getting your synced folders back after a reinstall or a lost machine |
+| [Security model](docs/SECURITY_MODEL.md) | What protects your files, what stays on this computer, what the client connects to |
 | [Changelog](docs/CHANGELOG.md) | What changed in each release |
 
 For contributors: [development guide](docs/DEVELOPMENT.md), [architecture](docs/ARCHITECTURE.md),
@@ -149,7 +171,8 @@ keys before it leaves the machine, through a Rust implementation of Proton's Dri
 
 Files you open are decrypted into a local cache so programs can read them. What that means for
 the security of the machine is spelled out in the
-[threat model](docs/ARCHITECTURE.md#10-threat-model-what-this-client-writes-to-disk-in-plaintext).
+[security model](docs/SECURITY_MODEL.md#what-is-kept-on-this-computer), and in full detail in
+the [threat model](docs/ARCHITECTURE.md#10-threat-model-what-this-client-writes-to-disk-in-plaintext).
 
 ## Contributing
 

SECURITY.md

@@ -4,6 +4,9 @@
 
 Fixes land on the latest release. Please reproduce on the most recent version before reporting.
 
+For what the client protects and what it does not, written for users, see the
+[security model](docs/SECURITY_MODEL.md).
+
 ## Reporting a vulnerability
 
 **Do not open a public issue.** Report privately through GitHub's

crates/pdfs-cli/Cargo.toml

@@ -23,3 +23,4 @@ tracing-subscriber.workspace = true
 clap.workspace = true
 rpassword.workspace = true
 serde_json.workspace = true
+zeroize.workspace = true

crates/pdfs-cli/src/journal.rs

@@ -0,0 +1,122 @@
+//! Log priorities for journald.
+//!
+//! journald files each line a service writes at the unit's default priority,
+//! info, unless the line opens with a syslog `<N>` prefix. Without one every
+//! WARN and ERROR the daemon logs is stored as info, and the
+//! `journalctl -p warning` that the troubleshooting guide asks for shows
+//! nothing (`docs/BUGS.md` B258).
+
+use std::fmt;
+use std::os::unix::fs::MetadataExt;
+
+use tracing::{Event, Level, Subscriber};
+use tracing_subscriber::fmt::format::Writer;
+use tracing_subscriber::fmt::{FmtContext, FormatEvent, FormatFields};
+use tracing_subscriber::registry::LookupSpan;
+
+/// Whether standard output is the journal stream systemd connected this
+/// process to.
+///
+/// `JOURNAL_STREAM` alone does not say so: a terminal started from a user unit
+/// inherits it, and every `pdfs` run in that terminal would print the
+/// prefixes. systemd sets it to the stream's `device:inode`, so it is compared
+/// against what fd 1 actually is.
+pub(crate) fn stdout_is_journal() -> bool {
+    let Some(stream) = std::env::var_os("JOURNAL_STREAM") else {
+        return false;
+    };
+    let Ok(stdout) = std::fs::metadata("/proc/self/fd/1") else {
+        return false;
+    };
+    stream
+        .to_str()
+        .is_some_and(|value| names_stream(value, stdout.dev(), stdout.ino()))
+}
+
+/// Whether a `JOURNAL_STREAM` value names the file `dev`:`ino`.
+fn names_stream(value: &str, dev: u64, ino: u64) -> bool {
+    value
+        .split_once(':')
+        .is_some_and(|(d, i)| d.parse() == Ok(dev) && i.parse() == Ok(ino))
+}
+
+/// The syslog priority journald should file a `level` line at.
+fn priority(level: &Level) -> u8 {
+    match *level {
+        Level::ERROR => 3,
+        Level::WARN => 4,
+        Level::INFO => 6,
+        Level::DEBUG | Level::TRACE => 7,
+    }
+}
+
+/// An event format that opens each line with its `<N>` priority, then writes
+/// the line as `F` would.
+pub(crate) struct Prioritized<F>(pub(crate) F);
+
+impl<S, N, F> FormatEvent<S, N> for Prioritized<F>
+where
+    S: Subscriber + for<'a> LookupSpan<'a>,
+    N: for<'a> FormatFields<'a> + 'static,
+    F: FormatEvent<S, N>,
+{
+    fn format_event(
+        &self,
+        ctx: &FmtContext<'_, S, N>,
+        mut writer: Writer<'_>,
+        event: &Event<'_>,
+    ) -> fmt::Result {
+        write!(writer, "<{}>", priority(event.metadata().level()))?;
+        self.0.format_event(ctx, writer, event)
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use std::io;
+    use std::sync::{Arc, Mutex};
+
+    #[derive(Clone)]
+    struct Buf(Arc<Mutex<Vec<u8>>>);
+
+    impl io::Write for Buf {
+        fn write(&mut self, bytes: &[u8]) -> io::Result<usize> {
+            self.0.lock().unwrap().extend_from_slice(bytes);
+            Ok(bytes.len())
+        }
+        fn flush(&mut self) -> io::Result<()> {
+            Ok(())
+        }
+    }
+
+    #[test]
+    fn each_line_opens_with_the_priority_of_its_level() {
+        let buf = Buf(Arc::new(Mutex::new(Vec::new())));
+        let writer = buf.clone();
+        let subscriber = tracing_subscriber::fmt()
+            .with_max_level(Level::DEBUG)
+            .with_ansi(false)
+            .with_writer(move || writer.clone())
+            .event_format(Prioritized(tracing_subscriber::fmt::format()))
+            .finish();
+        tracing::subscriber::with_default(subscriber, || {
+            tracing::error!("e");
+            tracing::warn!("w");
+            tracing::info!("i");
+            tracing::debug!("d");
+        });
+        let out = String::from_utf8(buf.0.lock().unwrap().clone()).unwrap();
+        let prefixes: Vec<&str> = out.lines().map(|line| &line[..3]).collect();
+        assert_eq!(prefixes, ["<3>", "<4>", "<6>", "<7>"]);
+    }
+
+    #[test]
+    fn journal_stream_must_name_the_same_file() {
+        assert!(names_stream("8:12345", 8, 12345));
+        assert!(!names_stream("8:12345", 8, 54321));
+        assert!(!names_stream("9:12345", 8, 12345));
+        assert!(!names_stream("8", 8, 12345));
+        assert!(!names_stream("", 8, 12345));
+    }
+}

crates/pdfs-core/Cargo.toml

@@ -28,3 +28,6 @@ dbus-secret-service-keyring-store.workspace = true
 parking_lot.workspace = true
 async-trait.workspace = true
 libc.workspace = true
+zeroize.workspace = true
+base64.workspace = true
+exif = { version = "0.6", package = "kamadak-exif" }

crates/pdfs-core/src/cache.rs

@@ -621,10 +621,20 @@ impl ContentCache {
             for entry in rd.flatten() {
                 let name = entry.file_name();
                 let Some(name) = name.to_str() else { continue };
+                // A `.meta` tags the blob named like it without the suffix. One
+                // whose blob is gone is what an eviction leaves between its two
+                // removals, by a crash or by a store of the same uid landing in
+                // between, and nothing else would ever remove it.
+                if let Some(blob) = name.strip_suffix(".meta") {
+                    if !dir.join(blob).exists() {
+                        let _ = std::fs::remove_file(entry.path());
+                    }
+                    continue;
+                }
                 // `.geom` is a block-geometry sidecar (see `GeometryMeta`), tens
                 // of bytes and not a cached block; like `.meta` it is neither
                 // budgeted nor evictable on its own.
-                if name.ends_with(".meta") || name.ends_with(".geom") {
+                if name.ends_with(".geom") {
                     continue;
                 }
                 // A `.tmp` is a staging file from a store that never completed
@@ -2250,6 +2260,28 @@ mod tests {
         assert!(total <= 8, "budget enforced after reconcile, total={total}");
     }
 
+    /// An eviction removes the blob, then its tag. A crash in between, or a
+    /// store of the same uid landing in between, left the tag on its own, and
+    /// nothing removed it.
+    #[test]
+    fn a_tag_without_its_blob_is_swept_at_open() {
+        let dir = TempDir::new();
+        let content = dir.path().join("content");
+        let pins = dir.path().join("pins.json");
+        let db = Arc::new(Db::open_in_memory().unwrap());
+        {
+            let c = ContentCache::open(content.clone(), pins.clone(), 0, db.clone()).unwrap();
+            c.store(&uid("kept"), 1, 4, b"kept").unwrap();
+            c.store(&uid("gone"), 1, 4, b"gone").unwrap();
+            std::fs::remove_file(c.blob_path(&uid("gone"))).unwrap();
+        }
+
+        let c = ContentCache::open(content, pins, 0, db).unwrap();
+        assert!(!c.meta_path(&uid("gone")).exists());
+        assert!(c.meta_path(&uid("kept")).exists());
+        assert_eq!(c.read_range(&uid("kept"), 1, 4, 0, 4).unwrap(), b"kept");
+    }
+
     #[test]
     fn stale_metadata_is_a_miss() {
         let (c, _d) = cache();
@@ -2309,42 +2341,26 @@ mod tests {
     /// call also needs.
     #[test]
     fn budget_check_is_free_when_under_budget() {
-        use std::time::Instant;
-
         // Cap far above what we store, so every store stays under budget.
         let (c, _d) = cache_capped(1 << 30);
         let payload = vec![0u8; 4096];
-
-        // Cost of a store against a near-empty index...
-        let t = Instant::now();
-        for i in 0..500u64 {
+        for i in 0..8u64 {
             c.store_block(&uid("a"), 1, 1 << 30, blk(1 << 30, i), &payload)
                 .unwrap();
         }
-        let empty = t.elapsed() / 500;
 
-        // ...and against one with a few thousand entries in it.
-        for i in 500..2500u64 {
-            c.store_block(&uid("a"), 1, 1 << 30, blk(1 << 30, i), &payload)
-                .unwrap();
-        }
-        let t = Instant::now();
-        for i in 2500..3000u64 {
-            c.store_block(&uid("a"), 1, 1 << 30, blk(1 << 30, i), &payload)
-                .unwrap();
-        }
-        let full = t.elapsed() / 500;
+        // Plant an index row far over the cap behind the running total's back,
+        // and older than every real block. Any budget check that consults the
+        // index would see the pool over budget, evict, and reseed the total.
+        c.db.cache_touch("planted", KIND_BLOCK, 1 << 40, 0).unwrap();
 
-        println!("B4: store_block under budget — {empty:?} at ~0 entries, {full:?} at 2500");
-        // A ratio, not a wall-clock bound: the claim is that the under-budget
-        // path does not grow with the index, and only a ratio tests that. An
-        // absolute threshold measures the machine's load instead, and this test
-        // runs alongside the rest of the suite.
-        assert!(
-            full < empty * 3,
-            "under-budget store should not scale with the index: \
-             {empty:?} at ~0 entries vs {full:?} at 2500"
-        );
+        c.store_block(&uid("a"), 1, 1 << 30, blk(1 << 30, 8), &payload)
+            .unwrap();
+
+        // Not a timing ratio: that measured the CI runner's load and flaked.
+        assert_eq!(c.block_bytes.load(Ordering::Relaxed), 9 * 4096);
+        let entries = c.db.cache_entries_by_kind(KIND_BLOCK).unwrap();
+        assert_eq!(entries.len(), 10, "under-budget store evicted: {entries:?}");
     }
 
     /// The running totals are a fast path, not a second source of truth: after

crates/pdfs-core/src/config.rs

@@ -3,7 +3,7 @@
 use std::path::{Path, PathBuf};
 
 use directories::ProjectDirs;
-use serde::{Deserialize, Serialize};
+use serde::{Deserialize, Deserializer, Serialize};
 
 use crate::error::{Error, Result};
 use crate::menu::PromptConfig;
@@ -12,8 +12,19 @@ use crate::syncignore::DEFAULT_IGNORE_PATTERNS;
 
 /// Proton requires `external-drive-{name}@{semver}-{channel}` (channel ∈
 /// stable/beta/alpha); a malformed value trips the 422 anti-abuse path.
-pub const APP_VERSION: &str = "external-drive-linux@0.1.0-alpha";
-pub const USER_AGENT: &str = "proton-drive-linux/0.1.0";
+/// Follows the release so Proton can tell releases apart and retire old ones
+/// without retiring every one.
+pub const APP_VERSION: &str = concat!(
+    "external-drive-linux@",
+    env!("CARGO_PKG_VERSION"),
+    "-stable"
+);
+pub const USER_AGENT: &str = concat!("proton-drive-linux/", env!("CARGO_PKG_VERSION"));
+
+/// The fixed identity every release up to 3.1.0 wrote into `config.json`. Read
+/// back as "unset" so those configs follow the release instead of pinning it.
+const LEGACY_APP_VERSION: &str = "external-drive-linux@0.1.0-alpha";
+const LEGACY_USER_AGENT: &str = "proton-drive-linux/0.1.0";
 
 /// Keyring service name; one entry per credential kind keyed by username.
 pub const KEYRING_SERVICE: &str = "proton-drive-linux";
@@ -76,10 +87,24 @@ fn resolve_sweep_mode(env: Option<&str>, stored: Option<SweepMode>) -> SweepMode
 }
 
 /// Configuration structure allowing the user to customize client identification headers.
-#[derive(Serialize, Deserialize, Debug, Clone)]
+#[derive(Serialize, Deserialize, Debug, Clone, Default)]
 pub struct AppConfig {
-    pub app_version: String,
-    pub user_agent: String,
+    /// Override for [`APP_VERSION`]. `None` means "use the release's own";
+    /// the old fixed default reads as `None`, so it leaves the file on the
+    /// next save.
+    #[serde(
+        default,
+        deserialize_with = "identity_override",
+        skip_serializing_if = "Option::is_none"
+    )]
+    pub app_version: Option<String>,
+    /// Override for [`USER_AGENT`], handled like `app_version`.
+    #[serde(
+        default,
+        deserialize_with = "identity_override",
+        skip_serializing_if = "Option::is_none"
+    )]
+    pub user_agent: Option<String>,
     /// Soft cap on the on-disk content cache, in bytes (`0` = unlimited).
     /// `None` means "use [`DEFAULT_CACHE_BUDGET_BYTES`]"; the Settings page
     /// writes an explicit value here. Defaulted for configs predating the field.
@@ -138,6 +163,10 @@ pub struct AppConfig {
     /// Defaulted for configs predating the field.
     #[serde(default)]
     pub files_view: FilesView,
+    /// The desktop app's main window size, remembered between runs. Defaulted
+    /// for configs predating the field.
+    #[serde(default)]
+    pub window: WindowState,
     /// The user hid the tray icon from its own menu. The tray exits at start
     /// while this is set, and the app does not spawn it; Preferences turns it
     /// back on. Defaulted for configs predating the field.
@@ -161,6 +190,24 @@ pub struct AppConfig {
     /// the field.
     #[serde(default)]
     pub local_first: Option<bool>,
+    /// Ask GitHub once a day whether a newer release is out, and say so in the
+    /// desktop app. Off by default: GitHub then sees the address and version
+    /// asking. Never used where a package manager installs updates (see
+    /// [`crate::update::updates_managed`]). Defaulted for configs predating the
+    /// field.
+    #[serde(default)]
+    pub update_check: bool,
+    /// When the update check last asked GitHub, in Unix seconds, so a restart
+    /// does not ask again within [`crate::update::CHECK_INTERVAL`]. Defaulted
+    /// for configs predating the field.
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    pub update_last_checked: Option<i64>,
+    /// The latest release that check found, such as `3.6.0`, so the app can
+    /// say so again after a restart without asking. Older than or equal to the
+    /// running version once the update is installed. Defaulted for configs
+    /// predating the field.
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    pub update_latest: Option<String>,
 }
 
 /// The My Files page's view choices, remembered between runs.
@@ -186,6 +233,44 @@ impl Default for FilesView {
     }
 }
 
+/// The desktop app's main window, as it was when it last closed.
+#[derive(Serialize, Deserialize, Debug, Clone, Copy, PartialEq, Eq)]
+#[serde(default)]
+pub struct WindowState {
+    /// The unmaximised size, in logical pixels.
+    pub width: i32,
+    pub height: i32,
+    pub maximized: bool,
+}
+
+impl WindowState {
+    /// Below this the saved size is taken for damage and the default is used.
+    pub const MIN_WIDTH: i32 = 480;
+    pub const MIN_HEIGHT: i32 = 400;
+
+    /// This state, with a size too small to use replaced by the default.
+    pub fn usable(self) -> Self {
+        if self.width < Self::MIN_WIDTH || self.height < Self::MIN_HEIGHT {
+            Self {
+                maximized: self.maximized,
+                ..Self::default()
+            }
+        } else {
+            self
+        }
+    }
+}
+
+impl Default for WindowState {
+    fn default() -> Self {
+        Self {
+            width: 980,
+            height: 680,
+            maximized: false,
+        }
+    }
+}
+
 /// The key a My Files listing is ordered by.
 #[derive(Serialize, Deserialize, Debug, Clone, Copy, PartialEq, Eq, Default)]
 #[serde(rename_all = "lowercase")]
@@ -216,31 +301,28 @@ impl FileSort {
     }
 }
 
-impl Default for AppConfig {
-    fn default() -> Self {
-        Self {
-            app_version: APP_VERSION.to_string(),
-            user_agent: USER_AGENT.to_string(),
-            cache_budget: None,
-            upload_limit: None,
-            download_limit: None,
-            mountpoint: None,
-            ignore_patterns: None,
-            device_uid: None,
-            conflict_sweep: None,
-            open_with: None,
-            prompt: None,
-            proton_theme: None,
-            files_view: FilesView::default(),
-            tray_hidden: false,
-            language: None,
-            online_map: false,
-            local_first: None,
-        }
-    }
+/// Reads an `app_version` or `user_agent` override, dropping the fixed
+/// identity older releases stored as the default.
+fn identity_override<'de, D: Deserializer<'de>>(
+    deserializer: D,
+) -> std::result::Result<Option<String>, D::Error> {
+    let value = Option::<String>::deserialize(deserializer)?;
+    Ok(value.filter(|v| v != LEGACY_APP_VERSION && v != LEGACY_USER_AGENT))
 }
 
 impl AppConfig {
+    /// The `x-pm-appversion` sent to Proton: the user's override, or
+    /// [`APP_VERSION`].
+    pub fn resolved_app_version(&self) -> &str {
+        self.app_version.as_deref().unwrap_or(APP_VERSION)
+    }
+
+    /// The `User-Agent` sent to Proton: the user's override, or
+    /// [`USER_AGENT`].
+    pub fn resolved_user_agent(&self) -> &str {
+        self.user_agent.as_deref().unwrap_or(USER_AGENT)
+    }
+
     /// The effective cache budget in bytes: the user's explicit choice, or
     /// [`DEFAULT_CACHE_BUDGET_BYTES`] when unset.
     pub fn resolved_cache_budget(&self) -> u64 {
@@ -288,6 +370,22 @@ impl AppConfig {
     }
 }
 
+/// Fail when the config file at `path` exists but does not parse, so that
+/// [`AppDirs::save_config`] never writes over settings it could not read.
+fn refuse_to_replace_unreadable(path: &Path) -> Result<()> {
+    match std::fs::read_to_string(path) {
+        Ok(content) => match serde_json::from_str::<AppConfig>(&content) {
+            Ok(_) => Ok(()),
+            Err(e) => Err(Error::Other(format!(
+                "{} cannot be read ({e}); fix it or move it aside before changing settings",
+                path.display()
+            ))),
+        },
+        Err(e) if e.kind() == std::io::ErrorKind::NotFound => Ok(()),
+        Err(e) => Err(e.into()),
+    }
+}
+
 /// Resolved XDG locations for state, cache, and the default mountpoint.
 pub struct AppDirs {
     dirs: ProjectDirs,
@@ -319,6 +417,7 @@ impl AppDirs {
                     // Preserve the original bytes for diagnosis/recovery.  In
                     // particular, never replace a truncated config with defaults
                     // and silently lose mount, device, or ignore settings.
+                    // `save_config` refuses to write over it for the same reason.
                     tracing::error!(path = %path.display(), error = %e, "config is unreadable; using in-memory defaults without overwriting it");
                     return AppConfig::default();
                 }
@@ -326,9 +425,8 @@ impl AppDirs {
         }
 
         let default_config = AppConfig::default();
-        if let Ok(content) = serde_json::to_string_pretty(&default_config) {
-            let _ = std::fs::create_dir_all(self.dirs.config_dir());
-            let _ = std::fs::write(&path, content);
+        if let Err(e) = self.save_config(&default_config) {
+            tracing::warn!(path = %path.display(), error = %e, "could not write the default config");
         }
         default_config
     }
@@ -336,8 +434,15 @@ impl AppDirs {
     /// Persist `config` to [`config_path`](Self::config_path), creating the
     /// config dir if missing. The Settings page calls this after editing the
     /// cache budget or mountpoint; the daemon re-reads the file on its next mount.
+    ///
+    /// Refuses while the file on disk does not parse. Every caller loads,
+    /// changes one field and saves, and [`load_config`](Self::load_config)
+    /// gives defaults for a file it cannot read, so the first change after
+    /// the file was damaged wrote defaults over the mountpoint, the device and
+    /// the ignore rules the user had (`docs/BUGS.md` B223).
     pub fn save_config(&self, config: &AppConfig) -> Result<()> {
         let path = self.config_path();
+        refuse_to_replace_unreadable(&path)?;
         let parent = path
             .parent()
             .ok_or_else(|| Error::Other("configuration path has no parent".into()))?;
@@ -361,6 +466,46 @@ impl AppDirs {
         Ok(())
     }
 
+    /// This machine's id (e.g. ~/.config/proton-drive-linux/machine-id). See
+    /// [`machine_id`](Self::machine_id).
+    pub fn machine_id_path(&self) -> PathBuf {
+        self.dirs.config_dir().join("machine-id")
+    }
+
+    /// A random id for this machine, made on first use and kept in
+    /// [`machine_id_path`](Self::machine_id_path).
+    ///
+    /// It names this machine's profile in a device it may share with other
+    /// computers. Random rather than `/etc/machine-id`, so nothing that
+    /// identifies the host goes to Drive. In a file of its own rather than
+    /// `config.json`, because the app saves the config from a copy it loaded
+    /// earlier, and that would drop an id the daemon had just added.
+    pub fn machine_id(&self) -> Result<String> {
+        let path = self.machine_id_path();
+        match std::fs::read_to_string(&path) {
+            Ok(id) if is_machine_id(id.trim()) => return Ok(id.trim().to_string()),
+            Ok(_) => {
+                tracing::warn!(path = %path.display(), "machine id is unusable; making a new one");
+            }
+            Err(e) if e.kind() == std::io::ErrorKind::NotFound => {}
+            Err(e) => return Err(e.into()),
+        }
+        let mut bytes = [0u8; 16];
+        use std::io::Read as _;
+        std::fs::File::open("/dev/urandom")?.read_exact(&mut bytes)?;
+        let id: String = bytes.iter().map(|b| format!("{b:02x}")).collect();
+        let parent = path
+            .parent()
+            .ok_or_else(|| Error::Other("machine id path has no parent".into()))?;
+        std::fs::create_dir_all(parent)?;
+        let tmp = path.with_extension(format!("tmp-{}", std::process::id()));
+        std::fs::write(&tmp, format!("{id}\n"))?;
+        std::fs::File::open(&tmp)?.sync_all()?;
+        std::fs::rename(&tmp, &path)?;
+        std::fs::File::open(parent)?.sync_all()?;
+        Ok(id)
+    }
+
     /// Persistent state: inode map / cache index DB lives here.
     pub fn state_dir(&self) -> PathBuf {
         // `state_dir` is Linux-only in `directories`; fall back to data dir.
@@ -449,6 +594,12 @@ impl AppDirs {
     }
 }
 
+/// Whether `id` is what [`AppDirs::machine_id`] writes: 32 lowercase hex
+/// digits.
+fn is_machine_id(id: &str) -> bool {
+    id.len() == 32 && id.bytes().all(|b| matches!(b, b'0'..=b'9' | b'a'..=b'f'))
+}
+
 /// Make `dir` owner-only (`0700`). These directories contain decrypted bytes,
 /// plaintext names, and an authenticated control socket, so failure is fatal.
 fn restrict_dir(dir: &Path) -> Result<()> {
@@ -504,6 +655,28 @@ mod tests {
         std::fs::metadata(p).unwrap().permissions().mode() & 0o777
     }
 
+    /// A damaged config must not be replaced by defaults the next time a
+    /// setting changes (`docs/BUGS.md` B223).
+    #[test]
+    fn an_unreadable_config_is_never_written_over() {
+        let dir = std::env::temp_dir().join(format!(
+            "pdfs-cfg-guard-{}-{:?}",
+            std::process::id(),
+            std::thread::current().id()
+        ));
+        let _ = std::fs::remove_dir_all(&dir);
+        std::fs::create_dir_all(&dir).unwrap();
+        let path = dir.join("config.json");
+
+        assert!(refuse_to_replace_unreadable(&path).is_ok(), "no file yet");
+        std::fs::write(&path, serde_json::to_vec(&AppConfig::default()).unwrap()).unwrap();
+        assert!(refuse_to_replace_unreadable(&path).is_ok());
+        std::fs::write(&path, br#"{"mountpoint": "/home/me/Pro"#).unwrap();
+        assert!(refuse_to_replace_unreadable(&path).is_err(), "truncated");
+
+        let _ = std::fs::remove_dir_all(&dir);
+    }
+
     /// `docs/BUGS.md` B6. A permissive mode here is not a cosmetic problem: these
     /// directories hold decrypted content, a plaintext index of every node name,
     /// and the control socket that commands the daemon's session.
@@ -571,8 +744,8 @@ mod tests {
     #[test]
     fn test_app_config_serialization() {
         let config = AppConfig {
-            app_version: "external-drive-test-client@1.0.0".to_string(),
-            user_agent: "test-agent/1.0".to_string(),
+            app_version: Some("external-drive-test-client@1.0.0".to_string()),
+            user_agent: Some("test-agent/1.0".to_string()),
             cache_budget: Some(1234),
             upload_limit: Some(500_000),
             download_limit: None,
@@ -589,22 +762,69 @@ mod tests {
                 descending: true,
                 folders_first: false,
             },
+            window: WindowState {
+                width: 1200,
+                height: 800,
+                maximized: true,
+            },
             tray_hidden: true,
             language: Some("de".to_string()),
             online_map: true,
             local_first: Some(false),
+            update_check: true,
+            update_last_checked: Some(1_760_000_000),
+            update_latest: Some("3.6.0".to_string()),
         };
         let json = serde_json::to_string(&config).unwrap();
         let decoded: AppConfig = serde_json::from_str(&json).unwrap();
-        assert_eq!(decoded.app_version, "external-drive-test-client@1.0.0");
-        assert_eq!(decoded.user_agent, "test-agent/1.0");
+        assert_eq!(
+            decoded.resolved_app_version(),
+            "external-drive-test-client@1.0.0"
+        );
+        assert_eq!(decoded.resolved_user_agent(), "test-agent/1.0");
         assert_eq!(decoded.proton_theme, Some(true));
         assert!(decoded.tray_hidden);
         assert!(decoded.online_map);
+        assert!(decoded.update_check);
+        assert_eq!(decoded.update_last_checked, Some(1_760_000_000));
+        assert_eq!(decoded.update_latest.as_deref(), Some("3.6.0"));
         assert_eq!(decoded.language.as_deref(), Some("de"));
         assert_eq!(decoded.upload_limit, Some(500_000));
         assert_eq!(decoded.download_limit, None);
         assert_eq!(decoded.files_view, config.files_view);
+        assert_eq!(decoded.window, config.window);
+    }
+
+    #[test]
+    fn a_config_without_a_window_opens_at_the_default_size() {
+        let decoded: AppConfig =
+            serde_json::from_str(r#"{"app_version":"a","user_agent":"b"}"#).unwrap();
+        assert_eq!(decoded.window, WindowState::default());
+        let partial: WindowState = serde_json::from_str(r#"{"maximized":true}"#).unwrap();
+        assert_eq!((partial.width, partial.height), (980, 680));
+        assert!(partial.maximized);
+    }
+
+    #[test]
+    fn a_window_saved_too_small_opens_at_the_default_size() {
+        let tiny = WindowState {
+            width: 0,
+            height: 500,
+            maximized: true,
+        };
+        assert_eq!(
+            tiny.usable(),
+            WindowState {
+                maximized: true,
+                ..WindowState::default()
+            }
+        );
+        let fine = WindowState {
+            width: 640,
+            height: 480,
+            maximized: false,
+        };
+        assert_eq!(fine.usable(), fine);
     }
 
     #[test]
@@ -628,8 +848,55 @@ mod tests {
     #[test]
     fn test_default_app_config() {
         let default_config = AppConfig::default();
-        assert_eq!(default_config.app_version, APP_VERSION);
-        assert_eq!(default_config.user_agent, USER_AGENT);
+        assert_eq!(default_config.resolved_app_version(), APP_VERSION);
+        assert_eq!(default_config.resolved_user_agent(), USER_AGENT);
+    }
+
+    #[test]
+    fn the_client_identity_follows_the_release() {
+        let version = env!("CARGO_PKG_VERSION");
+        assert_eq!(
+            APP_VERSION,
+            format!("external-drive-linux@{version}-stable")
+        );
+        assert_eq!(USER_AGENT, format!("proton-drive-linux/{version}"));
+    }
+
+    #[test]
+    fn an_old_config_with_the_fixed_identity_follows_the_release() {
+        // Every config written up to 3.1.0 holds these two values, so they must
+        // not pin the identity once Proton retires 0.1.0.
+        let json = format!(
+            r#"{{"app_version":"{LEGACY_APP_VERSION}","user_agent":"{LEGACY_USER_AGENT}","tray_hidden":true}}"#
+        );
+        let decoded: AppConfig = serde_json::from_str(&json).unwrap();
+        assert_eq!(decoded.resolved_app_version(), APP_VERSION);
+        assert_eq!(decoded.resolved_user_agent(), USER_AGENT);
+        assert!(decoded.tray_hidden, "the rest of the config survives");
+
+        let saved = serde_json::to_string(&decoded).unwrap();
+        assert!(!saved.contains("app_version"), "{saved}");
+        assert!(!saved.contains("user_agent"), "{saved}");
+    }
+
+    #[test]
+    fn a_hand_set_client_identity_is_kept() {
+        let json = r#"{"app_version":"external-drive-linux@9.9.9-beta","user_agent":"custom/1"}"#;
+        let decoded: AppConfig = serde_json::from_str(json).unwrap();
+        assert_eq!(
+            decoded.resolved_app_version(),
+            "external-drive-linux@9.9.9-beta"
+        );
+        assert_eq!(decoded.resolved_user_agent(), "custom/1");
+        let saved = serde_json::to_string(&decoded).unwrap();
+        assert!(saved.contains("external-drive-linux@9.9.9-beta"), "{saved}");
+    }
+
+    #[test]
+    fn a_config_without_a_client_identity_loads() {
+        let decoded: AppConfig = serde_json::from_str("{}").unwrap();
+        assert_eq!(decoded.resolved_app_version(), APP_VERSION);
+        assert_eq!(decoded.resolved_user_agent(), USER_AGENT);
     }
 
     #[test]
@@ -688,6 +955,15 @@ mod tests {
         assert_eq!(decoded.conflict_sweep, Some(SweepMode::Enforce));
     }
 
+    #[test]
+    fn a_machine_id_is_32_lowercase_hex_digits() {
+        assert!(is_machine_id("0123456789abcdef0123456789abcdef"));
+        assert!(!is_machine_id("0123456789ABCDEF0123456789ABCDEF"));
+        assert!(!is_machine_id("0123456789abcdef"));
+        assert!(!is_machine_id("../../../../etc/passwd/0123456789"));
+        assert!(!is_machine_id(""));
+    }
+
     #[test]
     fn a_config_predating_ignore_patterns_still_loads() {
         // Every installed config on disk looks like this; the field must not be

crates/pdfs-core/src/control.rs

@@ -344,6 +344,17 @@ pub enum Request {
     /// or a mirror synced folder), and the move is still made on Proton Drive
     /// without transferring content. Replies with [`Response::Ok`].
     Move { path: String, new_parent: String },
+    /// Copy a file or folder into a folder on Proton Drive, without
+    /// downloading or uploading it. Both `path` and `new_parent` are
+    /// mountpoint-relative, or absolute paths inside My files. A name already
+    /// taken in `new_parent` gets the next free ` (n)` suffix. Replies with
+    /// [`Response::Ok`].
+    Copy { path: String, new_parent: String },
+    /// Ask Proton Drive how much the folder at mountpoint-relative `path`
+    /// holds. Replies with [`Response::FolderSize`].
+    FolderSize { path: String },
+    /// The by-uid twin of [`Request::FolderSize`].
+    FolderSizeByUid { uid: String },
     /// Trash a file or folder. `path` is mountpoint-relative. Replies with
     /// [`Response::Ok`].
     Delete { path: String },
@@ -446,6 +457,13 @@ pub enum Request {
     /// of registering a duplicate. `uid: None` clears the pin.
     /// Replies with [`Response::Ok`].
     AdoptDevice { uid: Option<String> },
+    /// Move every folder another device backs up into this machine's own
+    /// device, as server-side moves on the main volume. The other device stays
+    /// registered, without those folders. Sync folders here that already track
+    /// one of them follow it to its new share. Nothing is downloaded: the moved
+    /// folders are then offered by [`Request::ListRestorableFolders`].
+    /// Replies with [`Response::Ok`].
+    MigrateDevice { uid: String },
 
     // ---- device folder sync ----------------------------------
     /// Add a local folder to this machine's device, uploading its tree and
@@ -462,6 +480,11 @@ pub enum Request {
     /// Pause or resume one mirror folder's reconcile, independent of the
     /// global pause. Persisted until resumed. Replies with [`Response::Ok`].
     SetSyncFolderPaused { id: i64, paused: bool },
+    /// Forget what a mirror folder synced before, so its next pass compares
+    /// both sides afresh: what is on one side only is copied to the other, and
+    /// a file that differs keeps both versions. Nothing is deleted. Replies
+    /// with [`Response::Ok`].
+    ResetSyncFolder { id: i64 },
     /// Force a reconcile pass: one folder by id, or all when `id` is `None`.
     /// Replies with [`Response::Ok`].
     SyncNow { id: Option<i64> },
@@ -589,6 +612,24 @@ pub enum Request {
     RemovePublicLink { path: String, id: String },
     /// The by-uid twin of [`Request::RemovePublicLink`].
     RemovePublicLinkByUid { uid: String, id: String },
+    /// Change the public link `id` on the node at `path`, keeping its URL.
+    /// `role` is "viewer" or "editor", or `None` to keep the current one.
+    /// Replies with [`Response::PublicLink`].
+    UpdatePublicLink {
+        path: String,
+        id: String,
+        role: Option<String>,
+        password: LinkChange<String>,
+        expires: LinkChange<i64>,
+    },
+    /// The by-uid twin of [`Request::UpdatePublicLink`].
+    UpdatePublicLinkByUid {
+        uid: String,
+        id: String,
+        role: Option<String>,
+        password: LinkChange<String>,
+        expires: LinkChange<i64>,
+    },
     /// Stop sharing the node at `path`: remove its public link, every pending
     /// invitation and every member. Each removal is attempted even if an
     /// earlier one fails. Replies with [`Response::Ok`], or an error naming
@@ -1068,6 +1109,18 @@ pub struct PublicLinkInfo {
     pub created: i64,
 }
 
+/// What [`Request::UpdatePublicLink`] does with one option of a link: its
+/// custom password or its expiry.
+#[derive(Serialize, Deserialize, Debug, Clone, PartialEq, Eq)]
+pub enum LinkChange<T> {
+    /// Leave the option as it is.
+    Keep,
+    /// Remove the option: no custom password, or no expiry.
+    Remove,
+    /// Set the option to this value.
+    Set(T),
+}
+
 /// One invitation addressed to me (in [`Response::Invitations`]).
 #[derive(Serialize, Deserialize, Debug, Clone)]
 pub struct InvitationInfo {
@@ -1162,6 +1215,7 @@ pub enum ActivityKind {
     Sync,
     Rename,
     Move,
+    Copy,
     CreateFolder,
     Trash,
     Restore,
@@ -1218,6 +1272,12 @@ pub struct JobItem {
     /// Steps known to need doing, or `0` when unknown (indeterminate progress).
     /// May *grow* mid-job as more work is discovered.
     pub total: u64,
+    /// Housekeeping that changes nothing in the user's files: a mirror folder
+    /// scan that finds nothing to do yet, an index rebuild, a cache check. Front
+    /// ends may show it, but should not report the drive as busy over it. Absent
+    /// from older daemons, which never set it.
+    #[serde(default)]
+    pub background: bool,
 }
 
 /// One in-flight transfer in a [`Response::Transfers`] snapshot.
@@ -1247,8 +1307,15 @@ pub struct DirEntry {
     pub size: u64,
     /// Modification time, epoch seconds.
     pub modified: i64,
-    /// Whether the file is pinned to this device.
+    /// Whether the node is pinned to this device, on its own or through a
+    /// pinned folder above it.
     pub pinned: bool,
+    /// Whether the node is kept on this device because a folder above it is
+    /// pinned. Such a node cannot be unpinned on its own. Set in
+    /// [`Request::ListDir`] listings only. Defaulted for wire-compat with
+    /// daemons predating the field.
+    #[serde(default)]
+    pub pinned_by_folder: bool,
     /// Whether the file's full content is present in the local cache (a current,
     /// non-stale blob). Always false for folders. Defaulted for wire-compat with
     /// clients/daemons predating the field.
@@ -1571,6 +1638,10 @@ pub struct RedateSummary {
     /// name implies)` — what a dry run is read for.
     #[serde(default)]
     pub samples: Vec<(String, i64, i64)>,
+    /// Why the run as a whole failed, when it did. The counts are then
+    /// empty: the run never got to the photos.
+    #[serde(default)]
+    pub error: Option<String>,
 }
 
 /// How a Google Photos Takeout import is going, or how the last one ended
@@ -1600,6 +1671,10 @@ pub struct ImportSummary {
     pub bytes: u64,
     /// True when the run stopped early because it was cancelled.
     pub cancelled: bool,
+    /// Why the run as a whole failed, when it did, such as an archive that
+    /// is not a zip. The counts are then empty.
+    #[serde(default)]
+    pub error: Option<String>,
 }
 
 /// One album in a [`Response::Albums`] listing.
@@ -1837,6 +1912,27 @@ pub fn pending_summary(uploads: u64, changes: u64) -> Option<String> {
     }
 }
 
+/// Whether the daemon that reported `version` in a [`Response::Status`] is an
+/// older release than this build. Installing a package replaces the binaries
+/// but leaves the running user service on the old one, which keeps its bugs
+/// until it restarts, while the app and the CLI already describe the new
+/// release (#33). Empty means a daemon from before the field, so older too.
+///
+/// Only older counts. A newer daemon means this front-end is the one still
+/// running from before the upgrade, and restarting the service would not help.
+pub fn daemon_outdated(version: &str) -> bool {
+    fn parse(v: &str) -> Option<(u64, u64, u64)> {
+        let mut parts = v.split('.').map(|p| p.parse().ok());
+        let parsed = (parts.next()??, parts.next()??, parts.next()??);
+        parts.next().is_none().then_some(parsed)
+    }
+    match (parse(version), parse(env!("CARGO_PKG_VERSION"))) {
+        (Some(running), Some(this)) => running < this,
+        (None, _) => version.is_empty(),
+        (Some(_), None) => false,
+    }
+}
+
 /// One worker thread in a [`Diagnostics`] report.
 #[derive(Serialize, Deserialize, Debug, Clone)]
 pub struct WorkerState {
@@ -1884,6 +1980,29 @@ pub struct Diagnostics {
     pub control_handler_limit: usize,
     /// Queued mutations not yet drained.
     pub pending_ops: u64,
+    /// The folder-sync engine. `None` from a daemon that predates the field.
+    #[serde(default)]
+    pub sync: Option<SyncEngineState>,
+}
+
+/// What the folder-sync engine is doing, for [`Diagnostics`].
+///
+/// The engine is one thread that runs every synced folder's passes in turn.
+/// Dead or stuck, it looked exactly like an idle one: workers idle, nothing
+/// queued, nothing in the journal (`docs/BUGS.md` B259).
+#[derive(Serialize, Deserialize, Debug, Clone, Default)]
+pub struct SyncEngineState {
+    /// Whether the engine thread is running. Once it has ended, nothing syncs
+    /// until the daemon restarts.
+    pub running: bool,
+    /// The synced folder whose pass is running, if one is.
+    pub pass_folder: Option<i64>,
+    /// How long that pass has been running.
+    pub pass_age_secs: u64,
+    /// How long since that pass last reported progress.
+    pub pass_idle_secs: u64,
+    /// Passes that ended in a panic since the daemon started.
+    pub panics: u64,
 }
 
 /// The daemon's reply to a [`Request`].
@@ -1946,6 +2065,21 @@ pub enum Response {
         /// resumed, or not paused.
         #[serde(default)]
         paused_until: Option<i64>,
+        /// True when Proton refused the session itself (refresh token refused,
+        /// account deleted or disabled). `online` is false then too, but no
+        /// connection brings it back: only signing in again does.
+        #[serde(default)]
+        session_expired: bool,
+        /// True while the keyring refuses the session's refreshed tokens. The
+        /// daemon keeps retrying; until it succeeds, a reboot signs the user
+        /// out.
+        #[serde(default)]
+        tokens_unsaved: bool,
+        /// The release of the daemon that answered. A package upgrade does not
+        /// restart the user service, so it can be older than the front-end
+        /// asking; daemons before 3.3.0 omit it, which reads as empty.
+        #[serde(default)]
+        version: String,
     },
     /// A human-readable success message.
     Ok { message: String },
@@ -2121,9 +2255,14 @@ pub enum Response {
         entries: Vec<ShareEntry>,
         link: Option<PublicLinkInfo>,
     },
-    /// A freshly created public link, carrying the shareable URL (reply to
-    /// [`Request::CreatePublicLink`]).
+    /// A freshly created or changed public link, carrying the shareable URL
+    /// (reply to [`Request::CreatePublicLink`] and
+    /// [`Request::UpdatePublicLink`]).
     PublicLink { link: PublicLinkInfo },
+    /// What a folder holds on Proton Drive (reply to [`Request::FolderSize`]):
+    /// the bytes on storage and the number of items below it, folders and
+    /// trashed items included.
+    FolderSize { size: u64, items: u64 },
     /// Invitations addressed to me (reply to [`Request::ListInvitations`]).
     Invitations { items: Vec<InvitationInfo> },
     /// Saved public links (reply to [`Request::ListBookmarks`]).
@@ -2589,6 +2728,27 @@ mod tests {
         );
     }
 
+    /// #33: a daemon left running over an upgrade is named as older, also when
+    /// it predates the version field, but a newer one is not, since restarting
+    /// the service cannot bring it closer to this build.
+    #[test]
+    fn only_an_older_daemon_is_outdated() {
+        assert!(!daemon_outdated(env!("CARGO_PKG_VERSION")));
+        assert!(daemon_outdated(""));
+        assert!(daemon_outdated("0.9.9"));
+        assert!(!daemon_outdated("999.0.0"));
+        assert!(!daemon_outdated("not-a-version"));
+        let old: Response = serde_json::from_str(
+            r#"{"Status":{"username":"u","mountpoint":"/m","pinned":0,
+                "used":0,"budget":0,"pins":[]}}"#,
+        )
+        .unwrap();
+        let Response::Status { version, .. } = old else {
+            panic!("not a status: {old:?}");
+        };
+        assert!(daemon_outdated(&version));
+    }
+
     /// The mutation requests must survive a line-delimited JSON round-trip, since
     /// that is exactly how they cross the control socket.
     #[test]
@@ -2602,6 +2762,10 @@ mod tests {
                 path: "a/b.txt".into(),
                 new_parent: "d".into(),
             },
+            Request::Copy {
+                path: "a/b.txt".into(),
+                new_parent: "d".into(),
+            },
             Request::Delete {
                 path: "a/b.txt".into(),
             },
@@ -3073,6 +3237,7 @@ mod tests {
                 id: 3,
                 paused: true,
             },
+            Request::ResetSyncFolder { id: 3 },
             Request::SetBandwidthLimits {
                 upload: 1_000_000,
                 download: 0,
@@ -3082,6 +3247,9 @@ mod tests {
                 uid: Some("dev-1".into()),
             },
             Request::AdoptDevice { uid: None },
+            Request::MigrateDevice {
+                uid: "dev-2".into(),
+            },
             Request::ListRestorableFolders,
             Request::RestoreSyncFolders {
                 items: vec![RestoreItem {
@@ -3159,6 +3327,24 @@ mod tests {
                 uid: "vol~link".into(),
                 id: "url-1".into(),
             },
+            Request::UpdatePublicLink {
+                path: "a/b".into(),
+                id: "url-1".into(),
+                role: Some("editor".into()),
+                password: LinkChange::Set("pw".into()),
+                expires: LinkChange::Remove,
+            },
+            Request::UpdatePublicLinkByUid {
+                uid: "vol~link".into(),
+                id: "url-1".into(),
+                role: None,
+                password: LinkChange::Keep,
+                expires: LinkChange::Set(1_700_000_000),
+            },
+            Request::FolderSize { path: "a".into() },
+            Request::FolderSizeByUid {
+                uid: "vol~link".into(),
+            },
             Request::ListSharedByMe,
             Request::ListActivity { limit: 100 },
             Request::ListSharedWithMe,
@@ -3533,6 +3719,16 @@ mod tests {
                 },
                 "RemovePublicLinkByUid",
             ),
+            (
+                Request::UpdatePublicLinkByUid {
+                    uid: "vol~link".into(),
+                    id: "link".into(),
+                    role: None,
+                    password: LinkChange::Keep,
+                    expires: LinkChange::Keep,
+                },
+                "UpdatePublicLinkByUid",
+            ),
             (
                 Request::StopSharingByUid {
                     uid: "vol~link".into(),
@@ -3558,6 +3754,7 @@ mod tests {
                 | Request::RemoveShareEntryByUid { uid, .. }
                 | Request::CreatePublicLinkByUid { uid, .. }
                 | Request::RemovePublicLinkByUid { uid, .. }
+                | Request::UpdatePublicLinkByUid { uid, .. }
                 | Request::StopSharingByUid { uid } => uid,
                 other => panic!("decoded into the wrong dispatch variant: {other:?}"),
             };
@@ -3566,6 +3763,25 @@ mod tests {
         }
     }
 
+    #[test]
+    fn a_link_update_names_what_it_keeps_removes_and_sets() {
+        let request = Request::UpdatePublicLink {
+            path: "a/b".into(),
+            id: "url-1".into(),
+            role: None,
+            password: LinkChange::Keep,
+            expires: LinkChange::Set(1_700_000_000),
+        };
+        assert_eq!(
+            serde_json::to_string(&request).unwrap(),
+            r#"{"UpdatePublicLink":{"path":"a/b","id":"url-1","role":null,"password":"Keep","expires":{"Set":1700000000}}}"#
+        );
+        assert_eq!(
+            serde_json::to_string(&LinkChange::<String>::Remove).unwrap(),
+            r#""Remove""#
+        );
+    }
+
     #[test]
     fn open_file_accepts_a_request_from_a_client_predating_the_uid_field() {
         let legacy = r#"{"OpenFile":{"path":"Documents/ONBOARDING.md"}}"#;

crates/pdfs-core/src/db/local.rs

@@ -111,9 +111,80 @@ impl Db {
         )?;
         let count: i64 = tx.query_row("SELECT COUNT(*) FROM local_files", [], |r| r.get(0))?;
         tx.commit()?;
+        drop(conn);
+        self.compact_search_indexes_if_due(finished_at)?;
         Ok(count)
     }
 
+    /// Close a scan that did not see everything: it stopped at the entry cap,
+    /// or a batch failed to write. Nothing is pruned, since a path it missed is
+    /// not a path that is gone; the next complete scan prunes. Returns the
+    /// number of indexed entries.
+    ///
+    /// Pruning after such a scan dropped every entry it had not reached, and
+    /// the next scan put them back. That churn is most of what grew
+    /// `local_fts` to 16 times its size (`docs/BUGS.md` B217).
+    pub fn local_finish_partial_scan(&self, finished_at: i64) -> Result<i64> {
+        let conn = self.conn.lock();
+        conn.execute(
+            "INSERT INTO sync_state (key, value) VALUES ('local_indexed_at', ?1)
+             ON CONFLICT(key) DO UPDATE SET value = excluded.value",
+            [finished_at.to_string()],
+        )?;
+        let count: i64 = conn.query_row("SELECT COUNT(*) FROM local_files", [], |r| r.get(0))?;
+        Ok(count)
+    }
+
+    /// Compact both full-text indexes, at most once a day.
+    ///
+    /// FTS5 keeps a deleted entry's data until the segments holding it are
+    /// merged, and with the few large segments these indexes settle into that
+    /// is close to never. Every file the local scan sees disappear or appear
+    /// leaves some behind, and every node row the tree replaces does too: on
+    /// one machine `local_fts` held 317 MiB for 40,000 paths, against 20 MiB
+    /// rebuilt, and a search took four times as long (`docs/BUGS.md` B217).
+    ///
+    /// `local_fts` is rebuilt from `local_files`, which also drops anything
+    /// left over, and `nodes_fts`, which has no content table to rebuild from,
+    /// is merged into one segment. Each runs in its own transaction on the
+    /// write connection, about half a second on an index that size; once a
+    /// day keeps the leftovers small without paying that at every scan.
+    pub fn compact_search_indexes_if_due(&self, now: i64) -> Result<()> {
+        const EVERY_SECS: i64 = 24 * 60 * 60;
+        let last: i64 = self
+            .read()
+            .query_row(
+                "SELECT value FROM sync_state WHERE key = 'fts_compacted_at'",
+                [],
+                |row| row.get::<_, String>(0),
+            )
+            .optional()?
+            .and_then(|v| v.parse().ok())
+            .unwrap_or(0);
+        if now - last < EVERY_SECS {
+            return Ok(());
+        }
+        let started = std::time::Instant::now();
+        {
+            let conn = self.conn.lock();
+            conn.execute("INSERT INTO local_fts(local_fts) VALUES('rebuild')", [])?;
+        }
+        {
+            let conn = self.conn.lock();
+            conn.execute("INSERT INTO nodes_fts(nodes_fts) VALUES('optimize')", [])?;
+            conn.execute(
+                "INSERT INTO sync_state (key, value) VALUES ('fts_compacted_at', ?1)
+                 ON CONFLICT(key) DO UPDATE SET value = excluded.value",
+                [now.to_string()],
+            )?;
+        }
+        tracing::info!(
+            elapsed_ms = started.elapsed().as_millis() as u64,
+            "compacted the search indexes"
+        );
+        Ok(())
+    }
+
     /// When the last local scan completed (epoch seconds), or `None` if the index
     /// has never been built. The daemon uses this to decide whether a fresh mount
     /// needs an immediate rescan or can serve the existing index.

crates/pdfs-core/src/db/maintenance.rs

@@ -91,8 +91,13 @@ impl Db {
     /// Returns an empty vector when the database is sound; otherwise each entry
     /// is one problem SQLite found. Read-only and safe against a live daemon,
     /// though it reads every page, so it is not free on a large file.
+    ///
+    /// Runs on a read connection: it reads every page, which took 34 s on a
+    /// 567 MiB file, and on the write connection every write in the daemon
+    /// waited that long behind it (`docs/BUGS.md` B218). WAL lets it read a
+    /// consistent snapshot while the writer goes on.
     pub fn integrity_check(&self) -> Result<Vec<String>> {
-        let conn = self.conn.lock();
+        let conn = self.read();
         let mut stmt = conn.prepare("PRAGMA integrity_check")?;
         let rows = stmt.query_map([], |r| r.get::<_, String>(0))?;
         let mut problems = Vec::new();
@@ -107,9 +112,11 @@ impl Db {
         Ok(problems)
     }
 
-    /// Size and row-count snapshot for `pdfs cache inspect`.
+    /// Size and row-count snapshot for `pdfs cache inspect`. On a read
+    /// connection, for the reason [`integrity_check`](Self::integrity_check)
+    /// gives: counting the rows of every table reads most of the file.
     pub fn stats(&self) -> Result<DbStats> {
-        let conn = self.conn.lock();
+        let conn = self.read();
         let page_count: i64 = conn.query_row("PRAGMA page_count", [], |r| r.get(0))?;
         let free_pages: i64 = conn.query_row("PRAGMA freelist_count", [], |r| r.get(0))?;
         let page_size: i64 = conn.query_row("PRAGMA page_size", [], |r| r.get(0))?;
@@ -218,6 +225,40 @@ mod tests {
         assert!(db.integrity_check().unwrap().is_empty());
     }
 
+    /// `pdfs diagnose` and `pdfs cache inspect` read the whole file. Behind the
+    /// write lock they froze every write in the daemon for as long as that
+    /// took (`docs/BUGS.md` B218).
+    #[test]
+    fn the_integrity_check_and_stats_do_not_wait_for_the_writer() {
+        let path = std::env::temp_dir().join(format!(
+            "pdfs-check-{}-{}.db",
+            std::process::id(),
+            std::time::SystemTime::now()
+                .duration_since(std::time::UNIX_EPOCH)
+                .unwrap()
+                .as_nanos()
+        ));
+        let db = std::sync::Arc::new(Db::open(&path).unwrap());
+        let writer = db.conn.lock();
+        let (tx, rx) = std::sync::mpsc::channel();
+        let reader = std::sync::Arc::clone(&db);
+        std::thread::spawn(move || {
+            let checked = reader.integrity_check().map(|p| p.is_empty());
+            let counted = reader.stats().map(|s| s.page_count > 0);
+            let _ = tx.send((checked.ok(), counted.ok()));
+        });
+        let answer = rx.recv_timeout(std::time::Duration::from_secs(10));
+        drop(writer);
+        assert_eq!(answer.ok(), Some((Some(true), Some(true))));
+        drop(db);
+        for suffix in ["", "-wal", "-shm"] {
+            let mut file = path.as_os_str().to_owned();
+            file.push(suffix);
+            let _ = std::fs::remove_file(std::path::PathBuf::from(file));
+        }
+        let _ = std::fs::remove_file(path.with_extension("db.lock"));
+    }
+
     #[test]
     fn stats_report_the_schema_and_the_known_tables() {
         let db = Db::open_in_memory().unwrap();

crates/pdfs-core/src/db/migrations.rs

@@ -11,7 +11,7 @@ use super::Db;
 use crate::Result;
 
 /// Current schema version. Bump on every forward migration added below.
-pub(super) const SCHEMA_VERSION: i64 = 42;
+pub(super) const SCHEMA_VERSION: i64 = 44;
 
 impl Db {
     pub(super) fn migrate(&self) -> Result<()> {
@@ -440,6 +440,33 @@ impl Db {
                 tx.execute_batch(MIGRATION_V42)?;
             }
         }
+        if current < 43 {
+            let has_ops: bool = tx.query_row(
+                "SELECT COUNT(*) FROM sqlite_master WHERE type = 'table' AND name = 'pending_op'",
+                [],
+                |row| row.get::<_, i64>(0),
+            )? > 0;
+            if has_ops {
+                tx.execute_batch(MIGRATION_V43)?;
+            }
+        }
+        if current < 44 {
+            // Same guards as V26-V42.
+            let has_column: bool = tx.query_row(
+                "SELECT COUNT(*) FROM pragma_table_info('sync_entry') \
+                 WHERE name = 'remote_revision_id'",
+                [],
+                |row| row.get::<_, i64>(0),
+            )? > 0;
+            let has_entries: bool = tx.query_row(
+                "SELECT COUNT(*) FROM sqlite_master WHERE type = 'table' AND name = 'sync_entry'",
+                [],
+                |row| row.get::<_, i64>(0),
+            )? > 0;
+            if has_entries && !has_column {
+                tx.execute_batch(MIGRATION_V44)?;
+            }
+        }
         tx.execute(
             "INSERT INTO sync_state (key, value) VALUES ('schema_version', ?1)
              ON CONFLICT(key) DO UPDATE SET value = excluded.value",
@@ -1330,3 +1357,28 @@ const MIGRATION_V42: &str = "
 ALTER TABLE pending_op ADD COLUMN sent_sha1 TEXT;
 ALTER TABLE pending_op ADD COLUMN sent_to TEXT;
 ";
+
+/// Schema v43: queued ops by kind and name.
+///
+/// Before each create, rename and trash the drain asks whether a queued trash
+/// or rename holds the name it wants, and a released name wakes the ops
+/// waiting for it. Each of those scanned the whole queue, so a large offline
+/// batch made draining it quadratic. The kind leads, so a lookup of every
+/// queued rename uses the index too.
+const MIGRATION_V43: &str = "
+CREATE INDEX IF NOT EXISTS pending_op_kind_name ON pending_op(kind, name);
+";
+
+/// Schema v44: a synced file's baseline remembers the revision it was synced
+/// at.
+///
+/// A mirrored file edited here is uploaded as a new revision of whatever is
+/// current on Drive, and another computer syncing the same folder may have
+/// committed one since this pass looked. The revision id is what the upload
+/// checks first, so that edit becomes a conflict copy instead of being
+/// replaced (B249). `NULL` means "this row predates the column", and the check
+/// falls back to the modification time and size; each row gains a real value
+/// the next time its path is synced.
+const MIGRATION_V44: &str = "
+ALTER TABLE sync_entry ADD COLUMN remote_revision_id TEXT;
+";

crates/pdfs-core/src/db/mod.rs

@@ -179,6 +179,45 @@ impl Drop for Reader<'_> {
     }
 }
 
+/// The write connection with `synchronous=FULL`, back to NORMAL on drop.
+///
+/// NORMAL in WAL mode keeps a commit across a crash of the process but not
+/// across a power loss: the WAL is synced only at checkpoints. That is fine for
+/// metadata the next listing re-fetches, and not for the queue. A staged blob
+/// is synced before its op is queued, and the op row is what makes it
+/// reachable; losing that row loses a write `close()` already reported as
+/// done. A FULL commit syncs the WAL, which covers every NORMAL commit before
+/// it as well.
+pub(super) struct Durable<'a>(parking_lot::MutexGuard<'a, Connection>);
+
+impl<'a> Durable<'a> {
+    pub(super) fn new(conn: parking_lot::MutexGuard<'a, Connection>) -> Result<Self> {
+        conn.pragma_update(None, "synchronous", "FULL")?;
+        Ok(Self(conn))
+    }
+}
+
+impl std::ops::Deref for Durable<'_> {
+    type Target = Connection;
+
+    fn deref(&self) -> &Connection {
+        &self.0
+    }
+}
+
+impl std::ops::DerefMut for Durable<'_> {
+    fn deref_mut(&mut self) -> &mut Connection {
+        &mut self.0
+    }
+}
+
+impl Drop for Durable<'_> {
+    fn drop(&mut self) {
+        // A failure leaves the writer at FULL: slower, never less safe.
+        let _ = self.0.pragma_update(None, "synchronous", "NORMAL");
+    }
+}
+
 /// Open a second connection to the same file for reads only.
 ///
 /// `SQLITE_OPEN_READ_ONLY` plus `query_only` is belt and braces: the flag stops
@@ -216,18 +255,34 @@ impl Db {
         let conn = match Self::open_configured(path) {
             Ok(conn) => conn,
             Err(e) if is_corrupt(&e) => {
-                // Every byte in here is derived from the account or from the
-                // content cache directory, so the recovery is to start over —
-                // loudly, and keeping the damaged file for a post-mortem rather
-                // than deleting evidence.
+                // Most of what is in here is derived from the account and is
+                // fetched again. The queue is not: it holds writes accepted
+                // here that Drive does not have yet, and the mirror baselines
+                // and pins are this machine's alone. So the damaged file is
+                // moved aside, kept as evidence, and those tables are copied
+                // out of it into the new one as far as SQLite can still read
+                // them (`docs/BUGS.md` B216).
                 tracing::error!(
                     db = %path.display(),
                     error = %e,
-                    "cache database is corrupt — moving it aside and rebuilding \
-                     (metadata will be re-fetched; no user data is stored here)"
+                    "cache database is corrupt; moving it aside, rebuilding, and \
+                     copying the upload queue, sync baselines and pins out of it"
                 );
-                quarantine_corrupt_db(path)?;
-                Self::open_configured(path)?
+                let damaged = quarantine_corrupt_db(path)?;
+                let conn = Self::open_configured(path)?;
+                for (table, result) in salvage(&conn, &damaged) {
+                    match result {
+                        Ok(rows) => {
+                            tracing::warn!(table, rows, "salvaged from the damaged database")
+                        }
+                        Err(error) => tracing::error!(
+                            table,
+                            %error,
+                            "could not salvage from the damaged database"
+                        ),
+                    }
+                }
+                conn
             }
             Err(e) => return Err(e),
         };
@@ -254,6 +309,12 @@ impl Db {
         Ok(db)
     }
 
+    /// The write connection for a commit that accepts a user's change into
+    /// the queue. See [`Durable`].
+    pub(super) fn durable(&self) -> Result<Durable<'_>> {
+        Durable::new(self.conn.lock())
+    }
+
     /// A connection for a `SELECT`-only method.
     ///
     /// Reads see the last committed state, which is the same thing they saw
@@ -281,7 +342,8 @@ impl Db {
     fn open_configured(path: &Path) -> Result<Connection> {
         let conn = Connection::open(path)?;
         // WAL: readers never block the single writer. NORMAL sync is the
-        // standard durability/throughput tradeoff for WAL.
+        // standard durability/throughput tradeoff for WAL; the queue commits
+        // that need more raise it to FULL for themselves (`Durable`).
         conn.pragma_update(None, "journal_mode", "WAL")?;
         conn.pragma_update(None, "synchronous", "NORMAL")?;
         conn.pragma_update(None, "foreign_keys", "ON")?;
@@ -428,12 +490,96 @@ fn is_corrupt(e: &Error) -> bool {
     )
 }
 
-/// Move a damaged database (and its WAL sidecars) out of the way so the next
-/// open starts from empty.
+/// The tables [`salvage`] copies out of a damaged database, in order, each
+/// with the rows it keeps.
 ///
-/// Renamed rather than deleted: this is a cache, but it is also the only
-/// evidence of what went wrong, and it costs one file the user can remove.
-fn quarantine_corrupt_db(path: &Path) -> Result<()> {
+/// The queue goes with the node rows it names by local id: a create made here
+/// has no other record of its node, and a real node keeps its local id when its
+/// folder is listed again. Those rows come back unlisted, so their folders are
+/// fetched again rather than trusted. Claims are cleared by [`Db::open`] as
+/// after any other crash.
+const SALVAGE: &[(&str, &str)] = &[
+    (
+        "nodes",
+        "lid IN (SELECT lid FROM old.pending_op WHERE lid IS NOT NULL
+                 UNION SELECT parent_lid FROM old.pending_op WHERE parent_lid IS NOT NULL)
+         OR uid LIKE 'local~%'",
+    ),
+    ("pending_op", "1"),
+    ("sync_folder", "1"),
+    ("sync_entry", "1"),
+    ("pins", "1"),
+    ("own_sealed_rev", "1"),
+];
+
+/// Copy what only this machine has out of the damaged database at `damaged`
+/// into the fresh one `conn` just created. Returns how each table went.
+///
+/// Each table is copied in its own transaction, so a table SQLite cannot read
+/// to the end is left out whole rather than half copied, and does not stop
+/// the others. Only the columns both files have are copied, which covers a
+/// file that broke in the middle of an upgrade. The damaged file is opened read
+/// only and left as it was.
+fn salvage(conn: &Connection, damaged: &Path) -> Vec<(&'static str, Result<usize>)> {
+    let uri = format!(
+        "file:{}?mode=ro",
+        damaged
+            .to_string_lossy()
+            .replace('%', "%25")
+            .replace('?', "%3f")
+            .replace('#', "%23")
+    );
+    if let Err(e) = conn.execute("ATTACH DATABASE ?1 AS old", [&uri]) {
+        let e = Error::Db(e);
+        tracing::error!(error = %e, "could not open the damaged database to salvage it");
+        return Vec::new();
+    }
+    let results = SALVAGE
+        .iter()
+        .map(|&(table, rows)| (table, salvage_table(conn, table, rows)))
+        .collect();
+    let _ = conn.execute("UPDATE nodes SET listed = 0", []);
+    if let Err(e) = conn.execute("DETACH DATABASE old", []) {
+        tracing::warn!(error = %e, "could not detach the damaged database");
+    }
+    results
+}
+
+fn salvage_table(conn: &Connection, table: &str, rows: &str) -> Result<usize> {
+    let columns = |schema: &str| -> Result<Vec<String>> {
+        let mut stmt = conn.prepare(&format!("PRAGMA {schema}.table_info({table})"))?;
+        let names = stmt
+            .query_map([], |r| r.get::<_, String>(1))?
+            .collect::<rusqlite::Result<Vec<_>>>()?;
+        Ok(names)
+    };
+    let new = columns("main")?;
+    let shared: Vec<String> = columns("old")?
+        .into_iter()
+        .filter(|c| new.contains(c))
+        .map(|c| format!("\"{c}\""))
+        .collect();
+    if shared.is_empty() {
+        return Ok(0);
+    }
+    let shared = shared.join(", ");
+    let tx = conn.unchecked_transaction()?;
+    let copied = tx.execute(
+        &format!(
+            "INSERT OR IGNORE INTO main.{table} ({shared}) SELECT {shared} FROM old.{table} WHERE {rows}"
+        ),
+        [],
+    )?;
+    tx.commit()?;
+    Ok(copied)
+}
+
+/// Move a damaged database (and its WAL sidecars) out of the way so the next
+/// open starts from empty. Returns where the database itself went.
+///
+/// Renamed rather than deleted: it is the only evidence of what went wrong,
+/// and [`salvage`] reads what only this machine has back out of it.
+fn quarantine_corrupt_db(path: &Path) -> Result<PathBuf> {
     let stamp = std::time::SystemTime::now()
         .duration_since(std::time::UNIX_EPOCH)
         .map(|d| d.as_secs())
@@ -457,7 +603,9 @@ fn quarantine_corrupt_db(path: &Path) -> Result<()> {
             Err(e) => tracing::warn!(file = %from.display(), error = %e, "could not quarantine"),
         }
     }
-    Ok(())
+    let mut kept = path.as_os_str().to_owned();
+    kept.push(format!(".corrupt-{stamp}"));
+    Ok(PathBuf::from(kept))
 }
 
 #[cfg(test)]

crates/pdfs-core/src/db/ops.rs

@@ -252,6 +252,25 @@ const UID_NOW: &str = "COALESCE((SELECT uid FROM nodes WHERE lid = pending_op.li
 const PARENT_NOW: &str =
     "COALESCE((SELECT uid FROM nodes WHERE lid = pending_op.parent_lid), parent_uid)";
 
+/// The `WHERE` terms for a row a drain worker may claim once it falls due: not
+/// claimed already, no other claimed op on the same node, and not under a
+/// folder that has yet to land.
+///
+/// One fragment for [`Db::claim_next_due_op`] and [`Db::earliest_due_at`]. A
+/// row the claim skips but the wait counts is due "now" for as long as it is
+/// held, and every idle worker spun on it (`docs/BUGS.md` B200).
+fn claimable() -> String {
+    format!(
+        "claimed_at = 0
+         AND (parent_uid IS NULL OR substr({PARENT_NOW}, 1, {n}) <> '{v}~')
+         AND uid NOT IN (SELECT uid FROM pending_op WHERE claimed_at <> 0)
+         AND (lid IS NULL OR lid NOT IN (
+           SELECT lid FROM pending_op WHERE claimed_at <> 0 AND lid IS NOT NULL))",
+        v = LOCAL_VOLUME,
+        n = LOCAL_VOLUME.len() + 1,
+    )
+}
+
 /// The volume id given to a node that exists only on this machine, so far. A
 /// real [`NodeUid`] is `{volume}~{link}`, so a placeholder is `local~<lid>` and
 /// round-trips through the same `Display`/parse path as any other uid.
@@ -260,6 +279,45 @@ const PARENT_NOW: &str =
 /// drain replaces it with the uid the server assigns.
 pub const LOCAL_VOLUME: &str = "local";
 
+/// One place a queued create was sent, with when it first was.
+struct SentTarget {
+    parent: String,
+    name: String,
+    at_ms: Option<i64>,
+}
+
+/// The `sent_to` column: `[[parent, name, at_ms], …]`, or `[[parent, name], …]`
+/// as written before the time was kept. `None` when it does not parse.
+fn parse_sent_to(json: Option<&str>) -> Option<Vec<SentTarget>> {
+    #[derive(Deserialize)]
+    #[serde(untagged)]
+    enum Entry {
+        At(String, String, i64),
+        Bare(String, String),
+    }
+    let Some(json) = json else {
+        return Some(Vec::new());
+    };
+    let entries: Vec<Entry> = serde_json::from_str(json).ok()?;
+    Some(
+        entries
+            .into_iter()
+            .map(|entry| match entry {
+                Entry::At(parent, name, at) => SentTarget {
+                    parent,
+                    name,
+                    at_ms: Some(at),
+                },
+                Entry::Bare(parent, name) => SentTarget {
+                    parent,
+                    name,
+                    at_ms: None,
+                },
+            })
+            .collect(),
+    )
+}
+
 /// The uid a node made on this machine goes by until Drive gives it one: its
 /// row's local id under [`LOCAL_VOLUME`].
 ///
@@ -522,7 +580,7 @@ impl Db {
     /// land in the order they were made (`docs/BUGS.md` B141). Should it fail,
     /// [`Db::record_op_failure`] or [`Db::release_op_claim`] drops it.
     pub fn enqueue_op(&self, op: &PendingOp) -> Result<(i64, Option<String>)> {
-        let mut conn = self.conn.lock();
+        let mut conn = self.durable()?;
         let tx = conn.transaction()?;
         let superseded: Option<String> = if op_supersedes(&op.kind) {
             let lid = node_lid(&tx, &op.uid)?;
@@ -579,7 +637,7 @@ impl Db {
         name: &str,
         created_at: i64,
     ) -> Result<(i64, Vec<String>)> {
-        let mut conn = self.conn.lock();
+        let mut conn = self.durable()?;
         let tx = conn.transaction()?;
         let blobs = drop_doomed_ops(&tx, uid)?;
         tx.execute(
@@ -609,7 +667,7 @@ impl Db {
         blob_path: &str,
         meta_json: &str,
     ) -> Result<Option<AttachedBlob>> {
-        let conn = self.conn.lock();
+        let conn = self.durable()?;
         let lid = node_lid(&conn, uid)?;
         let existing: Option<(i64, Option<String>)> = conn
             .query_row(
@@ -672,7 +730,7 @@ impl Db {
         rewrite: impl FnOnce(&str) -> Option<String>,
     ) -> Result<CreateRetired> {
         let (local, real) = (landing.local, landing.real);
-        let mut conn = self.conn.lock();
+        let mut conn = self.durable()?;
         let tx = conn.transaction()?;
         let row: Option<CreateRow> = tx
             .query_row(
@@ -789,12 +847,19 @@ impl Db {
         Ok(())
     }
 
-    /// Record that queued create `id` is being sent to `parent` under `name`.
+    /// Record that queued create `id` is being sent to `parent` under `name`
+    /// at `at_ms`.
     ///
     /// A rename while the op waits rewrites its target, but the file a lost
     /// answer left stays where it was sent. The retry and the trash look
-    /// there too (`docs/BUGS.md` B184).
-    pub fn note_create_target(&self, id: i64, parent: &str, name: &str) -> Result<()> {
+    /// there too (`docs/BUGS.md` B184). A target sent before keeps its first
+    /// time.
+    ///
+    /// A record that does not parse is left as it is rather than replaced
+    /// with this one target: the earlier ones are what the duplicate checks
+    /// look for. Without them a lost answer forks a conflict copy, which
+    /// loses nothing.
+    pub fn note_create_target(&self, id: i64, parent: &str, name: &str, at_ms: i64) -> Result<()> {
         let mut conn = self.conn.lock();
         let tx = conn.transaction()?;
         let sent: Option<String> = tx
@@ -803,15 +868,26 @@ impl Db {
             })
             .optional()?
             .flatten();
-        let mut targets: Vec<(String, String)> = sent
-            .and_then(|json| serde_json::from_str(&json).ok())
-            .unwrap_or_default();
-        let target = (parent.to_string(), name.to_string());
-        if !targets.contains(&target) {
-            targets.push(target);
+        let Some(mut targets) = parse_sent_to(sent.as_deref()) else {
+            tracing::warn!(
+                id,
+                "a queued create's send record does not parse; keeping it"
+            );
+            return Ok(());
+        };
+        if !targets.iter().any(|t| t.parent == parent && t.name == name) {
+            targets.push(SentTarget {
+                parent: parent.to_string(),
+                name: name.to_string(),
+                at_ms: Some(at_ms),
+            });
+            let json: Vec<(&str, &str, i64)> = targets
+                .iter()
+                .map(|t| (t.parent.as_str(), t.name.as_str(), t.at_ms.unwrap_or(0)))
+                .collect();
             tx.execute(
                 "UPDATE pending_op SET sent_to = ?2 WHERE id = ?1",
-                params![id, serde_json::to_string(&targets)?],
+                params![id, serde_json::to_string(&json)?],
             )?;
         }
         tx.commit()?;
@@ -821,6 +897,24 @@ impl Db {
     /// The parent and name queued op `id` was sent under as a create, in the
     /// order it was ([`Db::note_create_target`]).
     pub fn create_targets(&self, id: i64) -> Result<Vec<(String, String)>> {
+        Ok(self
+            .sent_targets(id)?
+            .into_iter()
+            .map(|t| (t.parent, t.name))
+            .collect())
+    }
+
+    /// When queued create `id` was first sent, if that was recorded. Rows
+    /// written before the time was kept have none.
+    pub fn create_first_sent(&self, id: i64) -> Result<Option<i64>> {
+        Ok(self
+            .sent_targets(id)?
+            .into_iter()
+            .filter_map(|t| t.at_ms.filter(|&at| at > 0))
+            .min())
+    }
+
+    fn sent_targets(&self, id: i64) -> Result<Vec<SentTarget>> {
         let sent: Option<String> = self
             .conn
             .lock()
@@ -829,9 +923,7 @@ impl Db {
             })
             .optional()?
             .flatten();
-        Ok(sent
-            .and_then(|json| serde_json::from_str(&json).ok())
-            .unwrap_or_default())
+        Ok(parse_sent_to(sent.as_deref()).unwrap_or_default())
     }
 
     /// The SHA-1 of each blob queued op `id` sent as a create
@@ -879,6 +971,27 @@ impl Db {
         Ok(n > 0)
     }
 
+    /// Replace the sidecar of op `id`, but only while it still holds the blob
+    /// at `blob_path`.
+    ///
+    /// The drain fills an incomplete blob in place and then records it as
+    /// whole, so a retry after a lost answer can recognise its own bytes on the
+    /// server. A write that closed meanwhile has pointed the row at a newer
+    /// blob with its own sidecar; that one must not be overwritten. Returns
+    /// false when the row is gone or holds another blob.
+    pub fn update_op_meta_for_blob(
+        &self,
+        id: i64,
+        blob_path: &str,
+        meta_json: &str,
+    ) -> Result<bool> {
+        let n = self.conn.lock().execute(
+            "UPDATE pending_op SET meta_json = ?3 WHERE id = ?1 AND blob_path = ?2",
+            params![id, blob_path, meta_json],
+        )?;
+        Ok(n > 0)
+    }
+
     /// Point a queued create at a new parent and name, for a node renamed or
     /// moved before it ever reached the server.
     ///
@@ -892,7 +1005,7 @@ impl Db {
     /// name it no longer wants, such as one held by a queued change. A parked
     /// create stays parked.
     pub fn rewrite_op_target(&self, uid: &str, parent_uid: &str, name: &str) -> Result<bool> {
-        let conn = self.conn.lock();
+        let conn = self.durable()?;
         let lid = node_lid(&conn, uid)?;
         let parent_lid = node_lid(&conn, parent_uid)?;
         let n = conn.execute(
@@ -1127,15 +1240,9 @@ impl Db {
                 "SELECT id, kind, {UID_NOW}, {PARENT_NOW}, name, blob_path, meta_json, created_at,
                         attempts, last_error, next_attempt_at
                  FROM pending_op
-                 WHERE next_attempt_at <= ?1
-                   AND claimed_at = 0
-                   AND (parent_uid IS NULL OR substr({PARENT_NOW}, 1, {n}) <> '{v}~')
-                   AND uid NOT IN (SELECT uid FROM pending_op WHERE claimed_at <> 0)
-                   AND (lid IS NULL OR lid NOT IN (
-                     SELECT lid FROM pending_op WHERE claimed_at <> 0 AND lid IS NOT NULL))
+                 WHERE next_attempt_at <= ?1 AND {claimable}
                  ORDER BY id LIMIT 1",
-                v = LOCAL_VOLUME,
-                n = LOCAL_VOLUME.len() + 1,
+                claimable = claimable(),
             ))?;
             stmt.query_row(params![now], |r| {
                 Ok(PendingOp {
@@ -1208,19 +1315,17 @@ impl Db {
     /// debounced or backed-off op becomes eligible rather than waiting the full
     /// idle-poll interval.
     ///
-    /// Claimed ops are excluded: another worker is already on them, so they are
-    /// not work this one is waiting for, and counting them would have an idle
-    /// worker spin on a row it cannot have.
+    /// Only rows [`claim_next_due_op`](Self::claim_next_due_op) could take
+    /// count. A claimed op, or one held behind a claimed op on the same node,
+    /// is not work this worker is waiting for, and counting it would have an
+    /// idle worker spin on a row it cannot have.
     pub fn earliest_due_at(&self) -> Result<Option<i64>> {
         let conn = self.read();
         let ts: Option<i64> = conn
             .query_row(
                 &format!(
-                    "SELECT MIN(next_attempt_at) FROM pending_op \
-                     WHERE claimed_at = 0 \
-                       AND (parent_uid IS NULL OR substr({PARENT_NOW}, 1, {n}) <> '{v}~')",
-                    v = LOCAL_VOLUME,
-                    n = LOCAL_VOLUME.len() + 1,
+                    "SELECT MIN(next_attempt_at) FROM pending_op WHERE {claimable}",
+                    claimable = claimable(),
                 ),
                 [],
                 |r| r.get(0),
@@ -1378,12 +1483,26 @@ impl Db {
     }
 
     /// [`retry_op_now`](Self::retry_op_now) for every op that has failed at
-    /// least once. Returns how many rows changed.
+    /// least once, for the user's "Retry all". Returns how many rows changed.
     pub fn retry_failed_ops_now(&self, now: i64) -> Result<usize> {
+        self.retry_ops_now(now, "")
+    }
+
+    /// [`retry_failed_ops_now`](Self::retry_failed_ops_now) for the ops Drive
+    /// did not refuse, for a reconnect. A link coming back changes nothing
+    /// about a full quota or a missing permission, so those keep their backoff
+    /// instead of all being sent again at once.
+    pub fn retry_unrefused_ops_now(&self, now: i64) -> Result<usize> {
+        self.retry_ops_now(now, "AND issue IS NULL")
+    }
+
+    fn retry_ops_now(&self, now: i64, filter: &str) -> Result<usize> {
         let conn = self.conn.lock();
         let changed = conn.execute(
-            "UPDATE pending_op SET next_attempt_at = ?1
-             WHERE attempts > 0 AND next_attempt_at > ?1 AND next_attempt_at < ?2",
+            &format!(
+                "UPDATE pending_op SET next_attempt_at = ?1
+                 WHERE attempts > 0 AND next_attempt_at > ?1 AND next_attempt_at < ?2 {filter}"
+            ),
             params![now, PARK_UNTIL],
         )?;
         Ok(changed)

crates/pdfs-core/src/db/sync.rs

@@ -45,6 +45,12 @@ pub struct StoredSyncEntry {
     pub local_mtime_ns: Option<i64>,
     pub remote_rev: Option<String>,
     pub remote_hash: Option<String>,
+    /// The id of the remote revision this row was synced at. A mirror upload
+    /// checks it before it supersedes what Drive holds, because another client
+    /// may have committed a revision since (`docs/BUGS.md` B249). `None` on a
+    /// row written before schema 44, or by a pass that did not learn it; the
+    /// check then falls back to `remote_rev` and `remote_hash`.
+    pub remote_revision_id: Option<String>,
 }
 
 impl Db {
@@ -139,6 +145,17 @@ impl Db {
         Ok(())
     }
 
+    /// Re-point a synced folder at the share that now holds its remote folder,
+    /// after the folder moved to another device without changing its uid.
+    pub fn sync_folder_set_share(&self, id: i64, share_id: &str) -> Result<()> {
+        let conn = self.conn.lock();
+        conn.execute(
+            "UPDATE sync_folder SET remote_share_id = ?2 WHERE id = ?1",
+            params![id, share_id],
+        )?;
+        Ok(())
+    }
+
     /// Queue (or, with `None`, withdraw) a mode the folder should move to once it
     /// is safe to switch.
     pub fn sync_folder_set_pending_mode(&self, id: i64, mode: Option<&str>) -> Result<()> {
@@ -177,7 +194,7 @@ impl Db {
         let conn = self.read();
         let mut stmt = conn.prepare(
             "SELECT rel_path, remote_uid, local_mtime, local_size, remote_rev, remote_hash,
-                    local_mtime_ns
+                    local_mtime_ns, remote_revision_id
              FROM sync_entry WHERE folder_id = ?1",
         )?;
         let rows = stmt.query_map(params![folder_id], |r| {
@@ -189,6 +206,7 @@ impl Db {
                 remote_rev: r.get(4)?,
                 remote_hash: r.get(5)?,
                 local_mtime_ns: r.get(6)?,
+                remote_revision_id: r.get(7)?,
             })
         })?;
         let mut map = HashMap::new();
@@ -227,15 +245,16 @@ impl Db {
         conn.execute(
             "INSERT INTO sync_entry
                (folder_id, rel_path, remote_uid, local_mtime, local_size, remote_rev,
-                remote_hash, local_mtime_ns)
-             VALUES (?1, ?2, ?3, ?4, ?5, ?6, ?7, ?8)
+                remote_hash, local_mtime_ns, remote_revision_id)
+             VALUES (?1, ?2, ?3, ?4, ?5, ?6, ?7, ?8, ?9)
              ON CONFLICT(folder_id, rel_path) DO UPDATE SET
-               remote_uid     = excluded.remote_uid,
-               local_mtime    = excluded.local_mtime,
-               local_size     = excluded.local_size,
-               remote_rev     = excluded.remote_rev,
-               remote_hash    = excluded.remote_hash,
-               local_mtime_ns = excluded.local_mtime_ns",
+               remote_uid         = excluded.remote_uid,
+               local_mtime        = excluded.local_mtime,
+               local_size         = excluded.local_size,
+               remote_rev         = excluded.remote_rev,
+               remote_hash        = excluded.remote_hash,
+               local_mtime_ns     = excluded.local_mtime_ns,
+               remote_revision_id = excluded.remote_revision_id",
             params![
                 folder_id,
                 e.rel_path,
@@ -245,6 +264,7 @@ impl Db {
                 e.remote_rev,
                 e.remote_hash,
                 e.local_mtime_ns,
+                e.remote_revision_id,
             ],
         )?;
         Ok(())
@@ -295,7 +315,7 @@ impl Db {
         {
             let mut select = tx.prepare(
                 "SELECT rel_path, remote_uid, local_mtime, local_size, remote_rev, remote_hash,
-                        local_mtime_ns
+                        local_mtime_ns, remote_revision_id
                    FROM sync_entry
                   WHERE folder_id = ?1
                     AND (rel_path = ?2 OR substr(rel_path, 1, length(?2) + 1) = ?2 || '/')",
@@ -310,6 +330,7 @@ impl Db {
                         remote_rev: r.get(4)?,
                         remote_hash: r.get(5)?,
                         local_mtime_ns: r.get(6)?,
+                        remote_revision_id: r.get(7)?,
                     })
                 })?
                 .collect::<rusqlite::Result<Vec<_>>>()?;
@@ -321,8 +342,8 @@ impl Db {
             let mut insert = tx.prepare(
                 "INSERT OR REPLACE INTO sync_entry
                    (folder_id, rel_path, remote_uid, local_mtime, local_size, remote_rev,
-                    remote_hash, local_mtime_ns)
-                 VALUES (?1, ?2, ?3, ?4, ?5, ?6, ?7, ?8)",
+                    remote_hash, local_mtime_ns, remote_revision_id)
+                 VALUES (?1, ?2, ?3, ?4, ?5, ?6, ?7, ?8, ?9)",
             )?;
             for row in rows {
                 let rel = format!("{to_rel}{}", &row.rel_path[from_rel.len()..]);
@@ -335,6 +356,7 @@ impl Db {
                     row.remote_rev,
                     row.remote_hash,
                     row.local_mtime_ns,
+                    row.remote_revision_id,
                 ])?;
             }
         }

crates/pdfs-core/src/db/tests.rs

@@ -1283,6 +1283,90 @@ fn a_corrupt_database_is_moved_aside_and_rebuilt() {
     let _ = std::fs::remove_file(path.with_extension("db.lock"));
 }
 
+/// A rebuilt database must not lose what only this machine has: writes Drive
+/// has not received, the mirror baselines and the pins (`docs/BUGS.md` B216).
+#[test]
+fn a_rebuild_keeps_the_queue_baselines_and_pins_of_the_damaged_file() {
+    let id = now_test_id();
+    let damaged =
+        std::env::temp_dir().join(format!("pdfs-salvage-old-{}-{id}.db", std::process::id()));
+    let fresh =
+        std::env::temp_dir().join(format!("pdfs-salvage-new-{}-{id}.db", std::process::id()));
+
+    let db = Db::open(&damaged).unwrap();
+    db.upsert_node(&folder("root", None, "My Files")).unwrap();
+    db.upsert_node(&file("listed", "root", "listed.txt", 1))
+        .unwrap();
+    db.upsert_node(&file("queued", "root", "queued.txt", 2))
+        .unwrap();
+    db.set_listed(&uid("root"), true).unwrap();
+    db.enqueue_op(&PendingOp {
+        id: 0,
+        kind: OP_REVISION.to_string(),
+        uid: uid("queued").to_string(),
+        parent_uid: None,
+        name: None,
+        blob_path: Some("/staging/queued".into()),
+        meta_json: None,
+        created_at: 1,
+        attempts: 3,
+        last_error: None,
+        next_attempt_at: 0,
+    })
+    .unwrap();
+    let folder_id = db
+        .sync_folder_add("/home/me/Docs", "vol~docs", "share")
+        .unwrap();
+    db.sync_entry_upsert(
+        folder_id,
+        &StoredSyncEntry {
+            rel_path: "a.txt".into(),
+            remote_uid: Some("vol~a".into()),
+            local_mtime: 5,
+            local_mtime_ns: None,
+            local_size: 6,
+            remote_rev: Some("7".into()),
+            remote_hash: Some("8".into()),
+            remote_revision_id: None,
+        },
+    )
+    .unwrap();
+    db.pin_add("vol~pinned", "/pinned", true).unwrap();
+    drop(db);
+
+    let db = Db::open(&fresh).unwrap();
+    let results = salvage(&db.conn.lock(), &damaged);
+    assert!(results.iter().all(|(_, r)| r.is_ok()), "{results:?}");
+
+    let ops = db.pending_ops().unwrap();
+    assert_eq!(ops.len(), 1);
+    assert_eq!(ops[0].uid, uid("queued").to_string());
+    assert_eq!(ops[0].blob_path.as_deref(), Some("/staging/queued"));
+    // The op's node came with it; the rest of the tree is fetched again.
+    assert!(
+        db.node_by_uid(&uid("queued").to_string())
+            .unwrap()
+            .is_some()
+    );
+    assert!(
+        db.node_by_uid(&uid("listed").to_string())
+            .unwrap()
+            .is_none()
+    );
+    assert_eq!(db.sync_entries(folder_id).unwrap().len(), 1);
+    assert!(db.is_pinned("vol~pinned").unwrap());
+    drop(db);
+
+    for path in [&damaged, &fresh] {
+        for suffix in ["", "-wal", "-shm"] {
+            let mut file = path.as_os_str().to_owned();
+            file.push(suffix);
+            let _ = std::fs::remove_file(std::path::PathBuf::from(file));
+        }
+        let _ = std::fs::remove_file(path.with_extension("db.lock"));
+    }
+}
+
 fn local(path: &str, name: &str, is_dir: bool) -> LocalEntry {
     LocalEntry {
         path: path.into(),
@@ -1346,6 +1430,77 @@ fn rescanning_an_unchanged_file_keeps_exactly_one_index_entry() {
     }
 }
 
+/// A scan that stopped early or lost a batch did not see every file, so it
+/// must not prune the ones it missed (`docs/BUGS.md` B217).
+#[test]
+fn a_partial_local_scan_prunes_nothing() {
+    let db = Db::open_in_memory().unwrap();
+    let g = db.local_begin_scan().unwrap();
+    db.local_upsert_batch(
+        g,
+        &[
+            local("/home/u/a.txt", "a.txt", false),
+            local("/home/u/b.txt", "b.txt", false),
+        ],
+    )
+    .unwrap();
+    assert_eq!(db.local_finish_scan(g, 1).unwrap(), 2);
+
+    let g = db.local_begin_scan().unwrap();
+    db.local_upsert_batch(g, &[local("/home/u/a.txt", "a.txt", false)])
+        .unwrap();
+    assert_eq!(db.local_finish_partial_scan(2).unwrap(), 2);
+    assert_eq!(db.search_local("b.txt", 10).unwrap().len(), 1);
+    assert_eq!(db.local_indexed_at().unwrap(), Some(2));
+}
+
+/// Deleted entries pile up in an FTS5 index until it is compacted. The daily
+/// compaction must leave both indexes whole and searchable, and must not run
+/// again the same day (`docs/BUGS.md` B217).
+#[test]
+fn compacting_the_search_indexes_keeps_them_whole_and_runs_once_a_day() {
+    let db = Db::open_in_memory().unwrap();
+    db.upsert_node(&folder("root", None, "My Files")).unwrap();
+    db.upsert_node(&file("f1", "root", "quarterly-report.pdf", 1))
+        .unwrap();
+    for round in 0..20 {
+        let g = db.local_begin_scan().unwrap();
+        let name = format!("churn-{round}.txt");
+        db.local_upsert_batch(
+            g,
+            &[
+                local("/home/u/keep.txt", "keep.txt", false),
+                local(&format!("/home/u/{name}"), &name, false),
+            ],
+        )
+        .unwrap();
+        // Far in the past, so no scan compacts on its own.
+        db.local_finish_scan(g, 0).unwrap();
+    }
+
+    let day = 24 * 60 * 60;
+    db.compact_search_indexes_if_due(day).unwrap();
+    {
+        let conn = db.conn.lock();
+        for table in ["local_fts", "nodes_fts"] {
+            conn.execute(
+                &format!("INSERT INTO {table}({table}) VALUES('integrity-check')"),
+                [],
+            )
+            .unwrap();
+        }
+    }
+    assert_eq!(db.search_local("keep", 10).unwrap().len(), 1);
+    assert_eq!(db.search_local("churn-19", 10).unwrap().len(), 1);
+    assert!(db.search_local("churn-3.txt", 10).unwrap().is_empty());
+    assert_eq!(db.search("quarterly", 10).unwrap().len(), 1);
+    let stamp = |db: &Db| db.state_str("fts_compacted_at").unwrap();
+    assert_eq!(stamp(&db).as_deref(), Some(day.to_string().as_str()));
+
+    db.compact_search_indexes_if_due(day + 60).unwrap();
+    assert_eq!(stamp(&db).as_deref(), Some(day.to_string().as_str()));
+}
+
 /// Queries below the trigram minimum still match, via the `LIKE` fallback.
 #[test]
 fn local_search_short_query_like_fallback() {
@@ -1689,9 +1844,16 @@ fn writing_nodes_does_not_scale_with_the_size_of_the_index() {
             .collect();
         db.upsert_nodes(&batch).unwrap();
 
-        let t = Instant::now();
-        db.upsert_nodes(&batch).unwrap();
-        t.elapsed()
+        // The fastest of a few runs: the rest of the suite runs alongside, and
+        // one run that lost the CPU to it read as the regression.
+        (0..5)
+            .map(|_| {
+                let t = Instant::now();
+                db.upsert_nodes(&batch).unwrap();
+                t.elapsed()
+            })
+            .min()
+            .unwrap()
     }
 
     let small = cost_against_index_of(200);
@@ -2191,6 +2353,100 @@ fn refuses_a_schema_newer_than_the_running_build() {
     let _ = std::fs::remove_file(path);
 }
 
+/// Queueing a write syncs it to disk, and leaves the writer at NORMAL after.
+///
+/// The op row is what makes a staged blob reachable once `close()` has
+/// reported success, so its commit must survive a power loss. Everything else
+/// the writer commits is metadata the next listing re-fetches, and pays only
+/// NORMAL's cost.
+#[test]
+fn queueing_a_write_commits_at_full_sync_and_restores_normal() {
+    let path = std::env::temp_dir().join(format!("pdfs-db-sync-{}.db", std::process::id()));
+    let _ = std::fs::remove_file(&path);
+    let db = Db::open(&path).unwrap();
+    let level = |db: &Db| -> i64 {
+        db.conn
+            .lock()
+            .query_row("PRAGMA synchronous", [], |r| r.get(0))
+            .unwrap()
+    };
+    // 1 = NORMAL, 2 = FULL.
+    assert_eq!(level(&db), 1);
+    {
+        let durable = db.durable().unwrap();
+        let during: i64 = durable
+            .query_row("PRAGMA synchronous", [], |r| r.get(0))
+            .unwrap();
+        assert_eq!(during, 2);
+    }
+    assert_eq!(level(&db), 1);
+
+    db.enqueue_op(&PendingOp {
+        id: 0,
+        kind: OP_TRASH.to_string(),
+        uid: uid("a").to_string(),
+        parent_uid: None,
+        name: Some("a".to_string()),
+        blob_path: None,
+        meta_json: None,
+        created_at: 1,
+        attempts: 0,
+        last_error: None,
+        next_attempt_at: 0,
+    })
+    .unwrap();
+    assert_eq!(level(&db), 1);
+    assert_eq!(db.pending_ops().unwrap().len(), 1);
+    drop(db);
+    for suffix in ["", "-wal", "-shm"] {
+        let _ = std::fs::remove_file(format!("{}{suffix}", path.display()));
+    }
+}
+
+/// A gap-filled blob is recorded as whole only while the op still holds it.
+///
+/// A write that closes during the drain points the row at a newer blob with
+/// its own sidecar. Overwriting that sidecar with the older blob's would
+/// describe bytes the row no longer holds.
+#[test]
+fn marking_a_blob_whole_leaves_a_newer_blob_alone() {
+    let db = Db::open_in_memory().unwrap();
+    let op = PendingOp {
+        id: 0,
+        kind: OP_REVISION.to_string(),
+        uid: uid("a").to_string(),
+        parent_uid: None,
+        name: None,
+        blob_path: Some("/staging/first".to_string()),
+        meta_json: Some(r#"{"complete":false}"#.to_string()),
+        created_at: 1,
+        attempts: 0,
+        last_error: None,
+        next_attempt_at: 0,
+    };
+    db.enqueue_op(&op).unwrap();
+    let id = db.pending_ops().unwrap()[0].id;
+
+    assert!(
+        db.update_op_meta_for_blob(id, "/staging/first", r#"{"complete":true}"#)
+            .unwrap()
+    );
+    assert_eq!(
+        db.pending_ops().unwrap()[0].meta_json.as_deref(),
+        Some(r#"{"complete":true}"#)
+    );
+
+    assert!(
+        !db.update_op_meta_for_blob(id, "/staging/older", r#"{"stale":true}"#)
+            .unwrap(),
+        "the row holds another blob"
+    );
+    assert_eq!(
+        db.pending_ops().unwrap()[0].meta_json.as_deref(),
+        Some(r#"{"complete":true}"#)
+    );
+}
+
 /// A queued write whose baseline is restamped must keep everything else.
 ///
 /// The restamp happens after our *own* upload seals a new revision under a
@@ -3920,15 +4176,15 @@ fn what_a_create_sent_outlives_a_newer_blob_its_trash_and_a_restart() {
             .unwrap();
         assert!(db.create_sent(id).unwrap().is_empty());
         assert!(db.create_targets(id).unwrap().is_empty());
-        db.note_create_target(id, &parent, "c").unwrap();
-        db.note_create_target(id, &parent, "c").unwrap();
+        db.note_create_target(id, &parent, "c", 10).unwrap();
+        db.note_create_target(id, &parent, "c", 20).unwrap();
         db.note_create_sent(id, "aaaa").unwrap();
         db.note_create_sent(id, "aaaa").unwrap();
         db.record_op_failure(id, "no answer", 0).unwrap();
         db.attach_blob_to_create("local~sent", "/staging/second", "{}")
             .unwrap()
             .expect("the create is still queued");
-        db.note_create_target(id, &parent, "d").unwrap();
+        db.note_create_target(id, &parent, "d", 30).unwrap();
         db.note_create_sent(id, "bbbb").unwrap();
         db.record_op_failure(id, "no answer", 0).unwrap();
         db.delete_ops_for_uid("local~sent").unwrap();
@@ -3951,6 +4207,73 @@ fn what_a_create_sent_outlives_a_newer_blob_its_trash_and_a_restart() {
     let _ = std::fs::remove_file(path);
 }
 
+/// A queued create knows when it first went out, which is where the window
+/// for adopting a node its lost answer left starts. Records written before
+/// the time was kept still list their targets, and one that does not parse is
+/// not replaced by the next target.
+#[test]
+fn a_create_remembers_when_it_was_first_sent() {
+    let db = Db::open_in_memory().unwrap();
+    let parent = uid("parent").to_string();
+    let (id, _) = db
+        .enqueue_op(&PendingOp {
+            id: 0,
+            kind: OP_CREATE.to_string(),
+            uid: "local~first".to_string(),
+            parent_uid: Some(parent.clone()),
+            name: Some("a.txt".to_string()),
+            blob_path: None,
+            meta_json: None,
+            created_at: 1,
+            attempts: 0,
+            last_error: None,
+            next_attempt_at: 0,
+        })
+        .unwrap();
+    assert_eq!(db.create_first_sent(id).unwrap(), None, "never sent");
+    db.note_create_target(id, &parent, "a.txt", 500).unwrap();
+    db.note_create_target(id, &parent, "a.txt", 900).unwrap();
+    db.note_create_target(id, &parent, "b.txt", 700).unwrap();
+    assert_eq!(db.create_first_sent(id).unwrap(), Some(500));
+
+    let set = |json: &str| {
+        db.conn
+            .lock()
+            .execute(
+                "UPDATE pending_op SET sent_to = ?2 WHERE id = ?1",
+                rusqlite::params![id, json],
+            )
+            .unwrap();
+    };
+    set(&format!(r#"[["{parent}","old.txt"]]"#));
+    assert_eq!(
+        db.create_targets(id).unwrap(),
+        vec![(parent.clone(), "old.txt".to_string())]
+    );
+    assert_eq!(db.create_first_sent(id).unwrap(), None);
+    db.note_create_target(id, &parent, "a.txt", 900).unwrap();
+    assert_eq!(
+        db.create_targets(id).unwrap().len(),
+        2,
+        "the old target stays"
+    );
+    assert_eq!(db.create_first_sent(id).unwrap(), Some(900));
+
+    set("not json");
+    db.note_create_target(id, &parent, "c.txt", 1000).unwrap();
+    let raw: String = db
+        .conn
+        .lock()
+        .query_row("SELECT sent_to FROM pending_op WHERE id = ?1", [id], |r| {
+            r.get(0)
+        })
+        .unwrap();
+    assert_eq!(
+        raw, "not json",
+        "an unreadable record is kept, not replaced"
+    );
+}
+
 /// A write after a create failed clears its attempts, so the next try goes
 /// out at once. The create was still sent: deleting the file then left no
 /// trash, and the file a lost answer made stayed on Drive under the name it
@@ -3974,7 +4297,7 @@ fn a_create_rewritten_after_it_failed_still_leaves_a_trash_when_deleted() {
             next_attempt_at: 0,
         })
         .unwrap();
-    db.note_create_target(id, &parent, "a.txt").unwrap();
+    db.note_create_target(id, &parent, "a.txt", 10).unwrap();
     db.note_create_sent(id, "aaaa").unwrap();
     db.record_op_failure(id, "no answer", 0).unwrap();
     db.attach_blob_to_create("local~sent", "/staging/second", "{}")
@@ -4940,6 +5263,28 @@ fn pending_mode_is_queued_until_the_mode_is_reached() {
     assert_eq!(folder.pending_mode, None);
 }
 
+#[test]
+fn moved_sync_folder_points_at_its_new_share() {
+    let db = Db::open_in_memory().unwrap();
+    let id = db
+        .sync_folder_add("/tmp/pdfs-moved-share", "vol~folder", "windows-share")
+        .unwrap();
+    let other = db
+        .sync_folder_add("/tmp/pdfs-unmoved-share", "vol~other", "windows-share")
+        .unwrap();
+
+    db.sync_folder_set_share(id, "linux-share").unwrap();
+
+    let folder = db.sync_folder_get(id).unwrap().unwrap();
+    assert_eq!(folder.remote_share_id, "linux-share");
+    // A move keeps the uid, so nothing but the share changes.
+    assert_eq!(folder.remote_uid, "vol~folder");
+    assert_eq!(
+        db.sync_folder_get(other).unwrap().unwrap().remote_share_id,
+        "windows-share"
+    );
+}
+
 #[test]
 fn mode_commit_clears_only_the_intent_it_satisfies() {
     let db = Db::open_in_memory().unwrap();
@@ -4999,6 +5344,7 @@ fn baseline_row(rel: &str) -> StoredSyncEntry {
         local_size: 7,
         remote_rev: Some("1700000000".into()),
         remote_hash: Some("7".into()),
+        remote_revision_id: None,
     }
 }
 
@@ -5093,6 +5439,7 @@ fn mirror_uid_lookup_covers_the_root_and_synced_descendants_only() {
             local_size: 2,
             remote_rev: Some("3".into()),
             remote_hash: Some("2".into()),
+            remote_revision_id: None,
             local_mtime_ns: None,
         },
     )
@@ -5110,6 +5457,7 @@ fn mirror_uid_lookup_covers_the_root_and_synced_descendants_only() {
             local_size: 2,
             remote_rev: Some("3".into()),
             remote_hash: Some("2".into()),
+            remote_revision_id: None,
             local_mtime_ns: None,
         },
     )
@@ -6287,6 +6635,71 @@ fn migration_v27_adds_the_access_deferral_column_to_a_v26_queue() {
     let _ = std::fs::remove_file(format!("{}.lock", path.display()));
 }
 
+/// V44 adds the remote revision a baseline row was synced at. A row carried
+/// over from V43 has none, and the mirror then compares the modification time
+/// and size as before, so upgrading changes nothing about what is in step
+/// (`docs/BUGS.md` B249).
+#[test]
+fn migration_v44_adds_the_synced_revision_without_disturbing_a_v43_baseline() {
+    let path = std::env::temp_dir().join(format!(
+        "pdfs-db-v43-fixture-{}-{}.db",
+        std::process::id(),
+        std::time::SystemTime::now()
+            .duration_since(std::time::UNIX_EPOCH)
+            .unwrap()
+            .as_nanos()
+    ));
+    let row = StoredSyncEntry {
+        rel_path: "notes.txt".into(),
+        remote_uid: Some("vol~notes".into()),
+        local_mtime: 1_700_000_000,
+        local_mtime_ns: Some(1_700_000_000_123_456_789),
+        local_size: 42,
+        remote_rev: Some("1700000000".into()),
+        remote_hash: Some("42".into()),
+        remote_revision_id: Some("rev-1".into()),
+    };
+    {
+        let db = Db::open(&path).unwrap();
+        let folder = db
+            .sync_folder_add("/home/me/Mirror", "vol~root", "share")
+            .unwrap();
+        db.sync_entry_upsert(folder, &row).unwrap();
+    }
+    {
+        // Put the file back in the state a released V43 database was in.
+        let conn = rusqlite::Connection::open(&path).unwrap();
+        conn.execute_batch(
+            "ALTER TABLE sync_entry DROP COLUMN remote_revision_id;
+             UPDATE sync_state SET value = '43' WHERE key = 'schema_version';",
+        )
+        .unwrap();
+    }
+
+    let db = Db::open(&path).unwrap();
+    let entries = db.sync_entries(1).unwrap();
+    let entry = entries.get("notes.txt").expect("the baseline row survives");
+    assert_eq!(
+        entry,
+        &StoredSyncEntry {
+            remote_revision_id: None,
+            ..row.clone()
+        }
+    );
+
+    // And the column is live, including through a move of the row.
+    db.sync_entry_upsert(1, &row).unwrap();
+    db.sync_entries_move(1, "notes.txt", 1, "moved.txt")
+        .unwrap();
+    let entries = db.sync_entries(1).unwrap();
+    assert_eq!(
+        entries["moved.txt"].remote_revision_id.as_deref(),
+        Some("rev-1")
+    );
+    drop(db);
+    let _ = std::fs::remove_file(&path);
+}
+
 /// A mirror baseline carried over from V27 keeps its rows, and each one reads
 /// back with no nanosecond time. That `None` is the whole point: it makes the
 /// comparison fall back to whole seconds for rows written before the column
@@ -6317,6 +6730,7 @@ fn migration_v28_adds_sub_second_local_times_without_disturbing_a_v27_baseline()
                 local_size: 42,
                 remote_rev: Some("1700000000".into()),
                 remote_hash: Some("42".into()),
+                remote_revision_id: None,
             },
         )
         .unwrap();
@@ -6525,6 +6939,36 @@ fn an_idle_worker_does_not_wait_on_an_op_another_worker_has() {
     );
 }
 
+/// B200: a rename queued behind a long upload of the same node is due, but no
+/// worker may claim it until the upload retires. Counted as due, it had every
+/// idle worker wake at once, find nothing, and go round again.
+#[test]
+fn earliest_due_at_skips_an_op_held_behind_a_claimed_one() {
+    let db = Db::open_in_memory().unwrap();
+    let root = uid("root").to_string();
+    let mut revision = bulk_op(0, &root);
+    revision.parent_uid = None;
+    db.enqueue_op(&revision).unwrap();
+    db.enqueue_op(&PendingOp {
+        kind: OP_RENAME.to_string(),
+        parent_uid: Some(root.clone()),
+        blob_path: None,
+        meta_json: None,
+        ..bulk_op(0, &root)
+    })
+    .unwrap();
+
+    db.claim_next_due_op(10)
+        .unwrap()
+        .expect("the revision is due");
+    assert!(db.claim_next_due_op(10).unwrap().is_none());
+    assert_eq!(
+        db.earliest_due_at().unwrap(),
+        None,
+        "a row no worker can claim is not work an idle worker is waiting for"
+    );
+}
+
 /// Trashing a photo from the gallery must not leave it behind on an album page:
 /// the row goes, its album membership goes with it, and nothing else moves.
 #[test]
@@ -7157,6 +7601,56 @@ fn a_refused_change_names_its_node_by_local_id() {
     );
 }
 
+/// The name checks the drain makes before each op look the name up in an
+/// index. Scanning the queue instead made a large offline batch quadratic.
+#[test]
+fn queue_name_checks_use_an_index() {
+    let db = Db::open_in_memory().unwrap();
+    let conn = db.conn.lock();
+    let plan = |sql: &str| -> String {
+        let mut stmt = conn.prepare(&format!("EXPLAIN QUERY PLAN {sql}")).unwrap();
+        stmt.query_map([], |r| r.get::<_, String>(3))
+            .unwrap()
+            .map(|row| row.unwrap())
+            .collect::<Vec<_>>()
+            .join("; ")
+    };
+    for sql in [
+        "SELECT 1 FROM pending_op WHERE kind = 'trash' AND name = 'a'",
+        "SELECT 1 FROM pending_op WHERE name = 'a' AND kind IN ('create', 'mkdir', 'rename')",
+        "SELECT 1 FROM pending_op WHERE kind = 'rename'",
+    ] {
+        let plan = plan(sql);
+        assert!(plan.contains("pending_op_kind_name"), "{sql}: {plan}");
+    }
+}
+
+/// A reconnect moves up the ops that failed for want of a link. One Drive
+/// refused, for quota or access, keeps its backoff: the link coming back
+/// changes nothing about it. "Retry all" still moves both.
+#[test]
+fn a_reconnect_leaves_refused_ops_to_their_backoff() {
+    let db = Db::open_in_memory().unwrap();
+    let offline = queued_op(&db, "vol~a", 2, 90_000);
+    let refused = queued_op(&db, "vol~b", 2, 90_000);
+    db.set_op_issue(refused, Some("quota")).unwrap();
+
+    assert_eq!(db.retry_unrefused_ops_now(5_000).unwrap(), 1);
+    let due = |id: i64| {
+        db.pending_ops()
+            .unwrap()
+            .into_iter()
+            .find(|op| op.id == id)
+            .unwrap()
+            .next_attempt_at
+    };
+    assert_eq!(due(offline), 5_000);
+    assert_eq!(due(refused), 90_000);
+
+    assert_eq!(db.retry_failed_ops_now(5_000).unwrap(), 1);
+    assert_eq!(due(refused), 5_000);
+}
+
 #[test]
 fn retry_all_touches_only_ops_that_have_failed() {
     let db = Db::open_in_memory().unwrap();

crates/pdfs-core/src/error.rs

@@ -32,6 +32,16 @@ pub enum Error {
     #[error("saved session can no longer unlock your keys — run `pdfs login` again")]
     ReloginRequired,
 
+    /// The account has a separate mailbox password that has not been entered
+    /// since login, so its keys cannot be unlocked. The fix is
+    /// [`auth::unlock`](crate::auth::unlock), not a new login.
+    #[error("account is locked — enter the mailbox password with `pdfs unlock`")]
+    Locked,
+
+    /// The mailbox password was checked against the account and is wrong.
+    #[error("that mailbox password does not unlock your account")]
+    WrongMailboxPassword,
+
     /// The login was gated behind human verification. Not a failure the user can
     /// fix by retrying: the challenge has to be solved and the login restarted
     /// with the resulting token (see [`auth::login_verified`](crate::auth::login_verified)).
@@ -144,19 +154,20 @@ impl CoreError {
     /// through the boxes the drain deals in, where the concrete type survives
     /// but the static one does not.
     ///
-    /// A failure that is not an API response at all — a transport error, a
-    /// timeout, a TLS failure — is what being offline looks like from here, so
-    /// it classifies as [`ErrorKind::Offline`] rather than
-    /// [`ErrorKind::Remote`]: the request never reached Proton, and telling the
-    /// user their connection is down beats telling them the server refused.
+    /// A transport error, a timeout or a TLS failure is what being offline
+    /// looks like from here, so it classifies as [`ErrorKind::Offline`] rather
+    /// than [`ErrorKind::Remote`]: the request never reached Proton, and
+    /// telling the user their connection is down beats telling them the
+    /// server refused. The SDK's other failures say what went wrong instead
+    /// (see [`proton_kind`]).
+    ///
+    /// Callers also hand it this crate's [`Error`] from the cache and the
+    /// database, which is not a transport error at all. Taking those for
+    /// "offline" told the user their connection was down when a pin failed on
+    /// the database (`docs/BUGS.md` B266), so the source chain is searched for
+    /// either type before falling back.
     pub fn from_api(e: &(dyn std::error::Error + 'static), what: &str) -> Self {
-        let kind = match e.downcast_ref::<proton_sdk::ProtonError>() {
-            Some(proton_sdk::ProtonError::Api(api)) => api_kind(api.code),
-            // A `ProtonError` that is not an `Api` variant never reached the
-            // API; so does anything that is not a `ProtonError` at all.
-            _ => ErrorKind::Offline,
-        };
-        Self::new(kind, format!("{what}: {e}"))
+        Self::new(api_kind_of(e), format!("{what}: {e}"))
     }
 
     /// Prefix the message while keeping the classification.
@@ -198,16 +209,57 @@ impl From<serde_json::Error> for CoreError {
 
 impl From<Error> for CoreError {
     fn from(e: Error) -> Self {
-        let kind = match &e {
-            Error::NotLoggedIn | Error::ReloginRequired | Error::HumanVerificationRequired(_) => {
-                ErrorKind::Denied
-            }
-            Error::Proton(proton_sdk::ProtonError::Api(api)) => api_kind(api.code),
-            // A `ProtonError` that never reached the API is a transport failure.
-            Error::Proton(_) => ErrorKind::Offline,
-            _ => ErrorKind::Internal,
-        };
-        Self::new(kind, e.to_string())
+        Self::new(core_kind(&e), e.to_string())
+    }
+}
+
+/// What this crate's [`Error`] means to a front-end.
+fn core_kind(e: &Error) -> ErrorKind {
+    match e {
+        Error::NotLoggedIn
+        | Error::ReloginRequired
+        | Error::Locked
+        | Error::WrongMailboxPassword
+        | Error::HumanVerificationRequired(_) => ErrorKind::Denied,
+        Error::Proton(proton) => proton_kind(proton),
+        _ => ErrorKind::Internal,
+    }
+}
+
+/// The kind for [`CoreError::from_api`]: the first SDK or crate error in `e`'s
+/// source chain decides it.
+fn api_kind_of(e: &(dyn std::error::Error + 'static)) -> ErrorKind {
+    let mut cause = Some(e);
+    while let Some(err) = cause {
+        if let Some(proton) = err.downcast_ref::<proton_sdk::ProtonError>() {
+            return proton_kind(proton);
+        }
+        if let Some(core) = err.downcast_ref::<Error>() {
+            return core_kind(core);
+        }
+        cause = err.source();
+    }
+    // Not the SDK's at all: a timeout around the call, or the socket.
+    ErrorKind::Offline
+}
+
+/// What a failed SDK call means to a front-end.
+///
+/// Only a transport failure is the connection. The rest happened on this
+/// machine, and calling them "offline" sent the user to check a network that
+/// worked (issue #38: a photo upload on an account without a photo library
+/// read "You're offline").
+fn proton_kind(e: &proton_sdk::ProtonError) -> ErrorKind {
+    use proton_sdk::ProtonError as P;
+    match e {
+        P::Api(api) => api_kind(api.code),
+        P::Transport(_) => ErrorKind::Offline,
+        // Proton answered, but not with anything this client can read.
+        P::Serialization(_) => ErrorKind::Remote,
+        // The SDK refused the call before sending it, such as an upload to a
+        // photo library the account does not have.
+        P::InvalidOperation(_) => ErrorKind::Invalid,
+        P::Crypto(_) | P::KeysLocked => ErrorKind::Internal,
     }
 }
 
@@ -266,6 +318,32 @@ fn api_kind(code: proton_sdk::api::ResponseCode) -> ErrorKind {
     }
 }
 
+/// Whether `e` says the session itself is gone: its refresh token was refused,
+/// or the account was deleted or disabled.
+///
+/// Nothing but a new login helps then, and no retry will ever succeed, so a
+/// caller must not take it for a lost connection and wait for it to come back
+/// (issue #35: a revoked session was shown as "offline" for good).
+pub fn session_revoked(e: &proton_sdk::ProtonError) -> bool {
+    use proton_sdk::api::ResponseCode as C;
+    match e {
+        proton_sdk::ProtonError::Api(api) => {
+            api.is_invalid_refresh_token()
+                || matches!(api.code, C::AccountDeleted | C::AccountDisabled)
+        }
+        _ => false,
+    }
+}
+
+/// Whether `e` is Proton's temporary block on a sign-in (code 2028).
+///
+/// Its message says the app version is no longer supported, which is not what
+/// happened: the release is current and only waiting helps (issues #28, #39).
+/// A front-end must say that instead of passing the message through.
+pub fn sign_in_blocked(e: &proton_sdk::ProtonError) -> bool {
+    matches!(e, proton_sdk::ProtonError::Api(api) if api.code == proton_sdk::api::ResponseCode::Blocked)
+}
+
 /// The result every request-serving method in the daemon returns.
 pub type CoreResult<T> = std::result::Result<T, CoreError>;
 
@@ -297,6 +375,25 @@ mod tests {
         assert_eq!(api_kind(C::ProtonDriveUnknown), ErrorKind::Remote);
     }
 
+    #[test]
+    fn only_a_refused_refresh_or_a_closed_account_revokes_the_session() {
+        assert!(session_revoked(&api(C::InvalidRefreshToken)));
+        assert!(session_revoked(&api(C::AccountDeleted)));
+        assert!(session_revoked(&api(C::AccountDisabled)));
+        // One file the account may not touch says nothing about the session.
+        assert!(!session_revoked(&api(C::Forbidden)));
+        assert!(!session_revoked(&api(C::Timeout)));
+        assert!(!session_revoked(&ProtonError::KeysLocked));
+    }
+
+    #[test]
+    fn only_code_2028_is_a_blocked_sign_in() {
+        assert!(sign_in_blocked(&api(C::Blocked)));
+        assert!(!sign_in_blocked(&api(C::OutdatedApp)));
+        assert!(!sign_in_blocked(&api(C::TooManyRequests)));
+        assert!(!sign_in_blocked(&ProtonError::KeysLocked));
+    }
+
     /// The regression this whole pass exists to prevent: before it, every SDK
     /// failure was hardcoded to `Remote`, so a 403 asked the user to retry a
     /// request that could never succeed.
@@ -327,6 +424,32 @@ mod tests {
         assert_eq!(CoreError::from_api(&io, "list").kind, ErrorKind::Offline);
     }
 
+    /// Issue #38: the SDK refused a photo upload before sending it, and the
+    /// app said "You're offline" while every other call went through.
+    #[test]
+    fn a_call_the_sdk_refuses_to_send_is_not_offline() {
+        let refused = ProtonError::invalid_operation("account has no photos volume");
+        let e = CoreError::from_api(&refused, "upload photo failed");
+        assert_eq!(e.kind, ErrorKind::Invalid);
+        assert!(e.message.ends_with("account has no photos volume"));
+        let e: CoreError = Error::Proton(ProtonError::KeysLocked).into();
+        assert_ne!(e.kind, ErrorKind::Offline);
+    }
+
+    /// A pin or a search that fails on the database is not the connection, so
+    /// it must not say "You're offline" (`docs/BUGS.md` B266). An SDK error
+    /// wrapped in this crate's type classifies as the SDK error does.
+    #[test]
+    fn a_database_error_handed_to_from_api_is_not_offline() {
+        let db = Error::Other("database is locked".into());
+        assert_eq!(CoreError::from_api(&db, "pin").kind, ErrorKind::Internal);
+        let wrapped = Error::Proton(api(C::DoesNotExist));
+        assert_eq!(
+            CoreError::from_api(&wrapped, "load node").kind,
+            ErrorKind::NotFound
+        );
+    }
+
     /// `Error` is the plumbing type; converting it must classify as sharply as
     /// the direct path, or the two disagree about the same failure.
     #[test]

crates/pdfs-core/src/exiftime.rs

@@ -0,0 +1,133 @@
+//! When a photo was taken, as its own EXIF tags say.
+//!
+//! The fallback for a photo nothing else dates: a Takeout photo without a
+//! sidecar or a date in its name, and a photo uploaded from the app. Without
+//! it the first was filed under the moment of the import and the second under
+//! the file's modification time, which a copy resets.
+
+use std::io::{BufRead, Seek};
+use std::path::Path;
+
+use crate::takeout::days_from_civil;
+
+/// The capture time in the EXIF of the file at `path`, in epoch seconds.
+pub fn capture_time_of(path: &Path) -> Option<i64> {
+    let file = std::fs::File::open(path).ok()?;
+    capture_time(&mut std::io::BufReader::new(file))
+}
+
+/// The capture time in the EXIF `reader` holds: `DateTimeOriginal`, then
+/// `DateTimeDigitized`, each adjusted by its `OffsetTime…` tag when the camera
+/// wrote one. Without an offset the time is read as UTC, as a date in a file
+/// name is (`takeout::capture_time_from_name`).
+pub fn capture_time(reader: &mut (impl BufRead + Seek)) -> Option<i64> {
+    let exif = exif::Reader::new().read_from_container(reader).ok()?;
+    let ascii = |tag: exif::Tag| -> Option<String> {
+        let field = exif.get_field(tag, exif::In::PRIMARY)?;
+        match &field.value {
+            exif::Value::Ascii(parts) => parts.first().map(|part| {
+                String::from_utf8_lossy(part)
+                    .trim_matches('\0')
+                    .trim()
+                    .to_string()
+            }),
+            _ => None,
+        }
+    };
+    [
+        (exif::Tag::DateTimeOriginal, exif::Tag::OffsetTimeOriginal),
+        (exif::Tag::DateTimeDigitized, exif::Tag::OffsetTimeDigitized),
+    ]
+    .into_iter()
+    .find_map(|(time, offset)| {
+        let local = parse_exif_time(&ascii(time)?)?;
+        let offset = ascii(offset).and_then(|o| parse_offset(&o)).unwrap_or(0);
+        Some(local - offset)
+    })
+}
+
+/// `YYYY:MM:DD HH:MM:SS` as epoch seconds, read as UTC. `None` for the
+/// all-zero or blank value cameras write when they do not know.
+fn parse_exif_time(text: &str) -> Option<i64> {
+    let bytes = text.as_bytes();
+    if bytes.len() < 19 || bytes[4] != b':' || bytes[7] != b':' || bytes[13] != b':' {
+        return None;
+    }
+    let number = |range: std::ops::Range<usize>| text.get(range)?.parse::<i64>().ok();
+    let (year, month, day) = (number(0..4)?, number(5..7)?, number(8..10)?);
+    let (hour, minute, second) = (number(11..13)?, number(14..16)?, number(17..19)?);
+    if !(1800..=9999).contains(&year)
+        || !(1..=12).contains(&month)
+        || !(1..=31).contains(&day)
+        || hour > 23
+        || minute > 59
+        || second > 60
+    {
+        return None;
+    }
+    Some(days_from_civil(year, month, day) * 86_400 + hour * 3600 + minute * 60 + second)
+}
+
+/// `+HH:MM` or `-HH:MM` as seconds east of UTC.
+fn parse_offset(text: &str) -> Option<i64> {
+    let sign = match text.as_bytes().first()? {
+        b'+' => 1,
+        b'-' => -1,
+        _ => return None,
+    };
+    let (hours, minutes) = text.get(1..)?.split_once(':')?;
+    let (hours, minutes) = (hours.parse::<i64>().ok()?, minutes.parse::<i64>().ok()?);
+    (hours <= 14 && minutes < 60).then_some(sign * (hours * 3600 + minutes * 60))
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn an_exif_time_reads_as_utc_and_its_offset_moves_it() {
+        // 2023-06-01 12:00:00 UTC.
+        let noon = 1_685_620_800;
+        assert_eq!(parse_exif_time("2023:06:01 12:00:00"), Some(noon));
+        assert_eq!(parse_offset("+02:00"), Some(7200));
+        assert_eq!(parse_offset("-05:30"), Some(-19_800));
+        assert_eq!(
+            parse_exif_time("2023:06:01 14:00:00").map(|t| t - parse_offset("+02:00").unwrap()),
+            Some(noon)
+        );
+    }
+
+    #[test]
+    fn an_unknown_exif_time_is_no_time() {
+        assert_eq!(parse_exif_time("0000:00:00 00:00:00"), None);
+        assert_eq!(parse_exif_time("    :  :     :  :  "), None);
+        assert_eq!(parse_exif_time(""), None);
+        assert_eq!(parse_offset("02:00"), None);
+    }
+
+    #[test]
+    fn a_photo_is_dated_by_its_original_time_and_offset() {
+        let ascii = |tag, text: &str| exif::Field {
+            tag,
+            ifd_num: exif::In::PRIMARY,
+            value: exif::Value::Ascii(vec![text.as_bytes().to_vec()]),
+        };
+        let taken = ascii(exif::Tag::DateTimeOriginal, "2023:06:01 14:00:00");
+        let offset = ascii(exif::Tag::OffsetTimeOriginal, "+02:00");
+        let digitized = ascii(exif::Tag::DateTimeDigitized, "2024:01:01 00:00:00");
+        let mut writer = exif::experimental::Writer::new();
+        writer.push_field(&taken);
+        writer.push_field(&offset);
+        writer.push_field(&digitized);
+        let mut tiff = std::io::Cursor::new(Vec::new());
+        writer.write(&mut tiff, false).unwrap();
+        tiff.set_position(0);
+        assert_eq!(capture_time(&mut tiff), Some(1_685_620_800));
+    }
+
+    #[test]
+    fn a_file_without_exif_has_no_capture_time() {
+        let mut png = std::io::Cursor::new(b"\x89PNG\r\n\x1a\n".to_vec());
+        assert_eq!(capture_time(&mut png), None);
+    }
+}

crates/pdfs-core/src/kernelkey.rs

@@ -0,0 +1,233 @@
+//! A secret held in the Linux kernel keyring, for as long as the user is logged in.
+//!
+//! This is where the key passphrases of a two-password account live by default:
+//! the mailbox password is never stored, and the secrets derived from it are
+//! kept in kernel memory — not on disk, not in the Secret Service — and vanish
+//! when the user's last session ends or the machine reboots. Both the daemon and
+//! `pdfs unlock` reach the same entry because it hangs off the *user* keyring.
+//! It is also where session tokens wait while the Secret Service refuses them
+//! ([`UNSAVED_TOKENS`]), so they outlive the process that holds them.
+//!
+//! Kernel keys are not paged to swap, are invisible to other users, and are
+//! wiped by [`clear`] (`KEYCTL_REVOKE`), which makes them a better home than a
+//! process's heap. Processes of the same user can still read them, exactly as
+//! they could ptrace the daemon: this protects against disk, backup and other
+//! users, not against code already running as you.
+//!
+//! The keyring may be unavailable (a container, a kernel built without
+//! `CONFIG_KEYS`); every operation then reports it as an error and the caller
+//! falls back to asking again, never to storing the secret somewhere weaker.
+
+use std::io;
+
+use zeroize::Zeroizing;
+
+/// One secret in the user keyring, by its description. Descriptions are
+/// namespaced so they cannot collide with another program's keys.
+pub struct Key {
+    description: &'static [u8],
+}
+
+/// The account's key passphrases (see the module docs).
+#[cfg(not(test))]
+pub const PASSPHRASES: Key = Key {
+    description: b"pdfs:key-passphrases\0",
+};
+/// Tests must never touch a real unlock.
+#[cfg(test)]
+pub const PASSPHRASES: Key = Key {
+    description: b"pdfs:key-passphrases:test\0",
+};
+
+/// Session tokens the Secret Service refused to store, until it takes them.
+/// A refresh token held only in a process's memory dies with the process.
+#[cfg(not(test))]
+pub const UNSAVED_TOKENS: Key = Key {
+    description: b"pdfs:unsaved-tokens\0",
+};
+#[cfg(test)]
+pub const UNSAVED_TOKENS: Key = Key {
+    description: b"pdfs:unsaved-tokens:test\0",
+};
+
+const KEY_TYPE: &[u8] = b"user\0";
+
+const KEY_SPEC_USER_KEYRING: i32 = -4;
+const KEYCTL_REVOKE: libc::c_long = 3;
+const KEYCTL_SETPERM: libc::c_long = 5;
+const KEYCTL_SEARCH: libc::c_long = 10;
+const KEYCTL_READ: libc::c_long = 11;
+
+/// Possessor and owner may view, read, write, search, link and set attributes;
+/// group and others get nothing.
+///
+/// A new key's default grants the owner only *view*, and read access to the
+/// possessor. A process possesses the user keyring only when its session
+/// keyring links to it, which a systemd user service or a container does not
+/// guarantee — so with the default, the daemon could store a key it then
+/// cannot read back. The owner is the same user that could ptrace the daemon
+/// anyway, so granting it read access gives up nothing.
+const PERM_OWNER_AND_POSSESSOR: u32 = 0x3f3f_0000;
+
+fn last_error<T>() -> io::Result<T> {
+    Err(io::Error::last_os_error())
+}
+
+fn find(description: &[u8]) -> io::Result<Option<libc::c_long>> {
+    // SAFETY: both strings are NUL-terminated and outlive the call.
+    let id = unsafe {
+        libc::syscall(
+            libc::SYS_keyctl,
+            KEYCTL_SEARCH,
+            KEY_SPEC_USER_KEYRING,
+            KEY_TYPE.as_ptr(),
+            description.as_ptr(),
+            0,
+        )
+    };
+    if id >= 0 {
+        return Ok(Some(id));
+    }
+    let err = io::Error::last_os_error();
+    match err.raw_os_error() {
+        // ENOKEY: not stored. EKEYREVOKED/EKEYEXPIRED: stored once, now gone.
+        Some(libc::ENOKEY | libc::EKEYREVOKED | libc::EKEYEXPIRED) => Ok(None),
+        _ => Err(err),
+    }
+}
+
+/// Stop this process from being core-dumped or ptraced by an unprivileged
+/// process of the same user, so the secrets in its memory stay out of crash
+/// reports. Call once at start of a long-lived process that holds them.
+pub fn forbid_dumps() {
+    // SAFETY: `PR_SET_DUMPABLE` takes plain integers and only affects this process.
+    let rc = unsafe { libc::prctl(libc::PR_SET_DUMPABLE, 0, 0, 0, 0) };
+    if rc != 0 {
+        tracing::warn!(error = %io::Error::last_os_error(), "could not mark the process non-dumpable");
+    }
+}
+
+impl Key {
+    /// Store `secret`, replacing any earlier one.
+    pub fn store(&self, secret: &[u8]) -> io::Result<()> {
+        // SAFETY: strings are NUL-terminated; the payload pointer/length pair
+        // describes `secret`, which outlives the call.
+        let id = unsafe {
+            libc::syscall(
+                libc::SYS_add_key,
+                KEY_TYPE.as_ptr(),
+                self.description.as_ptr(),
+                secret.as_ptr(),
+                secret.len(),
+                KEY_SPEC_USER_KEYRING,
+            )
+        };
+        if id < 0 {
+            return last_error();
+        }
+        // SAFETY: plain integer arguments.
+        let rc = unsafe {
+            libc::syscall(
+                libc::SYS_keyctl,
+                KEYCTL_SETPERM,
+                id,
+                PERM_OWNER_AND_POSSESSOR,
+            )
+        };
+        if rc < 0 {
+            // A key whose permissions are unknown is not one to leave behind.
+            let err = io::Error::last_os_error();
+            let _ = self.clear();
+            return Err(err);
+        }
+        Ok(())
+    }
+
+    /// Read the stored secret, or `None` when there is none.
+    pub fn load(&self) -> io::Result<Option<Zeroizing<Vec<u8>>>> {
+        let Some(id) = find(self.description)? else {
+            return Ok(None);
+        };
+        // Size first, then read; retry if the key was replaced in between.
+        for _ in 0..3 {
+            // SAFETY: a null buffer asks the kernel only for the payload length.
+            let len = unsafe {
+                libc::syscall(
+                    libc::SYS_keyctl,
+                    KEYCTL_READ,
+                    id,
+                    std::ptr::null_mut::<u8>(),
+                    0usize,
+                )
+            };
+            if len < 0 {
+                return match io::Error::last_os_error().raw_os_error() {
+                    Some(libc::ENOKEY | libc::EKEYREVOKED | libc::EKEYEXPIRED) => Ok(None),
+                    _ => last_error(),
+                };
+            }
+            let mut buf = Zeroizing::new(vec![0u8; len as usize]);
+            // SAFETY: `buf` is `len` writable bytes.
+            let read = unsafe {
+                libc::syscall(
+                    libc::SYS_keyctl,
+                    KEYCTL_READ,
+                    id,
+                    buf.as_mut_ptr(),
+                    buf.len(),
+                )
+            };
+            if read < 0 {
+                return last_error();
+            }
+            if read as usize <= buf.len() {
+                buf.truncate(read as usize);
+                return Ok(Some(buf));
+            }
+        }
+        Err(io::Error::other("the key changed while it was being read"))
+    }
+
+    /// Remove the stored secret. Succeeds when there is none.
+    pub fn clear(&self) -> io::Result<()> {
+        let Some(id) = find(self.description)? else {
+            return Ok(());
+        };
+        // SAFETY: plain integer arguments.
+        let rc = unsafe { libc::syscall(libc::SYS_keyctl, KEYCTL_REVOKE, id) };
+        if rc < 0 {
+            return match io::Error::last_os_error().raw_os_error() {
+                Some(libc::ENOKEY | libc::EKEYREVOKED) => Ok(()),
+                _ => last_error(),
+            };
+        }
+        Ok(())
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    // The kernel keyring is process-wide state and a sandbox may not offer it,
+    // so one test covers the whole round trip and skips when it is unavailable.
+    #[test]
+    fn stored_secret_round_trips_and_clears() {
+        if PASSPHRASES.store(b"probe").is_err() {
+            eprintln!("kernel keyring unavailable; skipping");
+            return;
+        }
+        let saved = PASSPHRASES
+            .load()
+            .unwrap()
+            .expect("stored secret is readable");
+        assert_eq!(saved.as_slice(), b"probe");
+
+        PASSPHRASES.store(b"replaced").unwrap();
+        assert_eq!(PASSPHRASES.load().unwrap().unwrap().as_slice(), b"replaced");
+
+        PASSPHRASES.clear().unwrap();
+        assert!(PASSPHRASES.load().unwrap().is_none());
+        PASSPHRASES.clear().unwrap();
+    }
+}

crates/pdfs-core/src/keycheck.rs

@@ -0,0 +1,294 @@
+//! Trace the key chain that opens My Files, for `pdfs diagnose`.
+//!
+//! The daemon only says "missing key" when the My Files share does not open
+//! (#40). This walks the chain the other way and names the link that breaks:
+//! the share's passphrase is encrypted to an address key, whose token is
+//! encrypted to an account key, which opens with the stored passphrase. Every
+//! finding holds key IDs and flags only, never key material, so the output is
+//! safe to post in an issue.
+
+use proton_sdk::account::{AddressKeyReport, KeyReport, UserKeyReport};
+use proton_sdk::ids::AddressId;
+
+use crate::auth;
+use crate::error::Result;
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+pub enum Level {
+    Ok,
+    Warn,
+    Fail,
+}
+
+#[derive(Debug, Clone, PartialEq, Eq)]
+pub struct Finding {
+    pub level: Level,
+    pub label: String,
+    pub detail: String,
+}
+
+/// The address and recipients of the My Files share passphrase, or why they
+/// could not be read.
+pub type ShareRecipients = std::result::Result<(AddressId, Vec<Option<String>>), String>;
+
+/// Resume the stored session and ask Proton for the account's keys and the
+/// My Files share. Fails when there is no session, the keys are locked, or
+/// Proton cannot be reached; reading the share is allowed to fail on its own.
+///
+/// The session's tokens are the daemon's too. A refresh here spends the
+/// refresh token the daemon holds, which it recovers from by resuming the
+/// stored session (see [`auth::stored_session_is_newer`]).
+pub async fn run() -> Result<(KeyReport, ShareRecipients)> {
+    let (client, _session) = auth::resume_client().await?;
+    let report = client.account().key_report().await?;
+    let share = client
+        .my_files_share_recipients()
+        .await
+        .map_err(|e| e.to_string());
+    Ok((report, share))
+}
+
+/// One finding per key, then one for the My Files share.
+pub fn findings(report: &KeyReport, share: &ShareRecipients) -> Vec<Finding> {
+    let mut findings = Vec::new();
+    for key in &report.user_keys {
+        findings.push(user_key_finding(key));
+    }
+    for address in &report.addresses {
+        for key in &address.keys {
+            findings.push(address_key_finding(report, &address.email, key));
+        }
+    }
+    findings.push(share_finding(report, share));
+    findings
+}
+
+fn user_key_finding(key: &UserKeyReport) -> Finding {
+    let label = format!("account key {}", short(key.id.as_str()));
+    let (level, detail) = match (key.active, key.unlocks) {
+        (true, true) => (Level::Ok, "opens".to_string()),
+        (true, false) => (
+            Level::Fail,
+            format!(
+                "does not open: {}",
+                key.error.as_deref().unwrap_or("unknown")
+            ),
+        ),
+        (false, true) => (Level::Ok, "inactive, opens with your password".to_string()),
+        (false, false) => (Level::Ok, "inactive, does not open".to_string()),
+    };
+    Finding {
+        level,
+        label,
+        detail: with_primary(key.primary, detail),
+    }
+}
+
+fn address_key_finding(report: &KeyReport, email: &str, key: &AddressKeyReport) -> Finding {
+    let label = format!("{email} key {}", short(key.id.as_str()));
+    let (level, detail) = if !key.active {
+        (Level::Ok, "inactive, not used".to_string())
+    } else if key.unlocks {
+        (Level::Ok, "opens".to_string())
+    } else {
+        // A non-primary key matters only for what was encrypted to it; the
+        // share finding says whether My Files is.
+        let level = if key.primary {
+            Level::Fail
+        } else {
+            Level::Warn
+        };
+        (level, format!("does not open: {}", why_closed(report, key)))
+    };
+    Finding {
+        level,
+        label,
+        detail: with_primary(key.primary, detail),
+    }
+}
+
+/// Why an active address key does not open, named by the account key its
+/// token was meant for when the token has one.
+fn why_closed(report: &KeyReport, key: &AddressKeyReport) -> String {
+    let error = key.error.as_deref().unwrap_or("unknown");
+    let Some(recipients) = &key.token_recipients else {
+        return error.to_string();
+    };
+    let named: Vec<&str> = recipients.iter().flatten().map(String::as_str).collect();
+    if let Some(user_key) = named.iter().find_map(|r| report.user_key_named(r)) {
+        let id = short(user_key.id.as_str());
+        return match (user_key.active, user_key.unlocks) {
+            (false, true) => {
+                format!(
+                    "its token is for inactive account key {id}, which opens with your password"
+                )
+            }
+            (false, false) => {
+                format!("its token is for inactive account key {id}, which does not open either")
+            }
+            (true, false) => format!("its token is for account key {id}, which does not open"),
+            // The token opened; the key itself refused its passphrase.
+            (true, true) => error.to_string(),
+        };
+    }
+    match named.first() {
+        Some(recipient) => {
+            format!("its token is for key {recipient}, which is none of your account keys")
+        }
+        None if recipients.is_empty() => error.to_string(),
+        None => "its token does not name the key it is for".to_string(),
+    }
+}
+
+fn share_finding(report: &KeyReport, share: &ShareRecipients) -> Finding {
+    let label = "My Files share".to_string();
+    let (level, detail) = match share {
+        Err(e) => (Level::Warn, format!("could not be read: {e}")),
+        Ok((address_id, recipients)) => {
+            let named: Vec<&str> = recipients.iter().flatten().map(String::as_str).collect();
+            match named.iter().find_map(|r| report.address_key_named(r)) {
+                Some((address, key)) => {
+                    let name = format!("{} key {}", address.email, short(key.id.as_str()));
+                    if key.unlocks {
+                        (Level::Ok, format!("encrypted to {name}, which opens"))
+                    } else {
+                        (
+                            Level::Fail,
+                            format!("encrypted to {name}, which does not open"),
+                        )
+                    }
+                }
+                None => (
+                    Level::Fail,
+                    match named.first() {
+                        Some(recipient) => format!(
+                            "encrypted to key {recipient}, which is none of the keys of address {address_id}"
+                        ),
+                        None => "its passphrase does not name the key it is for".to_string(),
+                    },
+                ),
+            }
+        }
+    };
+    Finding {
+        level,
+        label,
+        detail,
+    }
+}
+
+fn with_primary(primary: bool, detail: String) -> String {
+    if primary {
+        format!("primary, {detail}")
+    } else {
+        detail
+    }
+}
+
+/// The start of a Proton key ID: enough to tell keys apart and to find them
+/// in the daemon log, which prints the whole ID.
+fn short(id: &str) -> String {
+    match id.char_indices().nth(8) {
+        Some((end, _)) => format!("{}…", &id[..end]),
+        None => id.to_string(),
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use proton_sdk::account::AddressReport;
+    use proton_sdk::ids::{AddressKeyId, UserKeyId};
+
+    fn user_key(id: &str, active: bool, unlocks: bool, pgp: &str) -> UserKeyReport {
+        UserKeyReport {
+            id: UserKeyId::new(id),
+            primary: active,
+            active,
+            unlocks,
+            error: (!unlocks).then(|| "unlock: wrong passphrase".to_string()),
+            key_ids: vec![pgp.to_string()],
+        }
+    }
+
+    fn address_key(id: &str, primary: bool, token_for: &str, pgp: &str) -> AddressKeyReport {
+        AddressKeyReport {
+            id: AddressKeyId::new(id),
+            primary,
+            active: true,
+            token_recipients: Some(vec![Some(token_for.to_string())]),
+            unlocks: token_for == "u1",
+            error: (token_for != "u1").then(|| "token: failed to decrypt: missing key".to_string()),
+            key_ids: vec![pgp.to_string()],
+        }
+    }
+
+    /// The account in #40, as far as its log shows: the primary address key
+    /// opens, an older one does not, and My Files is encrypted to the older one.
+    fn report(stranded_token_for: &str) -> KeyReport {
+        KeyReport {
+            user_keys: vec![
+                user_key("UserKeyOne-123", true, true, "u1"),
+                user_key("UserKeyTwo-456", false, true, "u2"),
+            ],
+            addresses: vec![AddressReport {
+                id: AddressId::new("address-1"),
+                email: "user@proton.me".to_string(),
+                keys: vec![
+                    address_key("AddrKeyNew-789", true, "u1", "a1"),
+                    address_key("AddrKeyOld-000", false, stranded_token_for, "a2"),
+                ],
+            }],
+        }
+    }
+
+    #[test]
+    fn a_stranded_address_key_is_traced_to_the_inactive_account_key() {
+        let report = report("u2");
+        let share = Ok((AddressId::new("address-1"), vec![Some("a2".to_string())]));
+        let findings = findings(&report, &share);
+
+        assert_eq!(findings[0].detail, "primary, opens");
+        assert_eq!(findings[1].detail, "inactive, opens with your password");
+        assert_eq!(findings[2].level, Level::Ok);
+        assert_eq!(findings[3].level, Level::Warn);
+        assert_eq!(findings[3].label, "user@proton.me key AddrKeyO…");
+        assert_eq!(
+            findings[3].detail,
+            "does not open: its token is for inactive account key UserKeyT…, which opens with your password"
+        );
+        assert_eq!(findings[4].level, Level::Fail);
+        assert_eq!(
+            findings[4].detail,
+            "encrypted to user@proton.me key AddrKeyO…, which does not open"
+        );
+    }
+
+    #[test]
+    fn a_token_for_a_key_the_account_does_not_list_says_so() {
+        let report = report("ffff");
+        let detail = &findings(&report, &Err("offline".to_string()))[3].detail;
+        assert_eq!(
+            detail,
+            "does not open: its token is for key ffff, which is none of your account keys"
+        );
+    }
+
+    #[test]
+    fn a_share_that_opens_and_one_that_cannot_be_read() {
+        let report = report("u2");
+        let open = Ok((AddressId::new("address-1"), vec![Some("a1".to_string())]));
+        let last = findings(&report, &open).pop().unwrap();
+        assert_eq!(last.level, Level::Ok);
+        assert_eq!(
+            last.detail,
+            "encrypted to user@proton.me key AddrKeyN…, which opens"
+        );
+
+        let last = findings(&report, &Err("offline".to_string()))
+            .pop()
+            .unwrap();
+        assert_eq!(last.level, Level::Warn);
+        assert_eq!(last.detail, "could not be read: offline");
+    }
+}

crates/pdfs-core/src/lib.rs

@@ -10,8 +10,13 @@ pub mod config;
 pub mod control;
 pub mod db;
 pub mod error;
+pub mod exiftime;
+pub mod kernelkey;
+pub mod keycheck;
 pub mod localindex;
 pub mod menu;
+pub mod mountfail;
+pub mod mountpoint;
 pub mod mounts;
 pub mod opener;
 pub mod places;
@@ -22,8 +27,10 @@ pub mod service;
 pub mod shell;
 pub mod similar;
 pub mod syncignore;
+pub mod syncroot;
 pub mod takeout;
 pub mod tray;
+pub mod update;
 
 pub use access::{Access, access_for, perm_bits};
 pub use error::{CoreError, CoreResult, Error, Result};

crates/pdfs-core/src/localindex.rs

@@ -42,7 +42,7 @@ const SKIP_PATH_SUFFIXES: &[&str] = &["go/pkg/mod"];
 
 /// Hard cap on indexed entries, so a pathological home directory cannot grow the
 /// database without bound. Reaching it stops the walk early.
-const MAX_ENTRIES: usize = 400_000;
+pub const MAX_ENTRIES: usize = 400_000;
 
 /// Rows handed to the sink at a time. Large enough that the per-transaction cost
 /// amortises, small enough that the writer lock is released often (FUSE

crates/pdfs-core/src/mountfail.rs

@@ -0,0 +1,89 @@
+//! Why the daemon's mount keeps failing, for the front ends to read.
+//!
+//! The control socket opens only once a mount has succeeded, so a daemon whose
+//! mount fails on every try had no way to say why. The app and the tray showed
+//! "Connecting…" for days while the reason sat in the journal (`docs/BUGS.md`
+//! B263). The daemon now writes its last failure to a small file in the state
+//! directory, next to the control socket, and removes it once a mount is up.
+
+use std::path::{Path, PathBuf};
+
+use serde::{Deserialize, Serialize};
+
+/// The file's name inside the state directory.
+const FILE_NAME: &str = "mount-failure.json";
+
+/// The last failed mount attempt.
+#[derive(Serialize, Deserialize, Debug, Clone, PartialEq, Eq)]
+pub struct MountFailure {
+    /// The error, in English, as the journal has it.
+    pub error: String,
+    /// Unix seconds of the first failure in this run of failures.
+    pub since: i64,
+    /// Failed attempts in a row.
+    pub attempts: u32,
+    /// Unix seconds of the next attempt.
+    pub next_attempt: i64,
+    /// Set when the mount was refused because the folder already has files in
+    /// it, so the app can explain that in the user's language. Absent in a
+    /// file an older daemon wrote.
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    pub not_empty: Option<crate::mountpoint::NotEmpty>,
+}
+
+/// Where the failure is kept for the state directory `state_dir`.
+pub fn path(state_dir: &Path) -> PathBuf {
+    state_dir.join(FILE_NAME)
+}
+
+/// Record `failure`, replacing the one before it. Written to a temporary file
+/// and renamed, so a reader never sees half of it.
+pub fn record(state_dir: &Path, failure: &MountFailure) -> std::io::Result<()> {
+    let json = serde_json::to_vec(failure).map_err(std::io::Error::other)?;
+    let tmp = state_dir.join(format!("{FILE_NAME}.tmp"));
+    std::fs::write(&tmp, json)?;
+    std::fs::rename(&tmp, path(state_dir))
+}
+
+/// Forget the failure: a mount is up, or a new daemon has started.
+pub fn clear(state_dir: &Path) {
+    let _ = std::fs::remove_file(path(state_dir));
+}
+
+/// The recorded failure, if there is one and it can be read.
+pub fn read(state_dir: &Path) -> Option<MountFailure> {
+    let bytes = std::fs::read(path(state_dir)).ok()?;
+    serde_json::from_slice(&bytes).ok()
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn a_recorded_failure_reads_back_until_cleared() {
+        let dir = std::env::temp_dir().join(format!("pdfs-mountfail-{}", std::process::id()));
+        std::fs::create_dir_all(&dir).unwrap();
+        assert_eq!(read(&dir), None);
+        let failure = MountFailure {
+            error: "fetch My Files root: missing key".into(),
+            since: 1_700_000_000,
+            attempts: 3,
+            next_attempt: 1_700_000_040,
+            not_empty: None,
+        };
+        record(&dir, &failure).unwrap();
+        assert_eq!(read(&dir), Some(failure));
+        clear(&dir);
+        assert_eq!(read(&dir), None);
+        let _ = std::fs::remove_dir_all(&dir);
+    }
+
+    #[test]
+    fn a_failure_an_older_daemon_wrote_still_reads() {
+        let old = r#"{"error":"missing key","since":1,"attempts":2,"next_attempt":3}"#;
+        let failure: MountFailure = serde_json::from_str(old).unwrap();
+        assert_eq!(failure.not_empty, None);
+        assert_eq!(failure.attempts, 2);
+    }
+}

crates/pdfs-core/src/mountpoint.rs

@@ -0,0 +1,147 @@
+//! Whether a folder can take the My files mount without hiding anything.
+//!
+//! FUSE mounts over a folder that already has files in it without a word. The
+//! files then sit under the mount, out of sight: not uploaded, and back only
+//! once the service stops, so they look deleted (`docs/BUGS.md` B277, #67).
+//! The daemon refuses such a folder, and the app refuses it when it is picked.
+
+use std::path::{Path, PathBuf};
+
+use serde::{Deserialize, Serialize};
+
+/// The file system type the kernel reports for this client's own mounts.
+pub const OWN_FS_TYPE: &str = "fuse.protondrive";
+
+/// How many of a folder's entries an error names.
+const NAMED_ENTRIES: usize = 3;
+
+/// A folder that already has something in it.
+#[derive(Serialize, Deserialize, Debug, Clone, PartialEq, Eq)]
+pub struct NotEmpty {
+    /// The folder.
+    pub path: PathBuf,
+    /// The first few names in it, sorted.
+    pub entries: Vec<String>,
+    /// How many entries it has in all.
+    pub count: usize,
+}
+
+impl std::fmt::Display for NotEmpty {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        write!(f, "{} is not empty (holds ", self.path.display())?;
+        write!(f, "{}", self.entries.join(", "))?;
+        let rest = self.count.saturating_sub(self.entries.len());
+        if rest > 0 {
+            write!(f, " and {rest} more")?;
+        }
+        write!(
+            f,
+            "); My files would hide those files. Move them out, or choose another folder for My files"
+        )
+    }
+}
+
+impl std::error::Error for NotEmpty {}
+
+/// What is in `dir`, if anything. A folder that does not exist yet is empty.
+/// Hidden entries count: a `.directory` or a `.Trash-1000` hidden under the
+/// mount is as lost as any other file.
+pub fn not_empty(dir: &Path) -> std::io::Result<Option<NotEmpty>> {
+    let read = match std::fs::read_dir(dir) {
+        Ok(read) => read,
+        Err(e) if e.kind() == std::io::ErrorKind::NotFound => return Ok(None),
+        Err(e) => return Err(e),
+    };
+    let mut names = read
+        .map(|entry| entry.map(|entry| entry.file_name().to_string_lossy().into_owned()))
+        .collect::<std::io::Result<Vec<_>>>()?;
+    if names.is_empty() {
+        return Ok(None);
+    }
+    names.sort();
+    let count = names.len();
+    names.truncate(NAMED_ENTRIES);
+    Ok(Some(NotEmpty {
+        path: dir.to_path_buf(),
+        entries: names,
+        count,
+    }))
+}
+
+/// The file system type mounted at `path`, as `/proc/self/mountinfo` names it
+/// (`ext4`, `fuse.protondrive`, …), or `None` when nothing is mounted there.
+pub fn mounted_fs_type(path: &Path) -> Option<String> {
+    let wanted = path.canonicalize().ok()?;
+    let mounts = std::fs::read_to_string("/proc/self/mountinfo").ok()?;
+    mounts
+        .lines()
+        .filter_map(|line| {
+            let fields: Vec<_> = line.split_whitespace().collect();
+            let separator = fields.iter().position(|field| *field == "-")?;
+            let encoded = *fields.get(4)?;
+            let decoded = encoded.replace("\\040", " ").replace("\\011", "\t");
+            let mountpoint = PathBuf::from(decoded);
+            if mountpoint.canonicalize().ok()? == wanted {
+                Some(fields.get(separator + 1)?.to_string())
+            } else {
+                None
+            }
+        })
+        .next()
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    fn temp_dir(name: &str) -> PathBuf {
+        let dir =
+            std::env::temp_dir().join(format!("pdfs-mountpoint-{name}-{}", std::process::id()));
+        let _ = std::fs::remove_dir_all(&dir);
+        std::fs::create_dir_all(&dir).unwrap();
+        dir
+    }
+
+    #[test]
+    fn an_empty_or_missing_folder_takes_the_mount() {
+        let dir = temp_dir("empty");
+        assert_eq!(not_empty(&dir).unwrap(), None);
+        assert_eq!(not_empty(&dir.join("missing")).unwrap(), None);
+        let _ = std::fs::remove_dir_all(&dir);
+    }
+
+    #[test]
+    fn a_folder_with_files_is_refused_and_named() {
+        let dir = temp_dir("files");
+        for name in ["report.pdf", "Notes", ".directory", "zeta.txt"] {
+            std::fs::write(dir.join(name), b"x").unwrap();
+        }
+        let found = not_empty(&dir).unwrap().expect("must refuse");
+        assert_eq!(found.count, 4);
+        assert_eq!(found.entries, [".directory", "Notes", "report.pdf"]);
+        let message = found.to_string();
+        assert!(message.contains("is not empty"), "{message}");
+        assert!(
+            message.contains(".directory, Notes, report.pdf and 1 more"),
+            "{message}"
+        );
+        let _ = std::fs::remove_dir_all(&dir);
+    }
+
+    #[test]
+    fn a_hidden_file_alone_is_enough_to_refuse() {
+        let dir = temp_dir("hidden");
+        std::fs::write(dir.join(".Trash-1000"), b"").unwrap();
+        let found = not_empty(&dir).unwrap().expect("must refuse");
+        assert_eq!(found.count, 1);
+        assert!(!found.to_string().contains("more"));
+        let _ = std::fs::remove_dir_all(&dir);
+    }
+
+    #[test]
+    fn a_plain_folder_is_not_a_mount() {
+        let dir = temp_dir("plain");
+        assert_eq!(mounted_fs_type(&dir), None);
+        let _ = std::fs::remove_dir_all(&dir);
+    }
+}

crates/pdfs-core/src/opener.rs

@@ -189,11 +189,21 @@ fn spawn(argv: &[String], path: &Path) {
         .stderr(Stdio::null())
         .process_group(0)
         .spawn();
-    if let Err(e) = spawned {
-        tracing::error!(command = ?argv, "open failed: {e}");
+    match spawned {
+        Ok(child) => reap(child),
+        Err(e) => tracing::error!(command = ?argv, "open failed: {e}"),
     }
 }
 
+/// Wait for `child` on a thread of its own. A child nobody waits for stays a
+/// zombie for as long as its parent lives, which for the app and the tray is
+/// the whole session.
+pub fn reap(mut child: std::process::Child) {
+    std::thread::spawn(move || {
+        let _ = child.wait();
+    });
+}
+
 /// [`open`] with the policy from the user's `config.json`, read once per
 /// process. For callers that open the occasional path and have no reason to
 /// carry a policy around; long-lived windows should hold their own copy.
@@ -472,6 +482,21 @@ fn glob_match(pattern: &str, name: &str) -> bool {
 mod tests {
     use super::*;
 
+    #[test]
+    fn a_reaped_child_does_not_stay_a_zombie() {
+        let child = std::process::Command::new("true").spawn().unwrap();
+        let proc_entry = std::path::PathBuf::from(format!("/proc/{}", child.id()));
+        reap(child);
+        let deadline = std::time::Instant::now() + std::time::Duration::from_secs(5);
+        while proc_entry.exists() && std::time::Instant::now() < deadline {
+            std::thread::sleep(std::time::Duration::from_millis(10));
+        }
+        assert!(
+            !proc_entry.exists(),
+            "the child is still in the process table"
+        );
+    }
+
     fn rule(patterns: &[&str], command: &[&str], terminal: bool) -> OpenRule {
         OpenRule {
             patterns: patterns.iter().map(|p| (*p).to_string()).collect(),

crates/pdfs-core/src/profile.rs

@@ -19,9 +19,31 @@ use serde::{Deserialize, Serialize};
 
 use crate::mounts::MountMode;
 
-/// File name of the profile.
+/// File name of the profile clients before 3.5.0 wrote, one per device.
+///
+/// Read, never written: two computers sharing a device each overwrote the
+/// other's. See [`profile_file_name`].
 pub const PROFILE_FILE_NAME: &str = "profile.json";
 
+/// File name of one machine's profile: `profile-<machine id>.json`.
+///
+/// One per machine, because several computers may sync into one device, and
+/// each describes its own arrangement. A single shared file went to whichever
+/// computer saved last.
+pub fn profile_file_name(machine_id: &str) -> String {
+    format!("profile-{machine_id}.json")
+}
+
+/// Whether `name` is a profile: [`PROFILE_FILE_NAME`] or one machine's
+/// [`profile_file_name`].
+pub fn is_profile_file_name(name: &str) -> bool {
+    name == PROFILE_FILE_NAME
+        || name
+            .strip_prefix("profile-")
+            .and_then(|rest| rest.strip_suffix(".json"))
+            .is_some_and(|id| !id.is_empty() && id.bytes().all(|b| b.is_ascii_alphanumeric()))
+}
+
 /// Folder, directly under the device root, that holds the profile.
 ///
 /// The API refuses `Cannot create file at the root of a device` (HTTP 422), so
@@ -74,6 +96,10 @@ pub struct Profile {
     /// Hostname of the machine that wrote it, so a restore prompt can say
     /// *"restore settings from laptop-xyz?"* rather than quoting a uid.
     pub hostname: String,
+    /// The writing machine's id, as in its [`profile_file_name`]. `None` in a
+    /// profile written before 3.5.0.
+    #[serde(default)]
+    pub machine_id: Option<String>,
     /// When it was written, epoch seconds.
     pub saved_at: i64,
     #[serde(default)]
@@ -92,6 +118,25 @@ pub struct Profile {
     pub mountpoint: Option<String>,
 }
 
+/// The saved arrangement of the folder with uid `remote_uid`, from the
+/// profiles of every computer that syncs the device.
+///
+/// The profile of the machine named `hostname` wins, since it describes this
+/// computer; otherwise the most recently saved one that has the folder.
+pub fn saved_folder<'a>(
+    profiles: &'a [Profile],
+    remote_uid: &str,
+    hostname: &str,
+) -> Option<&'a ProfileFolder> {
+    let holding = |p: &&'a Profile| p.folders.iter().any(|f| f.remote_uid == remote_uid);
+    let profile = profiles
+        .iter()
+        .filter(holding)
+        .find(|p| p.hostname == hostname)
+        .or_else(|| profiles.iter().filter(holding).max_by_key(|p| p.saved_at))?;
+    profile.folders.iter().find(|f| f.remote_uid == remote_uid)
+}
+
 impl Profile {
     /// Parse a profile document, refusing one written by a newer client.
     pub fn parse(bytes: &[u8]) -> Result<Self, String> {
@@ -122,6 +167,7 @@ mod tests {
             version: PROFILE_VERSION,
             device_uid: "dev-1".to_string(),
             hostname: "laptop-xyz".to_string(),
+            machine_id: Some("0123456789abcdef0123456789abcdef".to_string()),
             saved_at: 1_700_000_000,
             folders: vec![ProfileFolder {
                 remote_uid: "vol~link".to_string(),
@@ -219,6 +265,52 @@ mod tests {
         assert!(p.ignore_patterns.is_none());
     }
 
+    #[test]
+    fn a_profile_name_is_the_legacy_one_or_one_per_machine() {
+        assert!(is_profile_file_name(PROFILE_FILE_NAME));
+        let name = profile_file_name("0123456789abcdef0123456789abcdef");
+        assert_eq!(name, "profile-0123456789abcdef0123456789abcdef.json");
+        assert!(is_profile_file_name(&name));
+        assert!(!is_profile_file_name("profile-.json"));
+        assert!(!is_profile_file_name("profile-a/b.json"));
+        assert!(!is_profile_file_name("profile (1).json"));
+        assert!(!is_profile_file_name("notes.json"));
+    }
+
+    /// A profile written before 3.5.0 has no machine id and still parses.
+    #[test]
+    fn a_profile_without_a_machine_id_parses() {
+        let json = br#"{"version":1,"device_uid":"d","hostname":"h","saved_at":0}"#;
+        assert_eq!(Profile::parse(json).unwrap().machine_id, None);
+    }
+
+    /// Several computers sync one device, each with its own profile. This
+    /// computer's own wins, then the newest that has the folder.
+    #[test]
+    fn the_saved_folder_comes_from_this_computer_then_the_newest_profile() {
+        let profile = |hostname: &str, saved_at: i64, path: &str| Profile {
+            hostname: hostname.to_string(),
+            saved_at,
+            folders: vec![ProfileFolder {
+                remote_uid: "vol~docs".to_string(),
+                local_path: path.to_string(),
+                mode: MountMode::Mirror,
+            }],
+            ..sample()
+        };
+        let profiles = vec![
+            profile("desktop", 10, "/home/a/Docs"),
+            profile("laptop", 5, "/home/b/Docs"),
+            profile("old", 1, "/home/c/Docs"),
+        ];
+        let path =
+            |host: &str| saved_folder(&profiles, "vol~docs", host).map(|f| f.local_path.as_str());
+        assert_eq!(path("laptop"), Some("/home/b/Docs"));
+        assert_eq!(path("new-machine"), Some("/home/a/Docs"));
+        assert_eq!(saved_folder(&profiles, "vol~other", "laptop"), None);
+        assert_eq!(saved_folder(&[], "vol~docs", "laptop"), None);
+    }
+
     #[test]
     fn future_version_is_refused() {
         let mut p = sample();

crates/pdfs-core/src/shell.rs

@@ -23,6 +23,11 @@ const SCRIPTS: [(&str, &str); 2] = [
 /// `NAUTILUS_SCRIPT_SELECTED_FILE_PATHS`; the positional args carry the same
 /// selection when the script runs on a local (non-URI) folder, so we prefer the
 /// environment and fall back to `"$@"` for the Nemo/Caja variants.
+///
+/// The `--` keeps a file named like an option, such as `--json`, a path. A
+/// name with a newline in it still arrives split in two from Nautilus, whose
+/// list is newline-separated; `pdfs` then fails on both halves, which touches
+/// nothing.
 fn script_body(subcommand: &str) -> String {
     format!(
         "#!/bin/sh\n\
@@ -41,7 +46,7 @@ fn script_body(subcommand: &str) -> String {
          \n\
          printf '%s' \"$paths\" | while IFS= read -r path; do\n\
          \x20   [ -n \"$path\" ] || continue\n\
-         \x20   pdfs {subcommand} \"$path\" || exit 1\n\
+         \x20   pdfs {subcommand} -- \"$path\" || exit 1\n\
          done\n"
     )
 }
@@ -95,3 +100,13 @@ fn write_scripts(dir: &PathBuf) -> io::Result<()> {
     tracing::debug!("installed file-manager scripts in {dir:?}");
     Ok(())
 }
+
+#[cfg(test)]
+mod tests {
+    use super::script_body;
+
+    #[test]
+    fn the_script_ends_options_before_each_path() {
+        assert!(script_body("pin").contains(r#"pdfs pin -- "$path""#));
+    }
+}

crates/pdfs-core/src/syncroot.rs

@@ -0,0 +1,209 @@
+//! Which local folders may become a sync root.
+//!
+//! A mirror uploads everything under its root and deletes what Drive deleted,
+//! so a root that holds more than the user meant is dangerous. `$HOME` takes
+//! the decrypted content cache, `cache.db` and `~/.ssh` up to Drive, and walks
+//! into the mount, which downloads the whole Drive only to upload it again.
+//! Every place a root is added or restored goes through [`problem`].
+
+use std::path::{Component, Path, PathBuf};
+
+use crate::config::{AppConfig, AppDirs};
+
+/// The paths a sync root must stay clear of.
+#[derive(Debug, Clone, Default)]
+pub struct Reserved {
+    /// The user's home folder. A root may sit inside it, not be it or above it.
+    pub home: Option<PathBuf>,
+    /// The Proton Drive mount.
+    pub mountpoint: Option<PathBuf>,
+    /// This app's own configuration, state and cache folders.
+    pub app_dirs: Vec<PathBuf>,
+}
+
+impl Reserved {
+    /// The reserved paths of this user and `config`, resolved like a root.
+    pub fn current(config: &AppConfig) -> Self {
+        let Ok(dirs) = AppDirs::new() else {
+            return Self::default();
+        };
+        let resolved = |path: PathBuf| resolve(&path).unwrap_or(path);
+        let mut app_dirs = vec![dirs.state_dir(), dirs.cache_dir()];
+        if let Some(config_dir) = dirs.config_path().parent() {
+            app_dirs.push(config_dir.to_path_buf());
+        }
+        Self {
+            home: dirs.home_dir().map(resolved),
+            mountpoint: Some(resolved(dirs.resolved_mountpoint(config))),
+            app_dirs: app_dirs.into_iter().map(resolved).collect(),
+        }
+    }
+}
+
+/// `path` as a root is compared: absolute, with symlinks resolved as far as the
+/// path exists. A folder a restore is about to create does not exist yet, so
+/// the part past the deepest existing folder is kept as written.
+///
+/// A `..` is refused rather than resolved: before a symlink it means something
+/// else than after it, and a path recorded on another machine has no business
+/// holding one.
+pub fn resolve(path: &Path) -> Result<PathBuf, String> {
+    if !path.is_absolute() {
+        return Err(format!("{} is not an absolute path", path.display()));
+    }
+    if path.components().any(|c| c == Component::ParentDir) {
+        return Err(format!("{} goes up with `..`", path.display()));
+    }
+    let mut existing = path.to_path_buf();
+    let mut rest = Vec::new();
+    loop {
+        match existing.canonicalize() {
+            Ok(canonical) => {
+                return Ok(rest
+                    .into_iter()
+                    .rev()
+                    .fold(canonical, |path: PathBuf, part| path.join(part)));
+            }
+            Err(_) => {
+                let Some(name) = existing.file_name().map(|n| n.to_os_string()) else {
+                    return Ok(path.to_path_buf());
+                };
+                rest.push(name);
+                if !existing.pop() {
+                    return Ok(path.to_path_buf());
+                }
+            }
+        }
+    }
+}
+
+/// Why `root` cannot be synced, or `None` when it can. `root` is resolved
+/// ([`resolve`]); `others` are the roots already synced.
+pub fn problem(root: &Path, others: &[PathBuf], reserved: &Reserved) -> Option<String> {
+    let shown = root.display();
+    if root.parent().is_none() {
+        return Some(format!("{shown} is the root of the file system"));
+    }
+    if let Some(home) = &reserved.home {
+        if root == home {
+            return Some(format!(
+                "{shown} is your home folder; pick a folder inside it"
+            ));
+        }
+        if home.starts_with(root) {
+            return Some(format!("{shown} holds your home folder"));
+        }
+    }
+    if let Some(mountpoint) = &reserved.mountpoint
+        && overlaps(root, mountpoint)
+    {
+        return Some(format!(
+            "{shown} overlaps the Proton Drive folder {}",
+            mountpoint.display()
+        ));
+    }
+    if let Some(dir) = reserved.app_dirs.iter().find(|dir| overlaps(root, dir)) {
+        return Some(format!(
+            "{shown} overlaps this app's own data in {}",
+            dir.display()
+        ));
+    }
+    if others.iter().any(|other| other == root) {
+        return Some(format!("{shown} is already synced"));
+    }
+    if let Some(other) = others.iter().find(|other| overlaps(root, other)) {
+        return Some(format!(
+            "{shown} overlaps the synced folder {}",
+            other.display()
+        ));
+    }
+    None
+}
+
+/// Whether one of `a` and `b` is the other or inside it.
+fn overlaps(a: &Path, b: &Path) -> bool {
+    a.starts_with(b) || b.starts_with(a)
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    fn reserved() -> Reserved {
+        Reserved {
+            home: Some("/home/u".into()),
+            mountpoint: Some("/home/u/ProtonDrive".into()),
+            app_dirs: vec![
+                "/home/u/.local/state/proton-drive-linux".into(),
+                "/home/u/.cache/proton-drive-linux".into(),
+                "/home/u/.config/proton-drive-linux".into(),
+            ],
+        }
+    }
+
+    fn refused(root: &str, others: &[&str]) -> bool {
+        let others: Vec<PathBuf> = others.iter().map(PathBuf::from).collect();
+        problem(Path::new(root), &others, &reserved()).is_some()
+    }
+
+    #[test]
+    fn a_folder_inside_home_can_be_synced() {
+        assert!(!refused("/home/u/Documents", &[]));
+        assert!(!refused("/home/u/Pictures", &["/home/u/Documents"]));
+        assert!(!refused("/mnt/data/photos", &[]));
+    }
+
+    #[test]
+    fn the_file_system_root_home_and_its_parents_are_refused() {
+        assert!(refused("/", &[]));
+        assert!(refused("/home/u", &[]));
+        assert!(refused("/home", &[]));
+    }
+
+    #[test]
+    fn the_mount_and_the_apps_own_data_are_refused_either_way_round() {
+        assert!(refused("/home/u/ProtonDrive", &[]));
+        assert!(refused("/home/u/ProtonDrive/Documents", &[]));
+        assert!(refused("/home/u/.cache", &[]));
+        assert!(refused(
+            "/home/u/.local/state/proton-drive-linux/staging",
+            &[]
+        ));
+        assert!(refused("/home/u/.config", &[]));
+    }
+
+    #[test]
+    fn a_root_inside_or_around_another_root_is_refused() {
+        assert!(refused("/home/u/Documents", &["/home/u/Documents"]));
+        assert!(refused("/home/u/Documents/Work", &["/home/u/Documents"]));
+        assert!(refused("/home/u/stuff", &["/home/u/stuff/Documents"]));
+        // A shared prefix of characters is not a shared folder.
+        assert!(!refused("/home/u/Documents2", &["/home/u/Documents"]));
+    }
+
+    #[test]
+    fn a_path_that_goes_up_or_is_relative_does_not_resolve() {
+        assert!(resolve(Path::new("/home/u/../../etc")).is_err());
+        assert!(resolve(Path::new("Documents")).is_err());
+    }
+
+    #[test]
+    fn a_folder_still_to_be_created_resolves_under_its_existing_parent() {
+        let base = std::env::temp_dir().join(format!("pdfs-syncroot-{}", std::process::id()));
+        std::fs::create_dir_all(&base).unwrap();
+        let canonical = base.canonicalize().unwrap();
+        assert_eq!(
+            resolve(&base.join("new/inner")).unwrap(),
+            canonical.join("new/inner")
+        );
+        let link = base.join("link");
+        let _ = std::fs::remove_file(&link);
+        std::os::unix::fs::symlink(&canonical, &link).unwrap();
+        assert_eq!(
+            resolve(&link.join("later")).unwrap(),
+            canonical.join("later"),
+            "a symlink is followed to where it points"
+        );
+        std::fs::remove_dir_all(&base).unwrap();
+    }
+}

crates/pdfs-core/src/takeout.rs

@@ -346,6 +346,11 @@ fn assemble(entries: Vec<RawEntry>, sidecars: &HashMap<String, Vec<u8>>) -> Take
             .insert(file.to_string(), body);
     }
 
+    let indexes: HashMap<&str, SidecarIndex<'_>> = per_folder_sidecars
+        .iter()
+        .map(|(folder, in_folder)| (folder.as_str(), SidecarIndex::new(in_folder)))
+        .collect();
+
     let mut scan = TakeoutScan::default();
     let mut seen_albums: HashMap<String, ()> = HashMap::new();
 
@@ -364,9 +369,13 @@ fn assemble(entries: Vec<RawEntry>, sidecars: &HashMap<String, Vec<u8>>) -> Take
             continue;
         };
 
-        let sidecar = per_folder_sidecars
-            .get(&folder)
-            .and_then(|in_folder| find_sidecar(&file_name, in_folder))
+        let found = indexes
+            .get(folder.as_str())
+            .and_then(|index| find_sidecar(&file_name, index));
+        // An edited copy keeps its own name: the title is its original's.
+        let title_is_ours = found.is_some_and(|((rule, _), _)| rule != EDITED_COPY);
+        let sidecar = found
+            .map(|(_, body)| body)
             .and_then(|body| serde_json::from_slice::<PhotoSidecar>(body).ok())
             .unwrap_or_default();
 
@@ -388,6 +397,7 @@ fn assemble(entries: Vec<RawEntry>, sidecars: &HashMap<String, Vec<u8>>) -> Take
         let name = sidecar
             .title
             .as_deref()
+            .filter(|_| title_is_ours)
             .map(str::trim)
             .filter(|title| !title.is_empty() && same_extension(title, &file_name))
             .unwrap_or(&file_name)
@@ -598,7 +608,7 @@ pub fn capture_time_from_name(name: &str) -> Option<i64> {
 
 /// Days between 1970-01-01 and a proleptic-Gregorian date (Howard Hinnant's
 /// `days_from_civil`). Avoids pulling a date crate in for one conversion.
-fn days_from_civil(year: i64, month: i64, day: i64) -> i64 {
+pub(crate) fn days_from_civil(year: i64, month: i64, day: i64) -> i64 {
     let year = year - i64::from(month <= 2);
     let era = if year >= 0 { year } else { year - 399 } / 400;
     let year_of_era = year - era * 400;
@@ -627,17 +637,106 @@ fn swap_duplicate_marker(file_name: &str) -> Option<String> {
     Some(format!("{}{}{}", &file_name[..marker_start], tail, marker))
 }
 
-/// Find the sidecar belonging to `file_name` among the JSON files of its folder.
+/// How long Google lets a sidecar's file name get, `.json` included. A longer
+/// one is cut, into its suffix first and then into the photo name.
+const SIDECAR_NAME_CAP: usize = 51;
+
+/// The rank [`sidecar_rank`] gives an edited copy that shares its original's
+/// sidecar. Its date is the original's, but its name is its own.
+const EDITED_COPY: u8 = 4;
+
+/// The sidecars of one folder by their `.json`-stripped stem, so a photo is
+/// ranked only against those that can match it.
+///
+/// Every rule in [`sidecar_rank`] needs the stem to start with a prefix of the
+/// photo name that the name itself determines, and a sorted map finds the
+/// stems with a given prefix as one range. Ranking every photo against every
+/// sidecar instead took 27 s for a folder of 10,000 photos.
+struct SidecarIndex<'a> {
+    by_stem: BTreeMap<&'a str, Vec<(&'a str, &'a Vec<u8>)>>,
+}
+
+impl<'a> SidecarIndex<'a> {
+    fn new(in_folder: &'a BTreeMap<String, &'a Vec<u8>>) -> Self {
+        let mut by_stem: BTreeMap<&'a str, Vec<(&'a str, &'a Vec<u8>)>> = BTreeMap::new();
+        for (name, body) in in_folder {
+            by_stem
+                .entry(strip_json_suffix(name))
+                .or_default()
+                .push((name.as_str(), *body));
+        }
+        Self { by_stem }
+    }
+
+    /// Add every sidecar whose stem starts with `prefix` to `out`.
+    fn starting_with(&self, prefix: &str, out: &mut BTreeMap<&'a str, &'a Vec<u8>>) {
+        let from = (
+            std::ops::Bound::Included(prefix),
+            std::ops::Bound::Unbounded,
+        );
+        for (stem, sidecars) in self.by_stem.range::<str, _>(from) {
+            if !stem.starts_with(prefix) {
+                break;
+            }
+            out.extend(sidecars.iter().copied());
+        }
+    }
+
+    /// Add every sidecar whose stem is `head`, or starts with `head` and a `.`:
+    /// those that have `head` as a boundary ([`suffix_boundaries`]).
+    fn bounded_by(&self, head: &str, out: &mut BTreeMap<&'a str, &'a Vec<u8>>) {
+        if let Some(sidecars) = self.by_stem.get(head) {
+            out.extend(sidecars.iter().copied());
+        }
+        self.starting_with(&format!("{head}."), out);
+    }
+
+    /// Every sidecar [`sidecar_rank`] could match `file_name` to, by name. A
+    /// superset: each one is still ranked.
+    fn candidates(&self, file_name: &str) -> BTreeMap<&'a str, &'a Vec<u8>> {
+        let mut out = BTreeMap::new();
+        // Rules 0 and 2: the stem starts with the name, or with its swapped form.
+        self.starting_with(file_name, &mut out);
+        if let Some(swapped) = swap_duplicate_marker(file_name) {
+            self.starting_with(&swapped, &mut out);
+        }
+        // Rule 1: the stem of `A(N).B` starts with `A.B(N)`, so with `A.`.
+        for (paren, _) in file_name.match_indices('(') {
+            self.starting_with(&format!("{}.", &file_name[..paren]), &mut out);
+        }
+        // Rule 3: a boundary of the stem is a prefix of the name.
+        for end in file_name
+            .char_indices()
+            .map(|(index, _)| index)
+            .skip(1)
+            .chain([file_name.len()])
+        {
+            self.bounded_by(&file_name[..end], &mut out);
+        }
+        // Rule 4: `<original>-<word>.<ext>` has `<original>.<ext>` as a boundary.
+        if let Some((_, extension)) = file_name.rsplit_once('.') {
+            for (dash, _) in file_name.match_indices('-') {
+                self.bounded_by(&format!("{}.{extension}", &file_name[..dash]), &mut out);
+            }
+        }
+        out
+    }
+}
+
+/// Find the sidecar belonging to `file_name` among the JSON files of its folder,
+/// with the rank it matched at.
 ///
 /// Tried in order of confidence: the exact name, the `(N)`-swapped name, an
-/// unknown trailing suffix, then a prefix match for the case where truncation
-/// cut into the photo name itself. The best-ranked candidate in the folder wins.
+/// unknown trailing suffix, a prefix match for the case where truncation cut
+/// into the photo name itself, and last an edited copy's original. The
+/// best-ranked candidate in the folder wins; of equal ranks, the first by
+/// sidecar name.
 fn find_sidecar<'a>(
     file_name: &str,
-    in_folder: &BTreeMap<String, &'a Vec<u8>>,
-) -> Option<&'a Vec<u8>> {
+    index: &SidecarIndex<'a>,
+) -> Option<((u8, usize), &'a Vec<u8>)> {
     let mut best: Option<((u8, usize), &'a Vec<u8>)> = None;
-    for (sidecar_name, body) in in_folder {
+    for (sidecar_name, body) in index.candidates(file_name) {
         let Some(rank) = sidecar_rank(strip_json_suffix(sidecar_name), file_name) else {
             continue;
         };
@@ -645,7 +744,7 @@ fn find_sidecar<'a>(
             best = Some((rank, body));
         }
     }
-    best.map(|(_, body)| body)
+    best
 }
 
 /// How well a sidecar's `.json`-stripped `stem` matches `file_name`, as a sort
@@ -683,19 +782,44 @@ fn sidecar_rank(stem: &str, file_name: &str) -> Option<(u8, usize)> {
     }
     // 3 — truncation ate into the photo name itself, leaving only a prefix of
     // it. Every suffix boundary in the stem is tried, so this holds for a
-    // localized suffix too; the longest surviving prefix wins, because a folder
-    // with `IMG_1.jpg` and `IMG_12.jpg` must not let the shorter stem claim the
-    // longer photo.
-    let mut longest: Option<usize> = None;
-    for head in suffix_boundaries(stem) {
-        if !head.is_empty()
-            && file_name.starts_with(head)
-            && longest.is_none_or(|len| head.len() > len)
-        {
-            longest = Some(head.len());
+    // localized suffix too; the longest surviving prefix wins.
+    //
+    // Only for a sidecar whose name is as long as Google lets one get: a name
+    // that short of the cap was not cut, so a prefix of it is the name of a
+    // different photo. Without this, `IMG_1.jpg`'s sidecar gave its name and
+    // date to an `IMG_12.jpg` that had none (`docs/BUGS.md` B225).
+    if stem.chars().count() + ".json".len() >= SIDECAR_NAME_CAP - 4 {
+        let mut longest: Option<usize> = None;
+        for head in suffix_boundaries(stem) {
+            if !head.is_empty()
+                && file_name.starts_with(head)
+                && longest.is_none_or(|len| head.len() > len)
+            {
+                longest = Some(head.len());
+            }
+        }
+        if let Some(len) = longest {
+            return Some((3, usize::MAX - len));
         }
     }
-    longest.map(|len| (3, usize::MAX - len))
+    // 4 — an edited copy, `IMG_1-edited.jpg` (the word is localized), which
+    // Google exports without a sidecar of its own next to `IMG_1.jpg`'s.
+    suffix_boundaries(stem)
+        .filter_map(|head| head.rsplit_once('.'))
+        .any(|(original, extension)| is_edited_copy_of(file_name, original, extension))
+        .then_some((EDITED_COPY, 0))
+}
+
+/// Whether `file_name` is `<original>-<word>.<extension>`, the name Google
+/// gives an edited copy of `<original>.<extension>`.
+fn is_edited_copy_of(file_name: &str, original: &str, extension: &str) -> bool {
+    !original.is_empty()
+        && file_name
+            .strip_prefix(original)
+            .and_then(|rest| rest.strip_prefix('-'))
+            .and_then(|rest| rest.strip_suffix(extension))
+            .and_then(|rest| rest.strip_suffix('.'))
+            .is_some_and(|word| !word.is_empty() && word.chars().all(char::is_alphabetic))
 }
 
 /// The stem plus each of its prefixes ending before a `.`, longest first — the
@@ -994,21 +1118,25 @@ mod tests {
 
     #[test]
     fn longest_prefix_wins_when_the_photo_name_itself_was_truncated() {
+        // Both sidecar names are at Google's cap, so both were cut into the
+        // photo name; the longer surviving prefix is the better claim.
+        let short = "Takeout/Google Photos/Photos from 2019/PXL_20190101_120000000.PORTRAIT_ORIGINAL_E.json";
+        let long = "Takeout/Google Photos/Photos from 2019/PXL_20190101_120000000.PORTRAIT_ORIGINAL_EXPO.json";
         let mut sidecars = HashMap::new();
         sidecar(
             &mut sidecars,
-            "Takeout/Google Photos/Photos from 2019/IMG_1.json",
+            short,
             r#"{"photoTakenTime":{"timestamp":"1"}}"#,
         );
         sidecar(
             &mut sidecars,
-            "Takeout/Google Photos/Photos from 2019/IMG_12.json",
+            long,
             r#"{"photoTakenTime":{"timestamp":"2"}}"#,
         );
         let scan = assemble(
             vec![entry(
                 0,
-                "Takeout/Google Photos/Photos from 2019/IMG_12345.jpg",
+                "Takeout/Google Photos/Photos from 2019/PXL_20190101_120000000.PORTRAIT_ORIGINAL_EXPOSURE.jpg",
                 10,
             )],
             &sidecars,
@@ -1017,6 +1145,104 @@ mod tests {
         assert_eq!(scan.photos[0].capture_time, Some(2));
     }
 
+    /// A short sidecar name was not cut, so a prefix of it names another photo:
+    /// `IMG_1.jpg`'s sidecar gave its title and date to `IMG_12.jpg`
+    /// (`docs/BUGS.md` B225).
+    #[test]
+    fn a_photo_without_a_sidecar_does_not_take_a_shorter_named_siblings() {
+        let mut sidecars = HashMap::new();
+        sidecar(
+            &mut sidecars,
+            "Takeout/Google Photos/Photos from 2019/IMG_1.jpg.supplemental-metadata.json",
+            r#"{"title":"IMG_1.jpg","photoTakenTime":{"timestamp":"1"}}"#,
+        );
+        let scan = assemble(
+            vec![
+                entry(0, "Takeout/Google Photos/Photos from 2019/IMG_1.jpg", 10),
+                entry(0, "Takeout/Google Photos/Photos from 2019/IMG_12.jpg", 10),
+            ],
+            &sidecars,
+        );
+
+        assert_eq!(scan.photos[0].capture_time, Some(1));
+        assert_eq!(scan.photos[1].name, "IMG_12.jpg");
+        assert_eq!(scan.photos[1].capture_time, None);
+    }
+
+    /// An edited copy has no sidecar of its own. It takes its original's date,
+    /// but keeps its own name rather than the original's title.
+    #[test]
+    fn an_edited_copy_takes_its_originals_date_and_keeps_its_name() {
+        let mut sidecars = HashMap::new();
+        sidecar(
+            &mut sidecars,
+            "Takeout/Google Fotos/Urlaub/IMG_2.jpg.ergänzende-Metadaten.json",
+            r#"{"title":"Holiday.jpg","photoTakenTime":{"timestamp":"7"}}"#,
+        );
+        let scan = assemble(
+            vec![
+                entry(0, "Takeout/Google Fotos/Urlaub/IMG_2.jpg", 10),
+                entry(0, "Takeout/Google Fotos/Urlaub/IMG_2-bearbeitet.jpg", 10),
+            ],
+            &sidecars,
+        );
+
+        assert_eq!(scan.photos[0].name, "Holiday.jpg");
+        assert_eq!(scan.photos[1].name, "IMG_2-bearbeitet.jpg");
+        assert_eq!(scan.photos[1].capture_time, Some(7));
+    }
+
+    /// The index looks only at the sidecars that can match, and must find the
+    /// same one that ranking every sidecar in the folder finds.
+    #[test]
+    fn the_sidecar_index_finds_what_ranking_every_sidecar_finds() {
+        let long = "A_very_long_holiday_photo_name_from_the_beach_2019";
+        let names = [
+            "IMG_1.jpg".to_string(),
+            "IMG_12.jpg".to_string(),
+            "IMG_1(1).jpg".to_string(),
+            "IMG_1-edited.jpg".to_string(),
+            "IMG_1-bearbeitet.jpg".to_string(),
+            "my.photo(2).jpg".to_string(),
+            "x(1).jpg".to_string(),
+            "Ölbild.png".to_string(),
+            "PXL_20230101_101010.mp4".to_string(),
+            format!("{long}.jpg"),
+            format!("{long}_2.jpg"),
+            "nothing.heic".to_string(),
+        ];
+        let sidecar_names = [
+            "IMG_1.jpg.supplemental-metadata.json".to_string(),
+            "IMG_1.jpg(1).supplemental-metadata.json".to_string(),
+            "IMG_12.jpg.ergänzende-Metadaten.json".to_string(),
+            "my.photo.jpg(2).json".to_string(),
+            "x.jpg(1).json".to_string(),
+            "Ölbild.png.suppl.json".to_string(),
+            "PXL_20230101_101010.mp4.JSON".to_string(),
+            format!("{}.json", &long[..44]),
+            format!("{long}.jp.json"),
+            "IMG.json".to_string(),
+            "unrelated.json".to_string(),
+        ];
+        let bodies: Vec<Vec<u8>> = (0..sidecar_names.len())
+            .map(|i| i.to_string().into_bytes())
+            .collect();
+        let in_folder: BTreeMap<String, &Vec<u8>> =
+            sidecar_names.iter().cloned().zip(bodies.iter()).collect();
+        let index = SidecarIndex::new(&in_folder);
+        for name in &names {
+            let mut every: Option<((u8, usize), &Vec<u8>)> = None;
+            for (sidecar_name, body) in &in_folder {
+                if let Some(rank) = sidecar_rank(strip_json_suffix(sidecar_name), name)
+                    && every.as_ref().is_none_or(|(current, _)| rank < *current)
+                {
+                    every = Some((rank, *body));
+                }
+            }
+            assert_eq!(find_sidecar(name, &index), every, "{name}");
+        }
+    }
+
     #[test]
     fn sidecar_title_replaces_a_mangled_on_disk_name() {
         let mut sidecars = HashMap::new();
@@ -1106,8 +1332,8 @@ mod tests {
         ));
         let file = std::fs::File::create(&path).unwrap();
         let mut zip = zip::ZipWriter::new(file);
-        let options: zip::write::FileOptions<'_, ()> =
-            zip::write::FileOptions::default().compression_method(zip::CompressionMethod::Stored);
+        let options = zip::write::SimpleFileOptions::default()
+            .compression_method(zip::CompressionMethod::Stored);
         for (name, body) in files {
             zip.start_file(*name, options).unwrap();
             zip.write_all(body).unwrap();

crates/pdfs-core/src/update.rs

@@ -0,0 +1,178 @@
+//! The opt-in check for a newer release ([`crate::config::AppConfig::update_check`]).
+//!
+//! Only the decisions live here: what GitHub's answer says, which version is
+//! newer, when to ask again, and whether a package manager already owns
+//! updates. The desktop app does the request itself.
+
+use std::path::Path;
+use std::time::Duration;
+
+/// GitHub's latest published release. Drafts and pre-releases never show up
+/// here, so a tagged release candidate does not reach anyone.
+pub const RELEASES_LATEST_API: &str =
+    "https://api.github.com/repos/narrrl/proton-drive-linux/releases/latest";
+
+/// How often the app asks, across restarts.
+pub const CHECK_INTERVAL: Duration = Duration::from_secs(24 * 60 * 60);
+
+/// Installed next to the binaries' `share/` by packages whose package manager
+/// brings new releases (COPR, the AUR, Nix). The release `.deb`, `.rpm` and
+/// `.tar.gz` do not ship it, since nothing updates them.
+pub const MANAGED_MARKER: &str = "share/proton-drive-linux/managed-updates";
+
+/// The version of the release in a `/releases/latest` answer, without the
+/// tag's `v`. `None` for an answer that does not parse or a tag that is not
+/// `X.Y.Z`, so a changed API can never claim an update.
+pub fn latest_version(body: &[u8]) -> Option<String> {
+    let json: serde_json::Value = serde_json::from_slice(body).ok()?;
+    let tag = json.get("tag_name")?.as_str()?;
+    let version = tag.strip_prefix('v').unwrap_or(tag);
+    parse(version).map(|_| version.to_owned())
+}
+
+/// Whether `version` is a later release than `current`. Anything that is not
+/// `X.Y.Z` on either side is not.
+pub fn is_newer(version: &str, current: &str) -> bool {
+    matches!((parse(version), parse(current)), (Some(v), Some(c)) if v > c)
+}
+
+/// The release page of `version` on GitHub.
+pub fn release_url(version: &str) -> String {
+    format!("https://github.com/narrrl/proton-drive-linux/releases/tag/v{version}")
+}
+
+/// `X.Y.Z` as numbers, so `3.10.0` sorts after `3.9.0`.
+fn parse(version: &str) -> Option<(u64, u64, u64)> {
+    let mut parts = version.split('.').map(|p| p.parse::<u64>().ok());
+    let triple = (parts.next()??, parts.next()??, parts.next()??);
+    parts.next().is_none().then_some(triple)
+}
+
+/// How long until the next check is due, given the last one in Unix seconds.
+/// Zero when it is due now. A clock set back past the last check counts as
+/// due, so a wrong clock cannot stop checks.
+pub fn next_check_in(last_checked: Option<i64>, now: i64) -> Duration {
+    let interval = CHECK_INTERVAL.as_secs() as i64;
+    match last_checked {
+        Some(last) if (0..interval).contains(&(now - last)) => {
+            Duration::from_secs((interval - (now - last)) as u64)
+        }
+        _ => Duration::ZERO,
+    }
+}
+
+/// Whether the binary at `exe` was installed by a package manager that updates
+/// it, which [`MANAGED_MARKER`] next to its `bin/` says.
+pub fn updates_managed(exe: &Path) -> bool {
+    exe.parent()
+        .and_then(Path::parent)
+        .is_some_and(|prefix| prefix.join(MANAGED_MARKER).exists())
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    fn latest(tag: &str) -> Vec<u8> {
+        format!(
+            r#"{{"tag_name":"{tag}","html_url":"https://github.com/narrrl/proton-drive-linux/releases/tag/{tag}","draft":false}}"#
+        )
+        .into_bytes()
+    }
+
+    #[test]
+    fn the_latest_release_is_read_without_its_v() {
+        assert_eq!(latest_version(&latest("v3.6.0")).as_deref(), Some("3.6.0"));
+        assert_eq!(latest_version(&latest("3.6.0")).as_deref(), Some("3.6.0"));
+    }
+
+    #[test]
+    fn an_answer_that_does_not_parse_has_no_version() {
+        assert_eq!(latest_version(b"not json"), None);
+        assert_eq!(latest_version(b"{}"), None);
+        assert_eq!(latest_version(br#"{"tag_name":7}"#), None);
+        assert_eq!(latest_version(&latest("nightly")), None);
+        assert_eq!(latest_version(&latest("v4.0.0-rc1")), None);
+        assert_eq!(latest_version(&latest("v4.0")), None);
+        assert_eq!(latest_version(&latest("v4.0.0.1")), None);
+    }
+
+    #[test]
+    fn only_a_later_release_is_newer() {
+        assert!(is_newer("3.6.0", "3.5.0"));
+        assert!(!is_newer("3.5.0", "3.5.0"));
+        assert!(!is_newer("3.4.1", "3.5.0"));
+        assert!(!is_newer("2.99.99", "3.0.0"));
+    }
+
+    #[test]
+    fn versions_compare_as_numbers() {
+        assert!(is_newer("3.10.0", "3.9.0"));
+        assert!(is_newer("3.5.10", "3.5.9"));
+        assert!(is_newer("4.0.0", "3.99.99"));
+    }
+
+    #[test]
+    fn a_version_that_is_not_x_y_z_is_never_newer() {
+        assert!(!is_newer("4.0.0", "3.5.0-dev"));
+        assert!(!is_newer("garbage", "3.5.0"));
+    }
+
+    #[test]
+    fn the_release_page_uses_the_tag() {
+        assert_eq!(
+            release_url("3.6.0"),
+            "https://github.com/narrrl/proton-drive-linux/releases/tag/v3.6.0"
+        );
+    }
+
+    #[test]
+    fn a_check_is_due_once_a_day() {
+        let day = CHECK_INTERVAL.as_secs() as i64;
+        assert_eq!(next_check_in(None, 1_000), Duration::ZERO);
+        assert_eq!(next_check_in(Some(1_000), 1_000), CHECK_INTERVAL);
+        assert_eq!(
+            next_check_in(Some(1_000), 1_000 + day - 1),
+            Duration::from_secs(1)
+        );
+        assert_eq!(next_check_in(Some(1_000), 1_000 + day), Duration::ZERO);
+        assert_eq!(
+            next_check_in(Some(1_000), 999),
+            Duration::ZERO,
+            "a clock set back must not stop checks"
+        );
+    }
+
+    /// A unique temp directory removed on drop; avoids a dev-dependency, as in
+    /// [`crate::syncignore`]'s tests.
+    struct TempDir(std::path::PathBuf);
+    impl TempDir {
+        fn new() -> Self {
+            use std::sync::atomic::{AtomicU64, Ordering};
+            static N: AtomicU64 = AtomicU64::new(0);
+            let p = std::env::temp_dir().join(format!(
+                "pdfs-update-{}-{}",
+                std::process::id(),
+                N.fetch_add(1, Ordering::Relaxed)
+            ));
+            std::fs::create_dir_all(&p).unwrap();
+            TempDir(p)
+        }
+    }
+    impl Drop for TempDir {
+        fn drop(&mut self) {
+            let _ = std::fs::remove_dir_all(&self.0);
+        }
+    }
+
+    #[test]
+    fn the_marker_next_to_bin_means_a_package_manager_updates() {
+        let prefix = TempDir::new();
+        let exe = prefix.0.join("bin/pdfs-app");
+        assert!(!updates_managed(&exe));
+        let marker = prefix.0.join(MANAGED_MARKER);
+        std::fs::create_dir_all(marker.parent().unwrap()).unwrap();
+        std::fs::write(&marker, "").unwrap();
+        assert!(updates_managed(&exe));
+    }
+}

crates/pdfs-fuse/src/background.rs

@@ -2,6 +2,7 @@
 
 use super::*;
 use crate::shutdown::Shutdown;
+use pdfs_core::error::session_revoked;
 
 /// Drop `uid` from one mount's tree and tell that mount's kernel session the
 /// entry is gone. Shared by the trash and delete paths, which differ only in
@@ -402,6 +403,12 @@ pub(super) async fn run_event_sync(
                         }
                         break Some(c.clone());
                     }
+                    // Refused for good: retrying would be refused the same way
+                    // for the life of the daemon. The next login restarts it.
+                    Err(e) if session_revoked(&e) => {
+                        core.mark_session_expired("seed event cursor", &e);
+                        return;
+                    }
                     Err(e) => {
                         warn!(error = %e, ?delay, "seed event cursor failed; retrying");
                         tokio::time::sleep(delay).await;
@@ -502,6 +509,10 @@ pub(super) async fn run_photos_event_sync(core: Core) {
                 debug!("no photos volume; photo event sync not started");
                 return;
             }
+            Err(error) if session_revoked(&error) => {
+                core.mark_session_expired("read the photos root", &error);
+                return;
+            }
             Err(error) => {
                 warn!(%error, "reading the photos root failed; retrying");
                 tokio::time::sleep(ONLINE_PROBE_MAX).await;
@@ -710,18 +721,26 @@ fn scan_local_once(
 
     // The walk has no idea how many files it will find, so the job counts what it
     // has seen and stays indeterminate.
-    let job = transfers.begin_job("Indexing this computer");
+    let job = transfers.begin_background_job("Indexing this computer");
     job.detail("Scanning your files");
+    let mut failed = false;
     let walked = localindex::scan(&[home], &excludes, |batch| {
         if let Err(e) = db.local_upsert_batch(generation, &batch) {
             warn!(error = %e, "local index: batch write failed");
+            failed = true;
         }
     });
 
-    // Prune what this scan did not see and rebuild the FTS index over the rest,
-    // even if some batches failed — a partial index still beats none.
+    // Prune what this scan did not see, unless it did not see everything:
+    // a path it never reached, or one whose batch failed to write, is not a
+    // path that is gone (`docs/BUGS.md` B217).
     job.detail("Building the search index");
-    match db.local_finish_scan(generation, now_secs()) {
+    let finished = if failed || walked >= localindex::MAX_ENTRIES {
+        db.local_finish_partial_scan(now_secs())
+    } else {
+        db.local_finish_scan(generation, now_secs())
+    };
+    match finished {
         Ok(indexed) => info!(
             walked,
             indexed,

crates/pdfs-fuse/src/control.rs

@@ -29,6 +29,17 @@ use super::{Core, count_noun, human_bytes, human_duration, parse_uid};
 
 const MAX_CONTROL_REQUEST_BYTES: u64 = 1024 * 1024;
 const CONTROL_READ_TIMEOUT: Duration = Duration::from_secs(10);
+/// Answer a [`CtlRequest::FolderSize`].
+fn folder_size_reply(size: CoreResult<proton_drive_rs::FolderSize>) -> CtlResponse {
+    match size {
+        Ok(size) => CtlResponse::FolderSize {
+            size: size.size,
+            items: size.descendants,
+        },
+        Err(e) => CtlResponse::error(e),
+    }
+}
+
 /// Answer a [`CtlRequest::StopSharing`]: log it, and turn a partial removal
 /// into an error that names what is still shared.
 fn stop_sharing_reply(
@@ -99,7 +110,7 @@ struct ControlHandlerPermit;
 impl ControlHandlerPermit {
     fn acquire() -> Option<Self> {
         ACTIVE_CONTROL_HANDLERS
-            .fetch_update(Ordering::AcqRel, Ordering::Acquire, |active| {
+            .try_update(Ordering::AcqRel, Ordering::Acquire, |active| {
                 (active < MAX_CONTROL_HANDLERS).then_some(active + 1)
             })
             .ok()
@@ -334,6 +345,9 @@ pub(crate) fn status_response(core: &Core, username: &str, mountpoint: &Path) ->
         budget: core.cache.budget(),
         pins,
         online: core.online.load(Ordering::Relaxed),
+        session_expired: core.session_expired(),
+        tokens_unsaved: pdfs_core::auth::tokens_unsaved(),
+        version: env!("CARGO_PKG_VERSION").to_string(),
         pending_uploads: queued.uploads.max(0) as u64 + landing,
         pending_changes: queued.changes.max(0) as u64,
     }
@@ -369,11 +383,12 @@ fn touched_topics(request: &CtlRequest) -> &'static [Topic] {
             RefreshScope::Photos { .. } => &[],
         },
         R::RenameDevice { .. } | R::DeleteDevice { .. } => &[Topic::Devices],
-        R::AdoptDevice { .. } => &[Topic::Devices, Topic::Locations],
+        R::AdoptDevice { .. } | R::MigrateDevice { .. } => &[Topic::Devices, Topic::Locations],
         R::AddSyncFolder { .. }
         | R::RemoveSyncFolder { .. }
         | R::SetSyncFolderMode { .. }
         | R::SetSyncFolderPaused { .. }
+        | R::ResetSyncFolder { .. }
         | R::RestoreSyncFolders { .. }
         | R::RestoreDeviceFolders { .. } => &[Topic::Locations, Topic::Devices],
         R::RetryPendingOp { .. } => &[Topic::Queue],
@@ -389,6 +404,8 @@ fn touched_topics(request: &CtlRequest) -> &'static [Topic] {
         | R::CreatePublicLinkByUid { .. }
         | R::RemovePublicLink { .. }
         | R::RemovePublicLinkByUid { .. }
+        | R::UpdatePublicLink { .. }
+        | R::UpdatePublicLinkByUid { .. }
         | R::StopSharing { .. }
         | R::StopSharingByUid { .. } => &[Topic::Shares, Topic::Files],
         R::LeaveShared { .. }
@@ -908,10 +925,22 @@ fn handle_control_conn(core: &Core, username: &str, mountpoint: &Path, stream: U
                 ))),
                 Ok((file, len)) => {
                     let photos = core.photos();
+                    // Unless the caller knows better: the photo's own EXIF,
+                    // then the file's modification time, which a copy resets.
+                    let capture_time = capture_time.or_else(|| {
+                        let path = Path::new(&source_path);
+                        pdfs_core::exiftime::capture_time_of(path).or_else(|| {
+                            let modified =
+                                std::fs::metadata(path).and_then(|m| m.modified()).ok()?;
+                            let since = modified.duration_since(std::time::UNIX_EPOCH).ok()?;
+                            Some(since.as_secs() as i64)
+                        })
+                    });
                     let metadata = proton_drive_rs::PhotoUploadMetadata {
                         capture_time,
                         ..Default::default()
                     };
+                    let thumbnails = core.upload_thumbnails(Path::new(&source_path), &name);
                     let guard =
                         core.transfers
                             .begin(name.clone(), "", TransferDirection::Upload, len);
@@ -921,7 +950,7 @@ fn handle_control_conn(core: &Core, username: &str, mountpoint: &Path, stream: U
                         &media_type,
                         reader,
                         len as i64,
-                        Vec::new(),
+                        thumbnails,
                         metadata,
                         false,
                     )) {
@@ -938,6 +967,9 @@ fn handle_control_conn(core: &Core, username: &str, mountpoint: &Path, stream: U
                             }
                         }
                         Err(e) => {
+                            // The reply goes to the app's toast only; without
+                            // this the journal shows a failure and no reason.
+                            warn!(error = %e, "photo upload failed");
                             CtlResponse::error(CoreError::from_api(&e, "upload photo failed"))
                         }
                     }
@@ -1045,6 +1077,36 @@ fn handle_control_conn(core: &Core, username: &str, mountpoint: &Path, stream: U
                 (Err(e), _) | (_, Err(e)) => CtlResponse::error(e),
             }
         }
+        Ok(CtlRequest::Copy { path, new_parent }) => {
+            match (
+                rel_to_mount(mountpoint, &path),
+                rel_to_mount(mountpoint, &new_parent),
+            ) {
+                (Ok(rel), Ok(parent_rel)) => match core.copy_to(&rel, &parent_rel) {
+                    Ok(name) => {
+                        let dest = if new_parent.is_empty() {
+                            "My files".to_string()
+                        } else {
+                            new_parent.clone()
+                        };
+                        core.log_activity(ActivityKind::Copy, &name, format!("to {dest}"), true);
+                        CtlResponse::Ok {
+                            message: format!("copied to {name}"),
+                        }
+                    }
+                    Err(e) => {
+                        core.log_activity(ActivityKind::Copy, &path, &e, false);
+                        CtlResponse::error(e)
+                    }
+                },
+                (Err(e), _) | (_, Err(e)) => CtlResponse::error(e),
+            }
+        }
+        Ok(CtlRequest::FolderSize { path }) => match rel_to_mount(mountpoint, &path) {
+            Ok(rel) => folder_size_reply(core.folder_size(&rel)),
+            Err(e) => CtlResponse::error(e),
+        },
+        Ok(CtlRequest::FolderSizeByUid { uid }) => folder_size_reply(core.folder_size_by_uid(&uid)),
         Ok(CtlRequest::Delete { path }) => match route_node(core, mountpoint, &path) {
             Ok((core, rel)) => match core.delete(&rel) {
                 Ok(name) => {
@@ -1297,6 +1359,10 @@ fn handle_control_conn(core: &Core, username: &str, mountpoint: &Path, stream: U
             Ok(message) => CtlResponse::Ok { message },
             Err(e) => CtlResponse::error(e),
         },
+        Ok(CtlRequest::MigrateDevice { uid }) => match core.migrate_device(&uid) {
+            Ok(message) => CtlResponse::Ok { message },
+            Err(e) => CtlResponse::error(e),
+        },
         Ok(CtlRequest::AddSyncFolder { local_path }) => {
             // Registering the device and uploading a folder tree far outlasts the
             // socket read timeout, so ack immediately and work on a background
@@ -1367,6 +1433,13 @@ fn handle_control_conn(core: &Core, username: &str, mountpoint: &Path, stream: U
                 Err(e) => CtlResponse::error(e),
             }
         }
+        Ok(CtlRequest::ResetSyncFolder { id }) => match core.reset_sync_folder(id) {
+            Ok(message) => {
+                core.log_activity(ActivityKind::Sync, &message, "", true);
+                CtlResponse::Ok { message }
+            }
+            Err(e) => CtlResponse::error(e),
+        },
         Ok(CtlRequest::SyncNow { id }) => {
             core.sync_now(id);
             CtlResponse::Ok {
@@ -1453,9 +1526,17 @@ fn handle_control_conn(core: &Core, username: &str, mountpoint: &Path, stream: U
             let core = core.clone();
             std::thread::spawn(move || {
                 match core.restore_sync_folders(&items, device.as_deref()) {
-                    Ok(message) => {
+                    Ok(outcome) => {
                         core.touch_profile();
-                        core.log_activity(ActivityKind::Download, &message, "", true);
+                        if !outcome.complete() {
+                            warn!(skipped = ?outcome.skipped, "restore skipped folders");
+                        }
+                        core.log_activity(
+                            ActivityKind::Download,
+                            outcome.summary(),
+                            outcome.skipped.join("; "),
+                            outcome.complete(),
+                        );
                     }
                     Err(e) => {
                         warn!(error = %e, "restore failed");
@@ -1608,6 +1689,31 @@ fn handle_control_conn(core: &Core, username: &str, mountpoint: &Path, stream: U
                 CtlResponse::error(e)
             }
         },
+        Ok(CtlRequest::UpdatePublicLink {
+            path,
+            id,
+            role,
+            password,
+            expires,
+        }) => match rel_to_mount(mountpoint, &path) {
+            Ok(rel) => {
+                match core.update_public_link(&rel, &id, role.as_deref(), password, expires) {
+                    Ok(link) => CtlResponse::PublicLink { link },
+                    Err(e) => CtlResponse::error(e),
+                }
+            }
+            Err(e) => CtlResponse::error(e),
+        },
+        Ok(CtlRequest::UpdatePublicLinkByUid {
+            uid,
+            id,
+            role,
+            password,
+            expires,
+        }) => match core.update_public_link_by_uid(&uid, &id, role.as_deref(), password, expires) {
+            Ok(link) => CtlResponse::PublicLink { link },
+            Err(e) => CtlResponse::error(e),
+        },
         Ok(CtlRequest::RemovePublicLink { path, id }) => match rel_to_mount(mountpoint, &path) {
             Ok(rel) => match core.remove_public_link(&rel, &id) {
                 Ok(()) => {

crates/pdfs-fuse/src/devices.rs

@@ -19,6 +19,7 @@ use pdfs_core::control::{
 };
 use pdfs_core::db::{StoredDevice, StoredSyncFolder};
 use pdfs_core::mounts::MountMode;
+use pdfs_core::profile::PROFILE_DIR_NAME;
 use pdfs_core::{CoreError, CoreResult};
 use proton_drive_rs::proton_sdk::ids::{DeviceUid, NodeUid};
 use proton_drive_rs::{DeviceType, Node};
@@ -104,6 +105,15 @@ pub(crate) fn adopted_device_uid() -> Option<String> {
     (!uid.is_empty()).then_some(uid)
 }
 
+/// The paths no sync root may overlap, with the mountpoint as the config says
+/// now.
+pub(crate) fn sync_root_reserved() -> pdfs_core::syncroot::Reserved {
+    let config = pdfs_core::config::AppDirs::new()
+        .map(|dirs| dirs.load_config())
+        .unwrap_or_default();
+    pdfs_core::syncroot::Reserved::current(&config)
+}
+
 /// Pin (or, with `None`, unpin) the adopted device uid in `config.json`.
 pub(crate) fn set_adopted_device_uid(uid: Option<&str>) -> CoreResult<()> {
     let dirs = pdfs_core::config::AppDirs::new()
@@ -114,6 +124,22 @@ pub(crate) fn set_adopted_device_uid(uid: Option<&str>) -> CoreResult<()> {
         .map_err(|e| CoreError::internal(format!("write config: {e}")))
 }
 
+/// The name a folder moved in from `device` takes when `name` is already
+/// taken under this device's root, or `None` when it can keep its own.
+fn migrated_name(name: &str, device: &str, taken: &[String]) -> Option<String> {
+    let free = |candidate: &str| !taken.iter().any(|t| t == candidate);
+    if free(name) {
+        return None;
+    }
+    let base = format!("{name} ({device})");
+    if free(&base) {
+        return Some(base);
+    }
+    (2..)
+        .map(|n| format!("{base} {n}"))
+        .find(|candidate| free(candidate))
+}
+
 impl Core {
     // ---- devices ----------------------------------------------------------
 
@@ -140,7 +166,7 @@ impl Core {
     pub(crate) fn list_devices(&self) -> CoreResult<Vec<DeviceInfo>> {
         let devices = self
             .rt
-            .block_on(self.client.enumerate_devices())
+            .block_on(self.drive.enumerate_devices())
             .map_err(|e| CoreError::from_api(&e, "list devices"))?;
         // No cached device row yet means this machine syncs nothing, so none of
         // the listed devices is ours.
@@ -197,7 +223,7 @@ impl Core {
         };
         let remote = self
             .rt
-            .block_on(self.client.enumerate_devices())
+            .block_on(self.drive.enumerate_devices())
             .map_err(|e| CoreError::from_api(&e, "enumerate devices"))?;
         let dev = remote
             .into_iter()
@@ -240,7 +266,7 @@ impl Core {
         };
         let remote = self
             .rt
-            .block_on(self.client.enumerate_devices())
+            .block_on(self.drive.enumerate_devices())
             .map_err(|e| CoreError::from_api(&e, "enumerate devices"))?;
         let d = remote
             .into_iter()
@@ -260,6 +286,107 @@ impl Core {
         })
     }
 
+    /// Move every folder another device backs up into this machine's own
+    /// device, so this machine carries on backing them up as itself. The other
+    /// device stays registered, without those folders.
+    ///
+    /// Device roots all live on the main volume, so each folder is one
+    /// server-side move: nothing is downloaded or uploaded, and no quota is
+    /// used twice. A folder whose name is taken here keeps its content under
+    /// "<name> (<device>)". A failed folder does not stop the others, and a
+    /// second run picks up whatever is still left on the other device.
+    ///
+    /// Nothing is synced to this disk here. The moved folders are now this
+    /// device's, so the ordinary restore offers them. Only folders that were
+    /// already synced here from the other device are touched: their uid
+    /// survives the move but their share does not.
+    pub(crate) fn migrate_device(&self, uid: &str) -> CoreResult<String> {
+        let source = self.restore_source(Some(uid))?;
+        let target = self.ensure_device()?;
+        if source.uid == target.uid {
+            return Err(CoreError::invalid(format!(
+                "{} is this computer's own device",
+                source.name
+            )));
+        }
+        let bad_root = |d: &StoredDevice| {
+            parse_uid(&d.root_uid)
+                .ok_or_else(|| CoreError::internal(format!("bad device root uid: {}", d.root_uid)))
+        };
+        let (source_root, target_root) = (bad_root(&source)?, bad_root(&target)?);
+        if source_root.volume_id != target_root.volume_id {
+            return Err(CoreError::invalid(
+                "the two devices are on different Proton Drive volumes; copy it instead",
+            ));
+        }
+
+        let mut taken: Vec<String> = self
+            .device_root_nodes(&target_root)?
+            .into_iter()
+            .filter(|n| !n.trashed)
+            .map(|n| n.name)
+            .collect();
+        let synced = self
+            .db
+            .sync_folder_list()
+            .map_err(|e| CoreError::internal(format!("db: {e:?}")))?;
+
+        let mut moved = 0usize;
+        let mut renamed: Vec<String> = Vec::new();
+        let mut left: Vec<String> = Vec::new();
+        let mut failed: Vec<String> = Vec::new();
+        for node in self.device_root_nodes(&source_root)? {
+            if node.trashed || node.name == PROFILE_DIR_NAME {
+                continue;
+            }
+            // A device root only ever holds folders (B68); anything else was
+            // put there by hand and is left for the user to deal with.
+            if !node.is_folder() {
+                left.push(node.name);
+                continue;
+            }
+            let new_name = migrated_name(&node.name, &source.name, &taken);
+            if let Err(e) = self.move_rename_remote(&node.uid, &target_root, new_name.as_deref()) {
+                warn!(name = %node.name, error = %e, "migrate: could not move folder");
+                failed.push(format!("{}: {e}", node.name));
+                continue;
+            }
+            let landed = new_name.clone().unwrap_or_else(|| node.name.clone());
+            if new_name.is_some() {
+                renamed.push(format!("{} -> {landed}", node.name));
+            }
+            taken.push(landed);
+            moved += 1;
+
+            let uid = node.uid.to_string();
+            for folder in synced.iter().filter(|f| f.remote_uid == uid) {
+                if let Err(e) = self.db.sync_folder_set_share(folder.id, &target.share_id) {
+                    warn!(id = folder.id, error = ?e, "migrate: could not re-point sync folder");
+                }
+                self.sync_now(Some(folder.id));
+            }
+        }
+        self.invalidate_children_of(&source_root);
+        self.invalidate_children_of(&target_root);
+
+        let mut message = format!("moved {moved} folder(s) from {}", source.name);
+        if !renamed.is_empty() {
+            message.push_str(&format!("; renamed: {}", renamed.join(", ")));
+        }
+        if !left.is_empty() {
+            message.push_str(&format!("; left behind: {}", left.join(", ")));
+        }
+        if !failed.is_empty() {
+            message.push_str(&format!("; failed: {}", failed.join(", ")));
+        }
+        info!(from = %source.name, to = %target.name, moved, failed = failed.len(),
+            "device migrated");
+        if moved == 0 && !failed.is_empty() {
+            return Err(CoreError::conflict(message));
+        }
+        Ok(message)
+    }
+
     // ---- device folder sync -------------------------
 
     /// Auto-register (or recover) this machine as a Proton Drive Device, caching
@@ -277,7 +404,7 @@ impl Core {
         // any cached record, and recover an existing device by name.
         let remote = self
             .rt
-            .block_on(self.client.enumerate_devices())
+            .block_on(self.drive.enumerate_devices())
             .map_err(|e| CoreError::from_api(&e, "enumerate devices"))?;
 
         // An adopted uid is an explicit instruction, so it outranks everything
@@ -336,7 +463,7 @@ impl Core {
             None => {
                 let d = self
                     .rt
-                    .block_on(self.client.create_device(&name, DeviceType::Linux))
+                    .block_on(self.drive.create_device(&name, DeviceType::Linux))
                     .map_err(|e| CoreError::from_api(&e, "create device"))?;
                 StoredDevice {
                     uid: d.uid.to_string(),
@@ -360,21 +487,25 @@ impl Core {
         root_uid: &NodeUid,
         name: &str,
     ) -> CoreResult<Option<NodeUid>> {
+        Ok(self
+            .device_root_nodes(root_uid)?
+            .into_iter()
+            .find(|n| n.is_folder() && !n.trashed && n.name == name)
+            .map(|n| n.uid))
+    }
+
+    /// Everything directly under a device root, trashed nodes included.
+    fn device_root_nodes(&self, root_uid: &NodeUid) -> CoreResult<Vec<Node>> {
         let uids = self
             .rt
             .block_on(self.drive.enumerate_folder_children_node_uids(root_uid))
             .map_err(|e| CoreError::from_api(&e, "list device root"))?;
         if uids.is_empty() {
-            return Ok(None);
+            return Ok(Vec::new());
         }
-        let nodes = self
-            .rt
+        self.rt
             .block_on(self.drive.enumerate_nodes(&uids))
-            .map_err(|e| CoreError::from_api(&e, "resolve device root children"))?;
-        Ok(nodes
-            .into_iter()
-            .find(|n| n.is_folder() && !n.trashed && n.name == name)
-            .map(|n| n.uid))
+            .map_err(|e| CoreError::from_api(&e, "resolve device root children"))
     }
 
     /// Add a local folder to this device's sync set: register the device if
@@ -395,18 +526,20 @@ impl Core {
             .map_err(|e| CoreError::internal(format!("canonicalize {}: {e}", local.display())))?;
         let local_str = local.to_string_lossy().to_string();
 
-        // Reject duplicates up front for a clear error (UNIQUE would also catch it).
-        if self
+        // `/`, the home folder, the mount, this app's own data, and a folder
+        // inside or around another root are refused (`syncroot::problem`). A
+        // duplicate is one of those, refused here for a clear error before
+        // the UNIQUE constraint would catch it.
+        let others = self
             .db
             .sync_folder_list()
             .map_err(|e| CoreError::internal(format!("db: {e:?}")))?
             .iter()
-            .any(|f| f.local_path == local_str)
-        {
-            return Err(CoreError::invalid(format!(
-                "{} is already synced",
-                local.display()
-            )));
+            .map(|f| PathBuf::from(&f.local_path))
+            .collect::<Vec<_>>();
+        let reserved = sync_root_reserved();
+        if let Some(problem) = pdfs_core::syncroot::problem(&local, &others, &reserved) {
+            return Err(CoreError::invalid(problem));
         }
 
         let name = local
@@ -535,12 +668,16 @@ impl Core {
                     } else {
                         p.total.max(p.done) as u64
                     },
+                    // Most passes find nothing; only one that queues work is
+                    // the drive syncing.
+                    background: true,
                 },
                 SyncPhase::Applying => JobItem {
                     title: format!("Syncing {folder}"),
                     detail: p.current.clone(),
                     done: p.done as u64,
                     total: p.total.max(p.done) as u64,
+                    background: false,
                 },
             });
         }
@@ -842,6 +979,29 @@ impl Core {
                 if folder.state != "idle" {
                     return Err(SwitchBlocked::NotNow);
                 }
+                // `idle` only says the last pass applied everything it tried.
+                // It never tries an ignored path, a symlink or a folder it
+                // cannot read, it defers a file open for writing, and a file can
+                // change after it ends. The eviction below deletes all of those
+                // for good, so it waits until nothing here is missing from Drive
+                // (B198).
+                let baseline = self
+                    .db
+                    .sync_entries(id)
+                    .map_err(|e| SwitchBlocked::Failed(format!("db: {e:?}")))?;
+                let rules = self.ignore_rules(&local);
+                // Emptied before any pass saw it, the folder is still `idle`, and
+                // the check below would refuse the switch for good. The push pass
+                // of a queued switch forgets those paths instead (`docs/BUGS.md`
+                // B255).
+                if sync::mirror_tree_gone(&local, &baseline, &rules) {
+                    return Err(SwitchBlocked::NotNow);
+                }
+                if let Some(reason) = sync::mirror_tree_unsynced(&local, &baseline, &rules) {
+                    return Err(SwitchBlocked::Failed(format!(
+                        "going online-only would delete what is only on this computer: {reason}"
+                    )));
+                }
                 let root_uid = parse_uid(&folder.remote_uid).ok_or_else(|| {
                     SwitchBlocked::Failed(format!("bad remote uid: {}", folder.remote_uid))
                 })?;
@@ -926,6 +1086,50 @@ impl Core {
         }
     }
 
+    /// Forget what a mirror folder synced before, so its next pass compares the
+    /// two sides as on the first sync: what one side has alone is copied to the
+    /// other, and a file that differs is kept twice as a conflict. Nothing is
+    /// deleted on either side.
+    ///
+    /// This is the way out for a folder whose passes refuse to run because its
+    /// whole local copy, or its whole copy on Drive, is gone (#46). The baseline
+    /// is what makes that read as "delete everything", and it is what this
+    /// drops. A queued switch to on-demand is dropped with it: the push pass
+    /// that switch runs reads an unrecorded local file as new and would upload
+    /// a second copy of every file Drive already has.
+    pub(crate) fn reset_sync_folder(&self, id: i64) -> CoreResult<String> {
+        let lock = self.sync_lock(id);
+        let Some(_guard) = lock.try_lock() else {
+            return Err(CoreError::conflict(
+                "this folder is syncing; try again when the pass ends",
+            ));
+        };
+        let folder = self
+            .db
+            .sync_folder_get(id)
+            .map_err(|e| CoreError::internal(format!("db: {e:?}")))?
+            .ok_or_else(|| CoreError::not_found(format!("no synced folder with id {id}")))?;
+        if folder.mode != "mirror" {
+            return Err(CoreError::invalid(
+                "an online-only folder keeps nothing on this computer to sync from scratch",
+            ));
+        }
+        self.db
+            .sync_entries_clear(id)
+            .map_err(|e| CoreError::internal(format!("db: {e:?}")))?;
+        if folder.pending_mode.as_deref() == Some("ondemand") {
+            self.db
+                .sync_folder_set_pending_mode(id, None)
+                .map_err(|e| CoreError::internal(format!("db: {e:?}")))?;
+        }
+        let _ = self.sync_tx.send(sync::SyncMsg::Reconcile(id));
+        info!(id, path = %folder.local_path, "sync folder reset");
+        Ok(format!(
+            "{} will sync from scratch",
+            base_name(&folder.local_path)
+        ))
+    }
+
     /// Spawn a secondary FUSE session rooted at `root` over `local` from a
     /// [`Core::fork_state`] sibling. Clears any stale kernel mount first (a crashed run can leave
     /// one, which would fail the fresh mount with EBUSY).
@@ -1107,10 +1311,38 @@ mod tests {
     use pdfs_core::db::StoredSyncFolder;
 
     use super::{
-        ApplicableMountMode, commit_after_teardown, pending_intent_matches,
+        ApplicableMountMode, commit_after_teardown, migrated_name, pending_intent_matches,
         restore_snapshot_matches, select_mode_transition,
     };
 
+    #[test]
+    fn migrated_folder_keeps_its_name_when_it_is_free() {
+        let taken = vec!["Pictures".to_string()];
+        assert_eq!(migrated_name("Documents", "DESKTOP-1", &taken), None);
+    }
+
+    #[test]
+    fn migrated_folder_is_named_after_its_device_on_a_clash() {
+        let taken = vec!["Documents".to_string()];
+        assert_eq!(
+            migrated_name("Documents", "DESKTOP-1", &taken).as_deref(),
+            Some("Documents (DESKTOP-1)")
+        );
+    }
+
+    #[test]
+    fn migrated_folder_is_numbered_when_the_device_name_is_taken_too() {
+        let taken = vec![
+            "Documents".to_string(),
+            "Documents (DESKTOP-1)".to_string(),
+            "Documents (DESKTOP-1) 2".to_string(),
+        ];
+        assert_eq!(
+            migrated_name("Documents", "DESKTOP-1", &taken).as_deref(),
+            Some("Documents (DESKTOP-1) 3")
+        );
+    }
+
     #[test]
     fn unknown_mode_cannot_select_a_destructive_transition() {
         let mut unmounts = 0;

crates/pdfs-fuse/src/diagnostics.rs

@@ -163,6 +163,7 @@ impl Core {
             control_handlers: super::control::active_handlers(),
             control_handler_limit: super::control::handler_limit(),
             pending_ops: self.pending_ops_quickly(),
+            sync: Some(self.sync_engine.report()),
         }
     }
 

crates/pdfs-fuse/src/drain.rs

@@ -347,17 +347,7 @@ impl Core {
                         // its writer has to be noticed.
                         self.sweep_parked_creates();
                     }
-                    // Paused, nothing due changes that: sleep until a resume
-                    // wakes the worker (or the idle poll notices a timed pause
-                    // ran out), not until the next op falls due — that is
-                    // "now" for everything already queued.
-                    if paused {
-                        self.wait_for_drain_work();
-                        continue;
-                    }
-                    // A debounced or backed-off op may be waiting: sleep only
-                    // until it becomes due rather than the full idle-poll.
-                    self.wait_for_drain_work_or_due();
+                    self.wait_for_drain_work_or_due(online && !paused);
                     continue;
                 }
             };
@@ -399,13 +389,7 @@ impl Core {
                 // A name a change of ours is about to free is a wait, not a
                 // failure: the trash or rename holding it lands in moments.
                 let held = waits_for_name(e.as_ref());
-                let backoff = if held {
-                    DRAIN_BACKOFF_MIN
-                } else {
-                    DRAIN_BACKOFF_MIN
-                        .saturating_mul(1u32 << attempts.min(6))
-                        .min(DRAIN_BACKOFF_MAX)
-                };
+                let backoff = drain_backoff(attempts, held, op.id);
                 warn!(uid = %op.uid, attempts, error = %err_str, "pending upload failed; will retry");
                 if let Err(e) = self.db.record_attempt_failure(
                     op.id,
@@ -732,14 +716,16 @@ impl Core {
     /// Like [`wait_for_drain_work`](Self::wait_for_drain_work), but first
     /// checks whether a debounced or backed-off op is due before the idle-poll
     /// ceiling. A 2-second debounce must not sleep 30 seconds.
-    fn wait_for_drain_work_or_due(&self) {
-        let timeout = match self.db.earliest_due_at() {
-            Ok(Some(ts)) => {
-                let remaining = (ts - now_millis()).max(0) as u64;
-                Duration::from_millis(remaining).min(DRAIN_IDLE_POLL)
-            }
-            _ => DRAIN_IDLE_POLL,
+    ///
+    /// `claiming` is false while the worker claims nothing (offline or
+    /// paused); see [`idle_wait`].
+    fn wait_for_drain_work_or_due(&self, claiming: bool) {
+        let earliest = if claiming {
+            self.db.earliest_due_at().ok().flatten()
+        } else {
+            None
         };
+        let timeout = idle_wait(claiming, earliest, now_millis());
         sleep_for_drain_work(&self.drain_wake, || self.shutdown.is_stopping(), timeout);
     }
 
@@ -1126,7 +1112,7 @@ impl Core {
             _ => None,
         };
         let sent = self.create_sent_digests(op.id, current);
-        Ok(adoptable(is_dir, &twin, op.created_at, &sent).then_some(twin.uid))
+        Ok(adoptable(is_dir, &twin, self.first_sent(op), &sent).then_some(twin.uid))
     }
 
     /// Record the name the remote actually gave a node, after a conflict forced
@@ -1295,6 +1281,13 @@ impl Core {
             sent: (&sent.0, &sent.1),
             landed: (&home.to_string(), &name),
         };
+        // Counted from the op's retirement until the bytes are cached and the
+        // tree has the real uid, as an upload is. Uncounted, the queue read
+        // empty while that still ran: a delete in between took an open file
+        // for closed and dropped what its handle reads, and a script that
+        // waited for an empty queue read the file before it was cached
+        // (`docs/BUGS.md` B257).
+        let _landing = LandingUpload::begin(&self.landing_uploads);
         let newer = match self.retire_create(op, uploaded, &landing, &local, &real)? {
             CreateRetired::Withdrawn { trash } => {
                 return self.trash_withdrawn_create(op, trash, &local, &real, &name);
@@ -1521,8 +1514,10 @@ impl Core {
             .as_deref()
             .is_some_and(|sha| holds_bytes(&twin, sha));
         let sent = self.create_sent_digests(op.id, current);
-        Ok(adoptable(op.kind == OP_MKDIR, &twin, op.created_at, &sent)
-            .then_some((twin.uid, holds_blob)))
+        Ok(
+            adoptable(op.kind == OP_MKDIR, &twin, self.first_sent(op), &sent)
+                .then_some((twin.uid, holds_blob)),
+        )
     }
 
     /// The SHA-1s of the bytes queued create `id` may have made its file with:
@@ -1537,6 +1532,22 @@ impl Core {
         sent
     }
 
+    /// When create `op` first went out, which is the earliest a node its lost
+    /// answer left can have been made. An op queued offline may wait for days
+    /// before that; measured from when it was queued, the adoption window let
+    /// it take a node another device made in the meantime. Ops sent before the
+    /// time was recorded fall back to when they were queued.
+    fn first_sent(&self, op: &PendingOp) -> i64 {
+        match self.db.create_first_sent(op.id) {
+            Ok(Some(at)) => at.max(op.created_at),
+            Ok(None) => op.created_at,
+            Err(e) => {
+                warn!(id = op.id, error = %e, "reading when a queued create was sent failed");
+                op.created_at
+            }
+        }
+    }
+
     /// Make one queued `create`/`mkdir` real under a given name, and hand back
     /// the API's own error so the caller can tell a name clash from a failure.
     ///
@@ -1549,7 +1560,7 @@ impl Core {
         name: &str,
     ) -> Result<NodeUid, Box<dyn std::error::Error>> {
         self.db
-            .note_create_target(op.id, &parent.to_string(), name)?;
+            .note_create_target(op.id, &parent.to_string(), name, now_millis())?;
         match op.kind == OP_MKDIR {
             true => Ok(self.block_on_bounded(self.drive.create_folder(
                 parent,
@@ -1594,7 +1605,7 @@ impl Core {
             .begin(name, op.uid.clone(), TransferDirection::Upload, meta.len);
         let reader = CountingReader::new(File::open(blob)?, &guard);
         let uid = self.block_on_within(
-            link::upload_deadline(meta.len),
+            link::upload_deadline(meta.len, self.transfers.upload_cap()),
             self.drive.upload_file_from(
                 parent,
                 name,
@@ -1991,7 +2002,7 @@ impl Core {
                 .begin(&alt, meta.uid.clone(), TransferDirection::Upload, meta.len);
         let reader = CountingReader::new(File::open(blob)?, &guard);
         self.block_on_within(
-            link::upload_deadline(meta.len),
+            link::upload_deadline(meta.len, self.transfers.upload_cap()),
             self.drive.upload_file_from(
                 &parent,
                 &alt,
@@ -2244,7 +2255,7 @@ impl Core {
             .clone()
             .ok_or("pending op has no staged blob")?;
         let blob = PathBuf::from(blob);
-        let meta: StagedWrite = serde_json::from_str(op.meta_json.as_deref().unwrap_or(""))?;
+        let mut meta: StagedWrite = serde_json::from_str(op.meta_json.as_deref().unwrap_or(""))?;
         let uid = parse_node_uid(&meta.uid).ok_or("staged write has an unparseable uid")?;
 
         if let Some(reason) = self.revision_conflict(&uid, &meta, &blob)? {
@@ -2283,6 +2294,22 @@ impl Core {
                 &written,
             )
             .map_err(|e| self.errno_error(e, "gap-fill from base failed"))?;
+            // The blob is whole now. Recorded, so that a retry after a lost
+            // answer can match these bytes against the server's revision
+            // (`revision_conflict`) instead of forking a conflict copy of the
+            // user's own write.
+            meta.complete = true;
+            match serde_json::to_string(&meta) {
+                Ok(json) => {
+                    let path = op.blob_path.as_deref().unwrap_or_default();
+                    if let Err(e) = self.db.update_op_meta_for_blob(op.id, path, &json) {
+                        warn!(%uid, error = %e,
+                              "recording a gap-filled blob as whole failed; \
+                               a lost answer may land it as a conflict copy");
+                    }
+                }
+                Err(e) => warn!(%uid, error = %e, "serializing a gap-filled sidecar failed"),
+            }
         }
 
         let name = self.node_name(&uid);
@@ -2303,7 +2330,7 @@ impl Core {
         let reader = CountingReader::new(File::open(&blob)?, &guard).with_cancel(cancel.flag());
         let started = Instant::now();
         let sent = self.block_on_within(
-            link::upload_deadline(meta.len),
+            link::upload_deadline(meta.len, self.transfers.upload_cap()),
             self.drive
                 .upload_new_revision_from(&uid, reader, meta.len as i64, thumbnails, None),
         );
@@ -2678,7 +2705,9 @@ fn proton_error<'e>(e: &'e (dyn std::error::Error + 'static)) -> Option<&'e Prot
 /// is, or `Some(None)` for a failure that is not a refusal.
 fn refusal(e: &(dyn std::error::Error + 'static)) -> Option<Option<SyncIssue>> {
     let proton = proton_error(e)?;
-    if is_network_error(proton) {
+    // A refused session refuses everything, so it says nothing about this
+    // op either; the mount is offline for it (`Core::lost_link`).
+    if is_network_error(proton) || pdfs_core::error::session_revoked(proton) {
         return None;
     }
     let ProtonError::Api(api) = proton else {
@@ -2759,24 +2788,43 @@ fn waits_for_name(e: &(dyn std::error::Error + 'static)) -> bool {
     std::iter::successors(Some(e), |e| e.source()).any(|e| e.is::<NameHeld>())
 }
 
+/// How long an op waits after its `attempts`-th failure: doubling from
+/// [`DRAIN_BACKOFF_MIN`] up to [`DRAIN_BACKOFF_MAX`], plus up to a fifth more,
+/// different for each op (`seed`), so that ops that failed together are not
+/// all retried in the same second. One that waits for a name (`held`) waits
+/// the minimum.
+///
+/// The doubling stopped at 2^6, 128 s, so the maximum was never reached.
+fn drain_backoff(attempts: i64, held: bool, seed: i64) -> Duration {
+    if held {
+        return DRAIN_BACKOFF_MIN;
+    }
+    let base = DRAIN_BACKOFF_MIN
+        .saturating_mul(1u32 << attempts.clamp(0, 8))
+        .min(DRAIN_BACKOFF_MAX);
+    // A cheap, stable spread: the same op and attempt always wait the same.
+    let spread = (seed.wrapping_mul(0x9E37_79B9).wrapping_add(attempts) as u64 % 21) as u32;
+    base + base * spread / 100
+}
+
 /// How many attempts an op waits for a rename or a create on the wire to free
 /// the name it wants. Two files swapping names each wait for the other, so the
 /// wait has to end; a conflict name ends it.
 const NAME_HOLD_ATTEMPTS: i64 = 4;
 
-/// How much older than its op a remote node may be and still be the one an
-/// unanswered call made. The op is queued the moment the call gives up, so the
-/// node is at most one call's deadline older; the rest is clock skew between
-/// this machine and Proton.
+/// How much older than its op's first send a remote node may be and still be
+/// the one an unanswered call made. The node is made during that call, so it
+/// is at most one call's deadline older; the rest is clock skew between this
+/// machine and Proton.
 const ADOPT_WINDOW_MS: i64 = 2 * 60 * 1000;
 
 /// Whether `twin`, found holding the name a queued create wants, is the node an
-/// earlier, unanswered attempt at that create made: the same kind, created
-/// around when the op was queued, and for a file still empty, as the mount's
+/// earlier, unanswered attempt at that create made: the same kind, created no
+/// earlier than around when the op was first sent (`first_sent_ms`), and for a file still empty, as the mount's
 /// create leaves it, or holding exactly bytes the op uploaded, whose SHA-1 is
 /// one of `sent`.
-fn adoptable(is_dir: bool, twin: &Node, op_created_ms: i64, sent: &[String]) -> bool {
-    if twin.creation_time.saturating_mul(1000) < op_created_ms - ADOPT_WINDOW_MS {
+fn adoptable(is_dir: bool, twin: &Node, first_sent_ms: i64, sent: &[String]) -> bool {
+    if twin.creation_time.saturating_mul(1000) < first_sent_ms - ADOPT_WINDOW_MS {
         return false;
     }
     match &twin.kind {
@@ -2833,6 +2881,23 @@ fn sleep_for_drain_work(
     *woken = false;
 }
 
+/// How long an idle drain worker sleeps: until the earliest queued op falls
+/// due, at most the idle poll.
+///
+/// A worker that claims nothing — offline or paused — sleeps the full idle
+/// poll whatever is due. Every op already queued is due "now" for it, so
+/// sleeping until then was a zero wait, and all the workers spun on the queue
+/// for as long as the outage lasted (`docs/BUGS.md` B200). A reconnect or a
+/// resume wakes the drain, so nothing waits the full poll for it.
+fn idle_wait(claiming: bool, earliest_due: Option<i64>, now: i64) -> Duration {
+    match earliest_due {
+        Some(ts) if claiming => {
+            Duration::from_millis((ts - now).max(0) as u64).min(DRAIN_IDLE_POLL)
+        }
+        _ => DRAIN_IDLE_POLL,
+    }
+}
+
 fn placed_in(st: &crate::state::State, uid: &NodeUid) -> Option<(String, Option<NodeUid>)> {
     let entry = st.by_uid.get(uid).and_then(|ino| st.entries.get(ino))?;
     Some((entry.node.name.clone(), entry.node.parent_uid.clone()))
@@ -2858,6 +2923,23 @@ mod tests {
         assert!(started.elapsed() < Duration::from_secs(1));
     }
 
+    #[test]
+    fn an_offline_worker_waits_the_idle_poll_for_a_past_due_op() {
+        // The op fell due long ago, and offline nobody attempts it, so it
+        // stays due: waiting for it was a zero wait, forever (B200).
+        assert_eq!(idle_wait(false, Some(0), 10_000), DRAIN_IDLE_POLL);
+    }
+
+    #[test]
+    fn a_claiming_worker_waits_only_until_the_next_op_falls_due() {
+        assert_eq!(
+            idle_wait(true, Some(12_000), 10_000),
+            Duration::from_secs(2)
+        );
+        assert_eq!(idle_wait(true, Some(0), 10_000), Duration::ZERO);
+        assert_eq!(idle_wait(true, None, 10_000), DRAIN_IDLE_POLL);
+    }
+
     fn pending(kind: &str) -> PendingOp {
         PendingOp {
             id: 0,
@@ -3324,6 +3406,22 @@ mod tests {
         }
     }
 
+    #[test]
+    fn a_failing_op_backs_off_to_the_maximum_with_a_spread() {
+        let at = |attempts| drain_backoff(attempts, false, 7);
+        assert!(at(1) >= DRAIN_BACKOFF_MIN * 2);
+        assert!(at(2) > at(1));
+        // Reached, which the doubling capped at 2^6 never did.
+        assert!(at(8) >= DRAIN_BACKOFF_MAX);
+        assert!(at(30) <= DRAIN_BACKOFF_MAX + DRAIN_BACKOFF_MAX / 5);
+        // Ops that failed together do not all come back together.
+        let waits: std::collections::HashSet<_> =
+            (1..=20).map(|id| drain_backoff(8, false, id)).collect();
+        assert!(waits.len() > 5, "{waits:?}");
+        // A wait for a name stays short however often it repeats.
+        assert_eq!(drain_backoff(30, true, 7), DRAIN_BACKOFF_MIN);
+    }
+
     #[test]
     fn only_a_fresh_empty_twin_of_the_same_kind_is_adopted() {
         // The op was queued at t=1000 s, after a create that got no answer.

crates/pdfs-fuse/src/drive.rs

@@ -8,8 +8,10 @@
 //! real client implements it by forwarding, and the simulation tests implement
 //! it with an in-memory Drive that injects Drive's known faults.
 //!
-//! Sharing, Photos, devices, invitations and public links stay on the concrete
-//! client (`Core::client`) until a test needs them faked.
+//! Sharing, Photos, invitations, public links and the rest of the device calls
+//! stay on the concrete client (`Core::client`) until a test needs them faked.
+//! Listing and registering devices are here, so a simulated daemon can sync a
+//! local folder.
 //!
 //! The method names match the client's own, so a call site reads the same
 //! whichever it goes through. The client's generic methods (a reader or writer
@@ -26,7 +28,8 @@ use proton_drive_rs::proton_sdk::account::Quota;
 use proton_drive_rs::proton_sdk::error::Result;
 use proton_drive_rs::proton_sdk::ids::{DriveEventId, NodeUid};
 use proton_drive_rs::{
-    DriveEvent, DriveEventScopeId, Node, NodeMoveItem, ProtonDriveClient, RevisionReader, Thumbnail,
+    AvailableNameTarget, Device, DeviceType, DriveEvent, DriveEventScopeId, Node, NodeMoveItem,
+    ProtonDriveClient, RevisionReader, Thumbnail,
 };
 
 /// One outcome per node of a batch request; see [`ProtonDriveClient::trash_nodes`].
@@ -135,6 +138,22 @@ pub(crate) trait DriveApi: Send + Sync {
 
     async fn move_node(&self, uid: &NodeUid, new_parent: &NodeUid) -> Result<()>;
 
+    /// See [`ProtonDriveClient::copy_node`].
+    async fn copy_node(
+        &self,
+        uid: &NodeUid,
+        new_parent: &NodeUid,
+        name: Option<&str>,
+    ) -> Result<NodeUid>;
+
+    /// See [`ProtonDriveClient::get_available_name`].
+    async fn get_available_name(
+        &self,
+        parent_uid: &NodeUid,
+        name: &str,
+        target: AvailableNameTarget,
+    ) -> Result<String>;
+
     fn move_nodes_streaming<'a>(
         &'a self,
         items: Vec<NodeMoveItem>,
@@ -154,6 +173,12 @@ pub(crate) trait DriveApi: Send + Sync {
     /// The account's storage, across every Proton product.
     async fn quota(&self) -> Result<Quota>;
 
+    /// Every computer that backs up to the account.
+    async fn enumerate_devices(&self) -> Result<Vec<Device>>;
+
+    /// Register a computer, with a root folder of its own named `name`.
+    async fn create_device(&self, name: &str, device_type: DeviceType) -> Result<Device>;
+
     /// Called by the drain once it has let go of the blob of an upload to
     /// `uid` that landed, or retired the create that made `uid`, before the
     /// tree has the node, so a simulation can hold it there. Blocks the drain
@@ -439,6 +464,24 @@ impl DriveApi for ProtonDriveClient {
         ProtonDriveClient::move_node(self, uid, new_parent).await
     }
 
+    async fn copy_node(
+        &self,
+        uid: &NodeUid,
+        new_parent: &NodeUid,
+        name: Option<&str>,
+    ) -> Result<NodeUid> {
+        ProtonDriveClient::copy_node(self, uid, new_parent, name).await
+    }
+
+    async fn get_available_name(
+        &self,
+        parent_uid: &NodeUid,
+        name: &str,
+        target: AvailableNameTarget,
+    ) -> Result<String> {
+        ProtonDriveClient::get_available_name(self, parent_uid, name, target).await
+    }
+
     fn move_nodes_streaming<'a>(
         &'a self,
         items: Vec<NodeMoveItem>,
@@ -470,4 +513,12 @@ impl DriveApi for ProtonDriveClient {
     async fn quota(&self) -> Result<Quota> {
         ProtonDriveClient::quota(self).await
     }
+
+    async fn enumerate_devices(&self) -> Result<Vec<Device>> {
+        ProtonDriveClient::enumerate_devices(self).await
+    }
+
+    async fn create_device(&self, name: &str, device_type: DeviceType) -> Result<Device> {
+        ProtonDriveClient::create_device(self, name, device_type).await
+    }
 }

crates/pdfs-fuse/src/events.rs

@@ -235,6 +235,8 @@ fn status_keys(status: &CtlResponse) -> (String, String) {
         used,
         budget,
         online,
+        session_expired,
+        tokens_unsaved,
         pending_uploads,
         pending_changes,
         ..
@@ -247,7 +249,7 @@ fn status_keys(status: &CtlResponse) -> (String, String) {
     );
     let key = format!(
         "{queue}/{staged_bytes}/{paused}/{paused_until:?}/{username}/{mountpoint}/{pinned}/\
-         {used}/{budget}/{online}"
+         {used}/{budget}/{online}/{session_expired}/{tokens_unsaved}"
     );
     (key, queue)
 }
@@ -325,6 +327,9 @@ mod tests {
             budget: 0,
             pins: Vec::new(),
             online: true,
+            session_expired: false,
+            tokens_unsaved: false,
+            version: "3.3.0".into(),
             pending_uploads: 1,
             pending_changes: 0,
         };

crates/pdfs-fuse/src/filesystem.rs

@@ -261,10 +261,13 @@ impl Filesystem for ProtonFs {
         // in-flight (possibly unsaved) content: authored bytes come from the
         // scratch file, untouched bytes from the base.
         //
-        // This path stays on the dispatch loop. `write` runs there too, so
-        // keeping its reads there as well preserves the ordering the write path
-        // has always had between a write and a read of the same handle; a mostly
-        // local read is not worth reasoning about that for.
+        // Answered on the dispatch loop when everything it needs is on this
+        // machine, which keeps the order `write` has with reads of the same
+        // handle. A base range that has to be downloaded goes to a worker
+        // instead, with the handle as it was when the read came in: the kernel
+        // issued the read before any write that comes after it, so that is
+        // the content it asked for. On the loop, the download held every
+        // request of the mount (`docs/BUGS.md` B227).
         let handle = {
             let st = self.core.state();
             st.active_writes.get(&ino.0).map(|h| {
@@ -279,7 +282,7 @@ impl Filesystem for ProtonFs {
             })
         };
         if let Some((file, len, uid, base_mtime, base_size, written)) = handle {
-            match self.core.serve_open_read(
+            match self.core.serve_open_read_local(
                 &file,
                 len,
                 &uid,
@@ -289,7 +292,25 @@ impl Filesystem for ProtonFs {
                 offset,
                 size as u64,
             ) {
-                Ok(bytes) => reply.data(&bytes),
+                Ok(Some(bytes)) => reply.data(&bytes),
+                Ok(None) => {
+                    let fs = self.clone();
+                    self.core.workers.run(Lane::Transfer, "read", move || {
+                        match fs.core.serve_open_read(
+                            &file,
+                            len,
+                            &uid,
+                            base_mtime,
+                            base_size,
+                            &written,
+                            offset,
+                            size as u64,
+                        ) {
+                            Ok(bytes) => reply.data(&bytes),
+                            Err(e) => reply.error(e),
+                        }
+                    });
+                }
                 Err(e) => reply.error(e),
             }
             return;
@@ -409,58 +430,10 @@ impl Filesystem for ProtonFs {
             reply.error(error);
             return;
         }
-        let fh = fh.0;
-        // Stage the bytes straight into the scratch file (no base download): only
-        // the untouched remainder is pulled from the remote, and only at commit.
-        let file = {
-            let st = self.core.state();
-            match st.handles.get(&fh).and_then(|&i| st.active_writes.get(&i)) {
-                Some(aw) => aw.file.clone(),
-                None => {
-                    reply.error(Errno::EBADF);
-                    return;
-                }
-            }
-        };
-        if let Err(e) = file.write_all_at(data, offset) {
-            error!(ino = ino.0, fh, error = %e, "scratch write failed");
-            // A full local disk is not a broken file: answer `ENOSPC` so the
-            // application can say so (and so `cp`/editors take their own
-            // out-of-space path), and free what the cache is holding — the
-            // scratch file the next write goes to shares that filesystem.
-            if e.raw_os_error() == Some(libc::ENOSPC) {
-                self.core.cache.emergency_evict();
-                reply.error(Errno::ENOSPC);
-            } else {
-                reply.error(Errno::EIO);
-            }
-            return;
+        match self.stage_write(ino.0, fh.0, offset, data) {
+            Ok(()) => reply.written(data.len() as u32),
+            Err(error) => reply.error(error),
         }
-        let new_len = {
-            let mut st = self.core.state();
-            let Some(aw) = st
-                .handles
-                .get(&fh)
-                .copied()
-                .and_then(|i| st.active_writes.get_mut(&i))
-            else {
-                reply.error(Errno::EBADF);
-                return;
-            };
-            aw.record_write(offset, offset + data.len() as u64);
-            let len = aw.len;
-            st.set_size(ino.0, len);
-            len
-        };
-        debug!(
-            ino = ino.0,
-            fh,
-            offset,
-            len = data.len(),
-            new_len,
-            "staged write"
-        );
-        reply.written(data.len() as u32);
     }
 
     #[allow(clippy::too_many_arguments)]
@@ -556,48 +529,62 @@ impl Filesystem for ProtonFs {
             return;
         }
         let new_end = offset.saturating_add(length);
-        let keep_size = (mode & 1) != 0; // FALLOC_FL_KEEP_SIZE
-
-        let is_punch_hole = (mode & 0x02) != 0; // FALLOC_FL_PUNCH_HOLE
-
-        let res = {
+        // Only the modes whose effect on the scratch file this handle can
+        // record. Anything else went through to the scratch file untracked:
+        // a zeroed range was refilled from the base at commit, and a collapse
+        // or insert shifted bytes that `len` and `written` did not follow
+        // (`docs/BUGS.md` B224). `EOPNOTSUPP` is also what makes glibc's
+        // `posix_fallocate` fall back to writing zeros.
+        let Some(kind) = falloc_kind(mode) else {
+            reply.error(Errno::EOPNOTSUPP);
+            return;
+        };
+        let file = {
+            let st = self.core.state();
+            match st.handles.get(&_fh.0).and_then(|i| st.active_writes.get(i)) {
+                Some(aw) => aw.file.clone(),
+                None => {
+                    reply.error(if st.entries.contains_key(&ino.0) {
+                        Errno::EBADF
+                    } else {
+                        Errno::ENOENT
+                    });
+                    return;
+                }
+            }
+        };
+        // The syscall can take a while on a large range; the state lock is
+        // not held across it, as `write` does not hold it across its I/O.
+        let ret = {
+            use std::os::unix::io::AsRawFd;
+            unsafe { libc::fallocate(file.as_raw_fd(), mode, offset as i64, length as i64) }
+        };
+        let res = if ret != 0 {
+            Err(Errno::from(std::io::Error::last_os_error()))
+        } else {
             let mut st = self.core.state();
-            match st
+            if let Some(aw) = st
                 .handles
                 .get(&_fh.0)
                 .copied()
                 .and_then(|i| st.active_writes.get_mut(&i))
             {
-                Some(aw) => {
-                    use std::os::unix::io::AsRawFd;
-                    let fd = aw.file.as_raw_fd();
-                    let ret = unsafe { libc::fallocate(fd, mode, offset as i64, length as i64) };
-                    if ret == 0 {
-                        if is_punch_hole {
-                            // A punched range reads as zero. Mark it authored so
-                            // queue_revision does not refill it from the remote
-                            // baseline and silently undo the hole at commit.
-                            aw.written.add(offset, new_end.min(aw.len));
-                            aw.dirty = true;
-                        } else if !keep_size && new_end > aw.len {
-                            aw.written.add(aw.len, new_end);
-                            aw.len = new_end;
-                            aw.dirty = true;
-                            st.set_size(ino.0, new_end);
-                        }
-                        Ok(())
-                    } else {
-                        Err(Errno::EIO)
-                    }
+                let len = aw.len;
+                let (authored, grown) = kind.effect(offset, new_end, len);
+                if let Some((from, to)) = authored {
+                    // Zeroed or punched bytes read as zero. Marked authored so
+                    // queue_revision does not refill them from the remote
+                    // baseline and silently undo them at commit.
+                    aw.written.add(from, to);
+                    aw.dirty = true;
                 }
-                None => {
-                    if st.entries.contains_key(&ino.0) {
-                        Err(Errno::EBADF)
-                    } else {
-                        Err(Errno::ENOENT)
-                    }
+                if let Some(end) = grown {
+                    aw.len = end;
+                    aw.dirty = true;
+                    st.set_size(ino.0, end);
                 }
             }
+            Ok(())
         };
 
         match res {
@@ -606,18 +593,47 @@ impl Filesystem for ProtonFs {
         }
     }
 
-    /// `close(2)` calls flush before release. The upload is queued in `release`
-    /// and performed in the background, so there is nothing
-    /// to push here — the written bytes are already in the scratch file.
+    /// `close(2)` calls flush before release, and flush is the only one of the
+    /// two whose answer reaches the program: the kernel drops `release`'s. So
+    /// the scratch file of a handle with writes on it is synced here, on a
+    /// worker, and a full disk or a failing one is what `close` returns.
+    ///
+    /// Before, flush answered `ok` at once and `release` synced the file, so an
+    /// `ENOSPC` that delayed allocation held back until then was reported to
+    /// nobody, and the program took the save as done (`docs/BUGS.md` B222).
+    /// It also means `release`, which stays on the dispatch loop for ordering,
+    /// finds the pages already on disk instead of writing back a whole file
+    /// while every other request on the mount waits.
     fn flush(
         &self,
         _req: &Request,
         _ino: INodeNo,
-        _fh: FileHandle,
+        fh: FileHandle,
         _lock_owner: LockOwner,
         reply: ReplyEmpty,
     ) {
-        reply.ok();
+        let file = {
+            let st = self.core.state();
+            st.handles
+                .get(&fh.0)
+                .and_then(|ino| st.active_writes.get(ino))
+                .filter(|aw| aw.dirty)
+                .map(|aw| aw.file.clone())
+        };
+        let Some(file) = file else {
+            reply.ok();
+            return;
+        };
+        let fs = self.clone();
+        self.core
+            .workers
+            .run(Lane::Transfer, "flush", move || match file.sync_data() {
+                Ok(()) => reply.ok(),
+                Err(e) => {
+                    error!(fh = fh.0, error = %e, "flush of scratch file failed");
+                    reply.error(fs.scratch_sync_errno(&e));
+                }
+            });
     }
 
     /// Durability here means the scratch file, not the remote: a caller asking
@@ -655,7 +671,7 @@ impl Filesystem for ProtonFs {
         reply: ReplyEmpty,
     ) {
         let ino = self.tree(ino);
-        let (handle, unlinked_uid) = {
+        let (handle, unlinked_uid, releasing) = {
             let mut st = self.core.state();
             let unlinked_uid = release_unlinked_entry(&mut st, ino.0);
             let ino = st.handles.remove(&fh.0);
@@ -668,7 +684,11 @@ impl Filesystem for ProtonFs {
                     None
                 }
             });
-            (h, unlinked_uid)
+            let releasing = ino.filter(|_| h.is_some());
+            if let Some(ino) = releasing {
+                st.releasing.insert(ino);
+            }
+            (h, unlinked_uid, releasing)
         };
         // Deliberately **not** handed to a worker, unlike the other slow
         // handlers here. The kernel does not wait for a `release` reply before
@@ -685,6 +705,9 @@ impl Filesystem for ProtonFs {
         // finish it (audit F1). What is left is a rename, two fsyncs, a database
         // insert, and at most a bounded copy out of the local cache.
         self.finish_release(handle, unlinked_uid, reply);
+        if let Some(ino) = releasing {
+            self.core.state().releasing.remove(&ino);
+        }
     }
 
     fn unlink(&self, _req: &Request, parent: INodeNo, name: &OsStr, reply: ReplyEmpty) {
@@ -952,20 +975,59 @@ impl Filesystem for ProtonFs {
     fn copy_file_range(
         &self,
         _req: &Request,
-        _ino_in: INodeNo,
+        ino_in: INodeNo,
         _fh_in: FileHandle,
-        _offset_in: u64,
-        _ino_out: INodeNo,
-        _fh_out: FileHandle,
-        _offset_out: u64,
-        _len: u64,
-        _flags: CopyFileRangeFlags,
+        offset_in: u64,
+        ino_out: INodeNo,
+        fh_out: FileHandle,
+        offset_out: u64,
+        len: u64,
+        flags: CopyFileRangeFlags,
         reply: ReplyWrite,
     ) {
-        // Also must stay ENOSYS: there is no server-side copy, and this is the
-        // errno that sends coreutils (and the kernel) down the read/write path
-        // instead of failing the copy outright.
-        reply.error(Errno::ENOSYS);
+        // Copied here when the source bytes are on this machine, as `write`
+        // would stage them, minus a FUSE round trip per page: `cp` of a cached
+        // 256 MiB file ran at about 100 MiB/s through read and write. Anything
+        // that would have to be downloaded gets `EOPNOTSUPP`, which makes the
+        // kernel copy that one call through read and write itself; `ENOSYS`
+        // would turn the op off for the whole mount. There is no server-side
+        // copy into a file `cp` has already created, so the copy still uploads.
+        //
+        // On the dispatch loop, like `write`, so it keeps its order with the
+        // reads and writes of the same handle. [`COPY_RANGE_MAX`] bounds how
+        // long one call holds the loop.
+        let (ino_in, ino_out) = (self.tree(ino_in), self.tree(ino_out));
+        if !flags.is_empty() || ino_in == ino_out {
+            reply.error(Errno::EOPNOTSUPP);
+            return;
+        }
+        if let Err(error) = self.core.require_writable(ino_out.0) {
+            reply.error(error);
+            return;
+        }
+        let bytes = match self
+            .core
+            .read_local(ino_in.0, offset_in, len.min(COPY_RANGE_MAX))
+        {
+            Ok(Some(bytes)) => bytes,
+            Ok(None) => {
+                debug!(ino_in = ino_in.0, offset_in, "copy range not local");
+                reply.error(Errno::EOPNOTSUPP);
+                return;
+            }
+            Err(error) => {
+                reply.error(error);
+                return;
+            }
+        };
+        if bytes.is_empty() {
+            reply.written(0);
+            return;
+        }
+        match self.stage_write(ino_out.0, fh_out.0, offset_out, &bytes) {
+            Ok(()) => reply.written(bytes.len() as u32),
+            Err(error) => reply.error(error),
+        }
     }
 }
 
@@ -993,6 +1055,11 @@ pub struct ProtonFs {
 /// worker busy indefinitely.
 const OPEN_BASE_ATTEMPTS: u32 = 3;
 
+/// The most one `copy_file_range` call copies; the caller loops for the rest.
+/// A local copy of this much takes milliseconds, which is how long it holds
+/// the dispatch loop.
+const COPY_RANGE_MAX: u64 = 16 * 1024 * 1024;
+
 /// One directory's entries as `readdir` reports them: `.` and `..` first, then
 /// the interned children in `children` order.
 ///
@@ -1022,6 +1089,52 @@ fn build_listing(st: &State, ino: u64) -> DirListing {
 /// The cookie handed back is the index of the *next* entry, so a resumed call
 /// continues exactly where the last one stopped — which is only true because
 /// the listing behind those indexes is a snapshot (`docs/BUGS.md` B43).
+/// What an `fallocate` mode does to a write handle, for the modes it can
+/// record (`docs/BUGS.md` B224).
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+enum FallocKind {
+    /// Reserve space; past the end it grows the file unless `keep_size`.
+    Allocate { keep_size: bool },
+    /// Deallocate a range inside the file, which then reads as zero.
+    Punch,
+    /// Zero a range; past the end it grows the file unless `keep_size`.
+    Zero { keep_size: bool },
+}
+
+fn falloc_kind(mode: i32) -> Option<FallocKind> {
+    const KEEP: i32 = libc::FALLOC_FL_KEEP_SIZE;
+    const PUNCH: i32 = libc::FALLOC_FL_PUNCH_HOLE;
+    const ZERO: i32 = libc::FALLOC_FL_ZERO_RANGE;
+    match mode {
+        0 => Some(FallocKind::Allocate { keep_size: false }),
+        KEEP => Some(FallocKind::Allocate { keep_size: true }),
+        m if m == PUNCH | KEEP => Some(FallocKind::Punch),
+        ZERO => Some(FallocKind::Zero { keep_size: false }),
+        m if m == ZERO | KEEP => Some(FallocKind::Zero { keep_size: true }),
+        _ => None,
+    }
+}
+
+impl FallocKind {
+    /// For `[offset, end)` on a file `len` bytes long: the range that now
+    /// reads as zero and must count as written, and the new length if it grew.
+    fn effect(self, offset: u64, end: u64, len: u64) -> (Option<(u64, u64)>, Option<u64>) {
+        let grow = |keep_size: bool| (!keep_size && end > len).then_some(end);
+        let zeroed = |to: u64| (offset < to).then_some((offset, to));
+        match self {
+            // Space past the old end reads as zero, and nothing before it moved.
+            Self::Allocate { keep_size } => {
+                (grow(keep_size).map(|end| (len, end)), grow(keep_size))
+            }
+            Self::Punch => (zeroed(end.min(len)), None),
+            Self::Zero { keep_size } => {
+                let to = if keep_size { end.min(len) } else { end };
+                (zeroed(to), grow(keep_size))
+            }
+        }
+    }
+}
+
 fn reply_listing(listing: &DirListing, offset: u64, root: u64, mut reply: ReplyDirectory) {
     for (i, (ino, is_dir, name)) in listing.iter().enumerate().skip(offset as usize) {
         let ft = if *is_dir {
@@ -1267,8 +1380,12 @@ impl ProtonFs {
         //
         // Complete pending blobs are the common case and can be copied without
         // any network access. An incomplete blob still has gaps referring to
-        // the remote base; stacking another write on it cannot be represented
-        // safely by WriteHandle, so fail the open rather than risk corruption.
+        // the remote base, and stacking another write on it cannot be
+        // represented by WriteHandle, so the copy's gaps are filled from that
+        // base first, as the drain fills them before an upload. Only when that
+        // fails (offline, or the base is gone) does the open fail: refusing
+        // every such open failed a create over a file whose partial edit had
+        // not drained yet (`docs/BUGS.md` B204).
         //
         // Reading that blob and installing the handle cannot be done under one
         // lock — the copy is the size of the file — so the base is re-checked at
@@ -1302,10 +1419,6 @@ impl ProtonFs {
                     }
                 }
                 let pending_base = self.core.pending.lock().get(&uid).cloned();
-                if pending_base.as_ref().is_some_and(|p| !p.meta.complete) {
-                    error!(%uid, "refusing write over incomplete queued revision");
-                    break 'install Err(Errno::EIO);
-                }
                 let (file, path) = match self.core.cache.create_scratch() {
                     Ok(x) => x,
                     Err(e) => {
@@ -1321,10 +1434,37 @@ impl ProtonFs {
                     // (`ContentCache::clone_or_copy`).
                     if let Err(e) = ContentCache::clone_or_copy(&pending.path, &path) {
                         let _ = std::fs::remove_file(&path);
+                        // The drain lets go of the pending entry before it
+                        // discards the blob, so a blob that went away under the
+                        // copy is a revision that landed or was replaced: the
+                        // same race the re-check below catches, only earlier.
+                        if self.core.pending_blob(&uid).as_ref() != Some(&pending.path) {
+                            warn!(%uid, attempt, "queued revision went away while opening for write; retrying");
+                            continue;
+                        }
                         error!(%uid, source = %pending.path.display(), error = %e,
                             "copy queued revision into write scratch failed");
                         break 'install Err(Errno::EIO);
                     }
+                    if !pending.meta.complete {
+                        let mut authored = Intervals::default();
+                        for &(s, e) in &pending.meta.authored {
+                            authored.add(s, e);
+                        }
+                        if let Err(error) = self.core.fill_gaps(
+                            &uid,
+                            &file,
+                            pending.meta.len,
+                            pending.meta.base_mtime,
+                            pending.meta.base_size,
+                            &authored,
+                        ) {
+                            let _ = std::fs::remove_file(&path);
+                            error!(%uid, ?error, "cannot complete the queued revision a write open is based on");
+                            break 'install Err(error);
+                        }
+                        debug!(%uid, "write open completed an incomplete queued revision");
+                    }
                     initial_written.add(0, pending.meta.len);
                 }
                 // Sampled *before* the state lock, never under it: no site in
@@ -1416,6 +1556,20 @@ impl ProtonFs {
     }
 
     /// The body of [`Filesystem::fsync`], run off the dispatch loop.
+    /// The errno to give a program for a failed sync of a scratch file.
+    /// Delayed allocation means a full disk usually surfaces at the sync
+    /// rather than at `write(2)`, and `ENOSPC` is what a program checks for.
+    fn scratch_sync_errno(&self, e: &std::io::Error) -> Errno {
+        match e.raw_os_error() {
+            Some(libc::ENOSPC) => {
+                self.core.cache.emergency_evict();
+                Errno::ENOSPC
+            }
+            Some(libc::EDQUOT) => Errno::EDQUOT,
+            _ => Errno::EIO,
+        }
+    }
+
     fn serve_fsync(&self, fh: FileHandle, reply: ReplyEmpty) {
         // Everything the durability sidecar needs, copied out so no lock is held
         // across the sync.
@@ -1436,22 +1590,18 @@ impl ProtonFs {
                 )
             })
         };
+        // A handle opened for reading has nothing of its own to make durable,
+        // and POSIX allows `fsync` on it; `EBADF` failed `sync FILE` and
+        // backup tools that sync what they read (`docs/BUGS.md` B222).
         let Some((f, path, uid, dirty, written, len, base_size, base_mtime, base_revision_id)) =
             handle
         else {
-            reply.error(Errno::EBADF);
+            reply.ok();
             return;
         };
         if let Err(e) = f.sync_all() {
             error!(fh = fh.0, error = %e, "fsync of scratch file failed");
-            // Delayed allocation means a full disk usually surfaces here rather
-            // than at `write(2)`; `ENOSPC` is what an application checks for.
-            if e.raw_os_error() == Some(libc::ENOSPC) {
-                self.core.cache.emergency_evict();
-                reply.error(Errno::ENOSPC);
-            } else {
-                reply.error(Errno::EIO);
-            }
+            reply.error(self.scratch_sync_errno(&e));
             return;
         }
         // A clean handle has nothing on it that the remote does not already
@@ -1502,6 +1652,48 @@ impl ProtonFs {
     }
 
     /// The body of [`Filesystem::create`], run off the dispatch loop.
+    /// Stage `data` at `offset` of the write handle `fh` on `ino`, straight into
+    /// its scratch file (no base download): only the untouched remainder is
+    /// pulled from the remote, and only at commit.
+    fn stage_write(&self, ino: u64, fh: u64, offset: u64, data: &[u8]) -> Result<(), Errno> {
+        let file = {
+            let st = self.core.state();
+            match st.handles.get(&fh).and_then(|&i| st.active_writes.get(&i)) {
+                Some(aw) => aw.file.clone(),
+                None => return Err(Errno::EBADF),
+            }
+        };
+        if let Err(e) = file.write_all_at(data, offset) {
+            error!(ino, fh, error = %e, "scratch write failed");
+            // A full local disk is not a broken file: answer `ENOSPC` so the
+            // application can say so (and so `cp`/editors take their own
+            // out-of-space path), and free what the cache is holding — the
+            // scratch file the next write goes to shares that filesystem.
+            if e.raw_os_error() == Some(libc::ENOSPC) {
+                self.core.cache.emergency_evict();
+                return Err(Errno::ENOSPC);
+            }
+            return Err(Errno::EIO);
+        }
+        let new_len = {
+            let mut st = self.core.state();
+            let Some(aw) = st
+                .handles
+                .get(&fh)
+                .copied()
+                .and_then(|i| st.active_writes.get_mut(&i))
+            else {
+                return Err(Errno::EBADF);
+            };
+            aw.record_write(offset, offset + data.len() as u64);
+            let len = aw.len;
+            st.set_size(ino, len);
+            len
+        };
+        debug!(ino, fh, offset, len = data.len(), new_len, "staged write");
+        Ok(())
+    }
+
     fn serve_create(&self, parent: u64, name: &str, reply: ReplyCreate) {
         if let Err(error) = self.core.require_writable(parent) {
             reply.error(error);
@@ -1698,9 +1890,7 @@ impl ProtonFs {
         // empty, which it is, so reads stay offline-clean across a restart too.
         if local {
             st.children.insert(ino, Vec::new());
-            if let Err(e) = self.core.db.set_listed(&uid, true) {
-                warn!(%uid, error = %e, "db set_listed(true) failed for local folder");
-            }
+            st.record_listed(uid);
         }
         let entry = st.entries.get(&ino).unwrap();
         let attr = self.attr(ino, &entry.node, entry.access);
@@ -2186,7 +2376,7 @@ impl ProtonFs {
         // regardless — the file is gone from their point of view the moment the
         // command returns. The same when the network goes
         // away under the remote call below.
-        let queue_it = |reply: ReplyEmpty| match self.core.queue_trash(&uid, name) {
+        let queue_it = |reply: ReplyEmpty| match self.core.queue_trash(&uid, name, open_now) {
             Ok(()) => reply.ok(),
             Err(e) => reply.error(e),
         };
@@ -2318,3 +2508,60 @@ impl ProtonFs {
         }
     }
 }
+
+#[cfg(test)]
+mod falloc_tests {
+    use super::*;
+
+    #[test]
+    fn only_the_modes_a_handle_can_record_are_accepted() {
+        let keep = libc::FALLOC_FL_KEEP_SIZE;
+        assert_eq!(
+            falloc_kind(0),
+            Some(FallocKind::Allocate { keep_size: false })
+        );
+        assert_eq!(
+            falloc_kind(keep),
+            Some(FallocKind::Allocate { keep_size: true })
+        );
+        assert_eq!(
+            falloc_kind(libc::FALLOC_FL_PUNCH_HOLE | keep),
+            Some(FallocKind::Punch)
+        );
+        assert_eq!(
+            falloc_kind(libc::FALLOC_FL_ZERO_RANGE),
+            Some(FallocKind::Zero { keep_size: false })
+        );
+        for mode in [
+            libc::FALLOC_FL_PUNCH_HOLE,
+            libc::FALLOC_FL_COLLAPSE_RANGE,
+            libc::FALLOC_FL_INSERT_RANGE,
+            libc::FALLOC_FL_UNSHARE_RANGE,
+        ] {
+            assert_eq!(falloc_kind(mode), None, "{mode:#x}");
+        }
+    }
+
+    /// A zeroed range was left unwritten, so the commit filled it back in
+    /// from the remote base (`docs/BUGS.md` B224).
+    #[test]
+    fn a_zeroed_or_punched_range_counts_as_written() {
+        let zero = FallocKind::Zero { keep_size: false };
+        assert_eq!(zero.effect(10, 20, 100), (Some((10, 20)), None));
+        assert_eq!(zero.effect(90, 120, 100), (Some((90, 120)), Some(120)));
+        let zero_keep = FallocKind::Zero { keep_size: true };
+        assert_eq!(zero_keep.effect(90, 120, 100), (Some((90, 100)), None));
+        assert_eq!(
+            FallocKind::Punch.effect(90, 120, 100),
+            (Some((90, 100)), None)
+        );
+        assert_eq!(FallocKind::Punch.effect(120, 130, 100), (None, None));
+        let alloc = FallocKind::Allocate { keep_size: false };
+        assert_eq!(alloc.effect(0, 50, 100), (None, None));
+        assert_eq!(alloc.effect(90, 120, 100), (Some((100, 120)), Some(120)));
+        assert_eq!(
+            FallocKind::Allocate { keep_size: true }.effect(90, 120, 100),
+            (None, None)
+        );
+    }
+}

crates/pdfs-fuse/src/lib.rs

@@ -74,8 +74,8 @@ use proton_drive_rs::proton_sdk::api::ResponseCode;
 use proton_drive_rs::proton_sdk::error::ProtonError;
 use proton_drive_rs::proton_sdk::ids::{DriveEventId, LinkId, NodeUid, ShareId, VolumeId};
 use proton_drive_rs::{
-    DriveEvent, DriveEventScopeId, MemberRole, Node, NodeKind, NodeMoveItem, ProtonDriveClient,
-    ProtonPhotosClient, SharedWithMeItem, ThumbnailType,
+    AvailableNameTarget, DriveEvent, DriveEventScopeId, MemberRole, Node, NodeKind, NodeMoveItem,
+    ProtonDriveClient, ProtonPhotosClient, SharedWithMeItem, ThumbnailType,
 };
 
 mod albums;
@@ -116,6 +116,7 @@ mod upload;
 mod r#virtual;
 mod workers;
 use background::{forget_and_notify, run_event_sync, run_local_index, run_photos_event_sync};
+use link::BATCH_CALL_TIMEOUT;
 pub(crate) use mount::is_stale_mount;
 pub use mount::{MountOptions, MountOutcome, mount};
 use mount::{
@@ -123,6 +124,7 @@ use mount::{
 };
 use reads::{BlockFlight, BlockRing, PREFETCH_BUDGET, Prefetch, ReaderSlot, STREAM_BYPASS_MIN};
 use state::{Entry, Intervals, PendingRevision, State, StateGuard, WriteHandle};
+pub use systemd::{idle_sleep, status as notify_status};
 use tracing::{debug, error, info, warn};
 use transfers::{CountingWriter, JobGuard, OwnedCountingReader, TransferRegistry};
 use r#virtual::{
@@ -726,6 +728,8 @@ struct Core {
     /// can say what a pass is doing rather than just "syncing". An entry exists
     /// only while that folder's reconcile pass is running.
     sync_progress: Arc<Mutex<HashMap<i64, SyncProgress>>>,
+    /// Whether the folder-sync engine is alive, and which pass it is on.
+    sync_engine: Arc<sync::EngineHealth>,
     /// Channel to the folder-sync engine: nudges it to
     /// reconcile a folder, reconcile everything, or re-scan its watch set.
     sync_tx: std::sync::mpsc::Sender<sync::SyncMsg>,
@@ -743,6 +747,9 @@ struct Core {
     /// uploading that same tree — the engine would upload files as they vanish
     /// and then walk the FUSE mount as if it were local.
     sync_locks: Arc<Mutex<HashMap<i64, Arc<Mutex<()>>>>>,
+    /// Per-sync-folder paths the last pass could not read, so the activity feed
+    /// says so when the set changes rather than on every poll (B196).
+    sync_unscanned: Arc<Mutex<HashMap<i64, Vec<String>>>>,
     /// Nodes this daemon changed on the remote itself, and how many echoes of
     /// those changes the event feed still owes us.
     ///
@@ -1030,7 +1037,9 @@ impl Core {
 
         let core = self.clone();
         std::thread::spawn(move || {
-            let job = core.transfers.begin_job("Checking the cache database");
+            let job = core
+                .transfers
+                .begin_background_job("Checking the cache database");
             job.detail("Verifying every page");
             let problems = match core.db.integrity_check() {
                 Ok(problems) => problems,
@@ -2114,12 +2123,39 @@ impl Core {
         }
     }
 
-    /// Whether `ino`'s listing is already in memory, i.e. whether
-    /// [`Core::ensure_children`] would return without touching the network.
-    /// Lets a handler decide between answering inline and handing off to a
-    /// worker, at the cost of one uncontended map lookup.
+    /// Whether [`Core::ensure_children`] would answer for `ino` without
+    /// touching the network. Lets a handler decide between answering inline
+    /// and handing off to a worker.
+    ///
+    /// A resident listing is not enough on its own. A shared folder's, or the
+    /// Shared with me root's, is fetched again once it is a minute old, and
+    /// that fetch ran on the dispatch loop, so every request on the mount
+    /// waited for Drive to answer (`docs/BUGS.md` B219).
     fn children_cached(&self, ino: u64) -> bool {
-        self.state().children.contains_key(&ino)
+        let (uid, resident) = {
+            let st = self.state();
+            match st.entries.get(&ino) {
+                Some(e) => (e.uid.clone(), st.children.contains_key(&ino)),
+                // `list_children` answers ENOENT without the network.
+                None => return true,
+            }
+        };
+        if !resident {
+            return false;
+        }
+        let freshness = if is_virtual_uid(&uid) {
+            Some(SHARED_WITH_ME_SYNCED_MS.to_string())
+        } else if !self.is_own_or_virtual(&uid) && !is_local_uid(&uid) {
+            Some(Self::shared_folder_freshness_key(&uid))
+        } else {
+            None
+        };
+        freshness.is_none_or(|key| {
+            !listing_needs_refresh(
+                self.online.load(Ordering::Relaxed),
+                self.shared_listing_stale(&key),
+            )
+        })
     }
 
     /// Re-apply the optimistic size of any queued write to `nodes`.
@@ -2287,8 +2323,7 @@ impl Core {
 
         let generation = self.shared_generation.load(Ordering::SeqCst);
         let accepted = accepted_share_provenance(
-            self.rt
-                .block_on(self.client.enumerate_shared_with_me())
+            self.block_on_within(BATCH_CALL_TIMEOUT, self.client.enumerate_shared_with_me())
                 .map_err(|error| {
                     error!(%error, "enumerating shared roots failed");
                     Errno::EIO
@@ -2297,12 +2332,14 @@ impl Core {
         let nodes = if accepted.uids.is_empty() {
             Vec::new()
         } else {
-            self.rt
-                .block_on(self.drive.enumerate_nodes_light(&accepted.uids))
-                .map_err(|error| {
-                    error!(%error, "materializing shared roots failed");
-                    Errno::EIO
-                })?
+            self.block_on_within(
+                BATCH_CALL_TIMEOUT,
+                self.drive.enumerate_nodes_light(&accepted.uids),
+            )
+            .map_err(|error| {
+                error!(%error, "materializing shared roots failed");
+                Errno::EIO
+            })?
         };
         let virtual_uid = shared_with_me_uid();
         let published = prepare_shared_roots(&accepted, nodes, &virtual_uid);
@@ -2681,6 +2718,7 @@ impl Core {
             return Ok(());
         }
 
+        let preassigned = state::inos_for(&self.db, &filtered_nodes);
         let mut st = self.state();
         // Lost the race? Another thread already populated it.
         if st.children.contains_key(&ino) {
@@ -2702,15 +2740,14 @@ impl Core {
             })
             .map(|n| n.uid.clone())
             .collect();
-        let inos = st.intern_batch(ino, filtered_nodes);
+        let inos = st.intern_batch_with_inos(ino, filtered_nodes, preassigned);
         child_inos.extend(inos);
         st.children.insert(ino, child_inos);
         let root_snapshot = primary_root.then(|| RootListingSnapshot::capture(&st, ino).unwrap());
         // Record the listing as complete so a later restart (or a trimmed hot
-        // cache) can rebuild it from the DB without the API.
-        if let Err(e) = self.db.set_listed(&folder_uid, true) {
-            warn!(%folder_uid, error = %e, "db set_listed(true) failed");
-        }
+        // cache) can rebuild it from the DB without the API. Written with the
+        // children's rows when the lock goes, not under it.
+        st.record_listed(folder_uid.clone());
         drop(st);
         self.flush_access_changes();
         if let Some(snapshot) = root_snapshot {
@@ -2873,7 +2910,8 @@ impl Core {
         let (mut key, mut uids, mut slot) = (key, uids, slot);
         loop {
             for chunk in uids.chunks(SIZE_UPGRADE_CHUNK) {
-                let result = self.rt.block_on(self.drive.enumerate_nodes(chunk));
+                let result =
+                    self.block_on_within(BATCH_CALL_TIMEOUT, self.drive.enumerate_nodes(chunk));
                 self.apply_size_upgrade(key, result);
                 slot.chunk_done();
             }
@@ -3961,7 +3999,12 @@ impl Core {
     /// the cached ones, as when the trash is sent at once: a partial write
     /// fills its gaps from them, offline too (`docs/BUGS.md` B186). The final
     /// close or the trash landing, whichever comes last, lets go of them.
-    fn queue_trash(&self, uid: &NodeUid, name: &str) -> Result<(), Errno> {
+    ///
+    /// `open` is whether the caller found the file open. A create that landed
+    /// under a delete is trashed by its real uid before the tree has it, so
+    /// asking the tree alone took an open file for closed (`docs/BUGS.md`
+    /// B257).
+    fn queue_trash(&self, uid: &NodeUid, name: &str, open: bool) -> Result<(), Errno> {
         self.require_uid_writable(uid)?;
         // The bytes below are about to be discarded, and a drain worker may be
         // reading them onto the wire right now. Stop it first: with several
@@ -3976,7 +4019,7 @@ impl Core {
                 error!(%uid, error = %e, "queueing trash failed");
                 Errno::EIO
             })?;
-        let open_now = self.is_open_anywhere(uid);
+        let open_now = open || self.is_open_anywhere(uid);
         if open_now {
             let read_from = self.pending_blob(uid);
             self.release_dropped_below(
@@ -4221,8 +4264,10 @@ impl Core {
     }
 
     /// Pin the node at mountpoint-relative `rel`. A file downloads its full
-    /// plaintext into the content cache; a folder records a recursive pin and
-    /// downloads every descendant file (selective sync). Returns a human message.
+    /// plaintext into the content cache before this returns. A folder records a
+    /// recursive pin and downloads every descendant file on a background thread,
+    /// reported as a job: a big folder far outlasts the socket read timeout.
+    /// Returns a human message.
     fn pin(&self, rel: &Path) -> CoreResult<String> {
         let (ino, uid) = self.resolve(rel)?;
         let (name, is_folder, mtime, size) = {
@@ -4239,34 +4284,93 @@ impl Core {
             )
         };
         if is_folder {
+            // Offline, every download would fail and the folder would only look
+            // kept. Refuse instead, as a file pin does.
+            if !self.is_online() {
+                return Err(CoreError::offline());
+            }
             // Record the recursive pin first so every descendant is eviction-
             // exempt before we start filling the cache with the subtree.
             self.cache
                 .add_pin(&uid, rel, true)
                 .map_err(|e| CoreError::from_api(&e, "pin"))?;
-            let n = self.pin_subtree(ino)?;
-            return Ok(format!("{name} ({n} files)"));
+            let core = self.clone();
+            let folder = name.clone();
+            std::thread::Builder::new()
+                .name("pin-folder".into())
+                .spawn(move || core.pin_subtree(ino, &uid, &folder))
+                .map_err(|e| CoreError::internal(format!("spawn pin: {e}")))?;
+            return Ok(format!("{name}: downloading its files in the background"));
         }
-        let bytes = self
-            .download_file_tracked(&uid, &name, size)
-            .map_err(|e| CoreError::from_api(&e, "download"))?;
-        self.cache
-            .store(&uid, mtime, size, &bytes)
-            .map_err(|e| CoreError::internal(format!("cache store: {e}")))?;
+        self.fetch_content(&uid, &name, mtime, size)?;
         self.cache
             .add_pin(&uid, rel, false)
             .map_err(|e| CoreError::from_api(&e, "pin"))?;
         Ok(name)
     }
 
-    /// Download and cache every file in the subtree rooted at folder `ino`,
-    /// returning the count cached (already-fresh blobs counted, not re-fetched).
-    /// Walks the tree depth-first, enumerating each folder so a cold subtree is
-    /// fully discovered; the lock is dropped before each network download.
-    fn pin_subtree(&self, ino: u64) -> CoreResult<usize> {
+    /// Download and cache every file in the subtree rooted at the pinned folder
+    /// `ino` (`folder`, named `name`), as a job the front ends show. Walks the
+    /// tree depth-first, enumerating each folder so a cold subtree is fully
+    /// discovered; the lock is dropped before each network download. Stops when
+    /// the folder is unpinned or the daemon stops.
+    fn pin_subtree(&self, ino: u64, folder: &NodeUid, name: &str) {
+        let job = self
+            .transfers
+            .begin_job(format!("Making {name} available offline"));
+        match self.pin_subtree_files(ino) {
+            Ok(files) => {
+                job.set_total(files.len() as u64);
+                let mut failed = 0usize;
+                for (uid, file, mtime, size) in files {
+                    if self.shutdown.is_stopping() || !self.cache.is_pinned(folder) {
+                        return;
+                    }
+                    job.detail(file.clone());
+                    if let Err(e) = self.fetch_pinned(&uid, &file, mtime, size) {
+                        warn!(%uid, error = %e, "pin folder: download failed");
+                        failed += 1;
+                    }
+                    job.step();
+                }
+                info!(folder = %name, failed, "pin folder: done");
+            }
+            Err(e) => warn!(folder = %name, error = %e, "pin folder: enumerate failed"),
+        }
+    }
+
+    /// Cache the file `uid` for a folder pin. Its `mtime` and `size` were read
+    /// before the download, and a create landing or a remote edit can change
+    /// them while it runs. The blob is then stored under the old ones and reads
+    /// as stale, so the file is listed as kept but not available offline. Fetch
+    /// it again under the new ones, a few times at most.
+    fn fetch_pinned(&self, uid: &NodeUid, name: &str, mtime: i64, size: u64) -> CoreResult<()> {
+        let mut fetched = (mtime, size);
+        for _ in 0..3 {
+            self.fetch_content(uid, name, fetched.0, fetched.1)?;
+            let current = {
+                let st = self.state();
+                st.by_uid
+                    .get(uid)
+                    .and_then(|ino| st.entries.get(ino))
+                    .map(|e| (e.node.modification_time, node_size(&e.node)))
+            };
+            match current {
+                Some(now) if now != fetched => fetched = now,
+                _ => break,
+            }
+        }
+        Ok(())
+    }
+
+    /// Every file in the subtree rooted at folder `ino`.
+    fn pin_subtree_files(&self, ino: u64) -> CoreResult<Vec<(NodeUid, String, i64, u64)>> {
         let mut files: Vec<(NodeUid, String, i64, u64)> = Vec::new();
         let mut stack = vec![ino];
         while let Some(dir) = stack.pop() {
+            if self.shutdown.is_stopping() {
+                break;
+            }
             self.ensure_children(dir)
                 .map_err(|e| self.errno_error(e, "enumerate"))?;
             let st = self.state();
@@ -4287,22 +4391,7 @@ impl Core {
                 }
             }
         }
-        let mut count = 0;
-        for (uid, name, mtime, size) in files {
-            if self.cache.is_cached(&uid, mtime, size) {
-                count += 1;
-                continue;
-            }
-            match self.download_file_tracked(&uid, &name, size) {
-                Ok(bytes) => {
-                    if self.cache.store(&uid, mtime, size, &bytes).is_ok() {
-                        count += 1;
-                    }
-                }
-                Err(e) => warn!(%uid, error = %e, "pin subtree: download failed"),
-            }
-        }
-        Ok(count)
+        Ok(files)
     }
 
     /// Fetch a thumbnail of `ttype` for the file at `ino`, served from the cache
@@ -4326,9 +4415,15 @@ impl Core {
         if self.thumbnail_misses.lock().remote_contains(&key, mtime) {
             return Ok(None);
         }
+        // A file manager asks for one per file in a folder, on the metadata
+        // workers. Offline, or on a stalled link, each one held a worker for
+        // the SDK's whole retry budget, and every cold lookup, create and
+        // rename on the mount queued behind them (`docs/BUGS.md` B220).
+        if !self.is_online() {
+            return Ok(None);
+        }
         let bytes = self
-            .rt
-            .block_on(self.client.download_thumbnail(&uid, ttype))
+            .block_on_bounded(self.client.download_thumbnail(&uid, ttype))
             .map_err(|e| {
                 warn!(%uid, error = %e, "download thumbnail failed");
                 Errno::EIO
@@ -4348,6 +4443,8 @@ impl Core {
 
     /// Unpin the node at `rel`, evicting its cached content. For a folder, also
     /// evicts every descendant's cached blob (the subtree is no longer kept).
+    /// A node kept only because a folder above it is pinned is refused: there
+    /// is no pin of its own to remove, and it would stay kept all the same.
     fn unpin(&self, rel: &Path) -> CoreResult<String> {
         let (ino, uid) = self.resolve(rel)?;
         let (name, is_folder) = {
@@ -4357,14 +4454,24 @@ impl Core {
                 .map(|e| (e.node.name.clone(), e.node.is_folder()))
                 .unwrap_or_default()
         };
+        if self.pinned_by_folder(ino) {
+            return Err(CoreError::conflict(format!(
+                "{name} is kept offline because a folder above it is; unpin that folder instead"
+            )));
+        }
         self.cache
             .remove_pin(&uid)
             .map_err(|e| CoreError::from_api(&e, "unpin"))?;
         // A recursively-pinned folder's descendants were eviction-exempt; now
         // that the pin is gone, reclaim their blobs eagerly instead of waiting
-        // for budget pressure. Descendants come from the DB node tree.
+        // for budget pressure. Descendants come from the DB node tree. One
+        // pinned on its own, or under a pinned subfolder, is still kept.
         if is_folder && let Ok(uids) = self.db.descendants(&uid.to_string()) {
+            let still_pinned = self.pinned_set();
             for s in uids {
+                if still_pinned.contains(&s) {
+                    continue;
+                }
                 if let Some(u) = parse_uid(&s) {
                     self.cache.evict(&u);
                     self.evict_reader(&u);
@@ -4374,6 +4481,20 @@ impl Core {
         Ok(name)
     }
 
+    /// Whether the node at `ino` is kept offline because a folder above it is
+    /// pinned, whether or not it is also pinned on its own.
+    fn pinned_by_folder(&self, ino: u64) -> bool {
+        let parent = {
+            let st = self.state();
+            st.entries
+                .get(&ino)
+                .filter(|e| e.parent != ino)
+                .and_then(|e| st.entries.get(&e.parent))
+                .map(|p| p.uid.clone())
+        };
+        parent.is_some_and(|uid| self.cache.is_pinned(&uid))
+    }
+
     /// A Photos API handle sharing this Core's Drive client and session, so it
     /// reuses the daemon's single authenticated session rather than logging in
     /// again (Proton refresh tokens are single-use). Cheap — the Drive client
@@ -4386,10 +4507,13 @@ impl Core {
     /// the same lazy remote enumeration `readdir` uses, projected into
     /// serializable [`DirEntry`]s (with per-file pin state).
     fn list_dir(&self, rel: &Path) -> CoreResult<Vec<DirEntry>> {
-        let (ino, _uid) = self.resolve(rel)?;
+        let (ino, uid) = self.resolve(rel)?;
         self.ensure_children(ino)
             .map_err(|e| self.errno_error(e, "enumerate"))?;
         self.settle_listing_sizes(ino);
+        // Every entry shares this folder as its parent, so one lookup says
+        // whether they are all kept through it.
+        let pinned_by_folder = self.cache.is_pinned(&uid);
         // Snapshot the listing, then drop the lock before touching the on-disk
         // pin registry so a slow disk read doesn't block FUSE metadata ops.
         let rows: Vec<(String, bool, u64, i64, NodeUid, u64)> = {
@@ -4421,7 +4545,8 @@ impl Core {
                 is_dir,
                 size,
                 modified,
-                pinned: self.cache.is_pinned(&uid),
+                pinned: pinned_by_folder || self.cache.is_pinned(&uid),
+                pinned_by_folder,
                 cached: !is_dir && self.cache.is_cached(&uid, modified, size),
                 uid: uid.to_string(),
                 // Listing entries live in the requested dir; the caller derives
@@ -5088,6 +5213,133 @@ impl Core {
         Ok(name)
     }
 
+    /// Copy a file or folder into `new_parent_rel` on Proton Drive, which copies
+    /// the content there: nothing is downloaded or uploaded. Both paths are
+    /// mountpoint-relative. A name already taken in the folder gets the next
+    /// free ` (n)` suffix. Returns the copy's name.
+    ///
+    /// Drive copies what it holds, so the copy is refused offline and while the
+    /// mount still owes Drive part of it: a node or folder only queued locally,
+    /// a file with a queued upload or unsaved writes, or — for a folder, whose
+    /// queued changes could sit anywhere below it — any queued op at all.
+    fn copy_to(&self, rel: &Path, new_parent_rel: &Path) -> CoreResult<String> {
+        let (ino, uid) = self.resolve(rel)?;
+        let (pino, new_parent_uid) = self
+            .resolve_path(new_parent_rel)
+            .map_err(|e| self.errno_error(e, "resolve new parent"))?;
+        self.ensure_children(pino)
+            .map_err(|e| self.errno_error(e, "enumerate"))?;
+        self.require_uid_writable(&new_parent_uid)
+            .map_err(|error| self.errno_error(error, "copy access"))?;
+        let (name, is_folder, unsaved) = {
+            let st = self.state();
+            let entry = st
+                .entries
+                .get(&ino)
+                .ok_or_else(|| CoreError::not_found(format!("{} is gone", rel.display())))?;
+            // Unsaved writes, or a release still queueing them, to the file or,
+            // for a folder, to any file below it.
+            let unsaved = st
+                .active_writes
+                .iter()
+                .filter(|(_, w)| w.dirty)
+                .map(|(&open, _)| open)
+                .chain(st.releasing.iter().copied())
+                .any(|open| relocate::ino_is_under(&st, open, ino));
+            (entry.node.name.clone(), entry.node.is_folder(), unsaved)
+        };
+        // Unlike a move, a copy cannot wait in the queue: it needs the node as
+        // Drive has it, so it goes now or not at all, local-first or not.
+        if !self.is_online() {
+            return Err(CoreError::offline());
+        }
+        let owed = unsaved
+            || is_local_uid(&uid)
+            || is_local_uid(&new_parent_uid)
+            || self.db.has_any_op(&uid.to_string()).unwrap_or(true)
+            || (is_folder
+                && self
+                    .db
+                    .pending_op_counts()
+                    .map(|counts| counts.uploads + counts.changes > 0)
+                    .unwrap_or(true));
+        if owed {
+            return Err(CoreError::conflict(format!(
+                "{name} has changes that have not reached Proton Drive yet; \
+                 copy it once they have synced"
+            )));
+        }
+        let target = if is_folder {
+            AvailableNameTarget::Folder
+        } else {
+            AvailableNameTarget::File
+        };
+        let copy_name = self
+            .rt
+            .block_on(
+                self.drive
+                    .get_available_name(&new_parent_uid, &name, target),
+            )
+            .map_err(|e| CoreError::from_api(&e, "copy"))?;
+        let new_uid = self
+            .rt
+            .block_on(
+                self.drive
+                    .copy_node(&uid, &new_parent_uid, Some(&copy_name)),
+            )
+            .map_err(|e| CoreError::from_api(&e, "copy"))?;
+        let node = self
+            .fetch_minted_node(&new_uid, &copy_name)
+            .ok_or_else(|| minted_but_unlisted(&copy_name))?;
+        let mut st = self.state();
+        let copy_ino = st.intern(pino, node);
+        if let Some(kids) = st.children.get_mut(&pino)
+            && !kids.contains(&copy_ino)
+        {
+            kids.push(copy_ino);
+        }
+        drop(st);
+        self.flush_access_changes();
+        Ok(copy_name)
+    }
+
+    /// What the folder at `rel` holds on Proton Drive: bytes on storage and the
+    /// number of items below it. Drive adds it up, so nothing is listed here;
+    /// trashed items count, and the bytes are encrypted ones.
+    pub(crate) fn folder_size(&self, rel: &Path) -> CoreResult<proton_drive_rs::FolderSize> {
+        let (ino, uid) = self.resolve(rel)?;
+        let is_folder = self
+            .state()
+            .entries
+            .get(&ino)
+            .is_some_and(|entry| entry.node.is_folder());
+        if !is_folder {
+            return Err(CoreError::invalid(format!(
+                "{} is not a folder",
+                rel.display()
+            )));
+        }
+        self.folder_size_for_uid(&uid)
+    }
+
+    /// [`Core::folder_size`] for a folder addressed through any daemon location.
+    pub(crate) fn folder_size_by_uid(&self, uid: &str) -> CoreResult<proton_drive_rs::FolderSize> {
+        let uid = self.resolve_anywhere(uid)?;
+        self.folder_size_for_uid(&uid)
+    }
+
+    fn folder_size_for_uid(&self, uid: &NodeUid) -> CoreResult<proton_drive_rs::FolderSize> {
+        if is_local_uid(uid) {
+            return Err(CoreError::conflict("the folder is not on Proton Drive yet"));
+        }
+        if !self.is_online() {
+            return Err(CoreError::offline());
+        }
+        self.rt
+            .block_on(self.client.get_folder_size(uid))
+            .map_err(|e| CoreError::from_api(&e, "folder size"))
+    }
+
     /// Trash a file or folder. `rel` is mountpoint-relative. Forgets the node,
     /// evicts any cached content, and invalidates the parent listing.
     fn delete(&self, rel: &Path) -> CoreResult<String> {
@@ -5136,9 +5388,12 @@ impl Core {
     /// `unlink` under an open handle. Its queued ops go now, or the drain would
     /// upload to the node after it was trashed (`docs/BUGS.md` B106).
     fn remove_replaced(&self, ino: u64, uid: &NodeUid, name: &str) -> Result<(), Errno> {
+        // Asked under the uid the tree has now: a landed create's real uid is
+        // not in the tree yet (`docs/BUGS.md` B257).
+        let open = self.is_open_anywhere(uid);
         let landed;
         let uid = if is_local_uid(uid) {
-            if self.is_open_anywhere(uid) {
+            if open {
                 self.withdraw_queued_ops(uid)?;
             } else {
                 self.discard_queued_ops(uid)?;
@@ -5163,7 +5418,7 @@ impl Core {
         // Local-first or offline, or the network goes away under the call:
         // queue the trash. The rename that follows queues as well, behind it.
         if !self.sends_inline() {
-            return self.queue_trash(uid, name);
+            return self.queue_trash(uid, name, open);
         }
         self.require_uid_writable(uid)?;
         if let Err(e) = self
@@ -5171,7 +5426,7 @@ impl Core {
             .and_then(batch::into_unit)
         {
             if self.lost_link(&e, "trash a replaced node") {
-                return self.queue_trash(uid, name);
+                return self.queue_trash(uid, name, open);
             }
             error!(%uid, name, error = %e, "trashing the node a rename replaces failed");
             self.log_activity(ActivityKind::Trash, name, e.to_string(), false);
@@ -5313,6 +5568,7 @@ impl Core {
                 // A trashed node can't be pinned or served from the mount, so its
                 // content is never current cache: report neither.
                 pinned: false,
+                pinned_by_folder: false,
                 cached: false,
                 uid: item.uid,
                 path: String::new(),
@@ -5743,6 +5999,7 @@ impl Core {
         if let Some(p) = self.sync_progress.lock().get_mut(&folder_id) {
             f(p);
         }
+        self.sync_engine.moved();
     }
 
     /// Set the number of items the scan expects to check, from the size of the
@@ -6046,11 +6303,61 @@ fn is_gone(e: &(dyn std::error::Error + 'static)) -> bool {
 /// (`sync.rs`, `conflict_path`), so the two halves of the product name the same
 /// situation the same way and a user only has to learn it once.
 fn conflict_name(name: &str, stamp: i64) -> String {
+    conflict_name_as(name, conflict_label(), stamp)
+}
+
+/// [`conflict_name`] with the machine's label given.
+fn conflict_name_as(name: &str, label: &str, stamp: i64) -> String {
     let path = Path::new(name);
     let stem = path.file_stem().and_then(|s| s.to_str()).unwrap_or(name);
+    let tag = conflict_tag(label, stamp, 0);
     match path.extension().and_then(|s| s.to_str()) {
-        Some(ext) => format!("{stem} (sync-conflict {stamp}).{ext}"),
-        None => format!("{stem} (sync-conflict {stamp})"),
+        Some(ext) => format!("{stem} (sync-conflict {tag}).{ext}"),
+        None => format!("{stem} (sync-conflict {tag})"),
+    }
+}
+
+/// This machine's name as its conflict copies carry it (`docs/BUGS.md` B251).
+///
+/// Two computers syncing one folder that each keep a copy of the same file in
+/// the same second would otherwise make the same name on Drive, and nobody
+/// could tell which computer a copy came from. Read once, from the hostname.
+fn conflict_label() -> &'static str {
+    static LABEL: OnceLock<String> = OnceLock::new();
+    LABEL.get_or_init(|| conflict_label_of(&this_hostname()))
+}
+
+/// `host` as one token: anything but ASCII letters, digits, `-`, `_` and `.`
+/// becomes `-`, so the label holds no space for `conflict_base_name` to trip
+/// on and no `/` or `)` to break the name.
+fn conflict_label_of(host: &str) -> String {
+    let label: String = host
+        .chars()
+        .take(32)
+        .map(|c| {
+            if c.is_ascii_alphanumeric() || matches!(c, '-' | '_' | '.') {
+                c
+            } else {
+                '-'
+            }
+        })
+        .collect();
+    label.trim_matches('-').to_string()
+}
+
+/// The inside of a conflict copy's marker: `<label> <stamp>`, with `-<n>`
+/// when an earlier copy already holds that name. Without a label it is the
+/// bare stamp that copies had before B251.
+fn conflict_tag(label: &str, stamp: i64, suffix: u32) -> String {
+    let suffix = if suffix == 0 {
+        String::new()
+    } else {
+        format!("-{suffix}")
+    };
+    if label.is_empty() {
+        format!("{stamp}{suffix}")
+    } else {
+        format!("{label} {stamp}{suffix}")
     }
 }
 
@@ -6660,7 +6967,27 @@ fn fuse_name(name: &OsStr) -> Result<String, Errno> {
     name.to_str().map(str::to_owned).ok_or(Errno::EILSEQ)
 }
 
+/// Whether a decrypted remote name can stand as one local path component.
+///
+/// Drive checks names only when a client creates or renames a node, and only
+/// for length, so a name made by another client, or by a server that should
+/// not be trusted, can hold anything. Joined onto a local path, a `/` or a `..`
+/// in it walks out of the folder it belongs to, and the mirror engine would
+/// then write or delete outside the sync root. In the mount, the kernel fails
+/// the whole listing with EIO on a single such name (`docs/BUGS.md` B215).
+pub(crate) fn remote_name_is_safe(name: &str) -> bool {
+    !name.is_empty()
+        && name != "."
+        && name != ".."
+        && name.len() <= 255
+        && !name.contains(['/', '\0'])
+}
+
 fn node_visible(node: &Node, folder_uid: &NodeUid, hidden: &HashSet<NodeUid>) -> bool {
+    if !remote_name_is_safe(&node.name) {
+        warn!(uid = %node.uid, "a remote name cannot be a local file name; leaving it out");
+        return false;
+    }
     !node.trashed && node.uid != *folder_uid && !hidden.contains(&node.uid)
 }
 
@@ -6996,13 +7323,15 @@ mod size_upgrade_tests {
     fn a_listing_waits_for_the_whole_size_batch_but_not_forever() {
         let slot = Arc::new(SizeUpgrade::default());
         let worker = slot.clone();
+        // Read before the spawn: the worker's sleeps can start before this
+        // thread runs again, which made the bound below fail on a busy runner.
+        let started = Instant::now();
         let t = std::thread::spawn(move || {
             std::thread::sleep(Duration::from_millis(30));
             worker.chunk_done();
             std::thread::sleep(Duration::from_millis(60));
             worker.finish();
         });
-        let started = Instant::now();
         slot.wait_finished(started + Duration::from_secs(5));
         // Past the first chunk, up to the end of the batch.
         assert!(started.elapsed() >= Duration::from_millis(90));
@@ -7409,14 +7738,15 @@ mod tests {
     use super::{
         Access, AccessFlags, Errno, HashMap, Intervals, PendingRevision, RootListingSnapshot,
         SELF_CHANGE_TTL_MS, ShareId, SharedWithMeItem, StateRegistry, VirtualRootPlan,
-        accepted_share_provenance, conflict_name, copy_pending_for_truncate, expand_restore,
-        first_seen_in_trash, fuse_name, is_stale_mount, node_visible, note_self_change,
-        off_the_runtime, orphan_past_retention, parse_node_uid, prepare_shared_roots,
-        preserve_on_access_denied, publish_virtual_root_in_listing,
-        reconcile_virtual_root_in_listing, release_can_discard_unlinked,
-        release_must_retain_queued_trash, release_unlinked_entry, rename_needs_queue,
-        require_node_parent_access, require_rename_access, resolve_anywhere_with,
-        shared_with_me_uid, take_self_change, uid_write_authority, virtual_node,
+        accepted_share_provenance, conflict_label, conflict_label_of, conflict_name,
+        conflict_name_as, copy_pending_for_truncate, expand_restore, first_seen_in_trash,
+        fuse_name, is_stale_mount, node_visible, note_self_change, off_the_runtime,
+        orphan_past_retention, parse_node_uid, prepare_shared_roots, preserve_on_access_denied,
+        publish_virtual_root_in_listing, reconcile_virtual_root_in_listing,
+        release_can_discard_unlinked, release_must_retain_queued_trash, release_unlinked_entry,
+        rename_needs_queue, require_node_parent_access, require_rename_access,
+        resolve_anywhere_with, shared_with_me_uid, take_self_change, uid_write_authority,
+        virtual_node,
     };
     use super::{Db, WriteAuthority};
     use std::time::Duration;
@@ -8371,15 +8701,38 @@ mod tests {
     #[test]
     fn conflict_name_keeps_the_extension() {
         assert_eq!(
-            conflict_name("notes.txt", 1700),
-            "notes (sync-conflict 1700).txt"
+            conflict_name_as("notes.txt", "laptop", 1700),
+            "notes (sync-conflict laptop 1700).txt"
         );
-        assert_eq!(conflict_name("README", 42), "README (sync-conflict 42)");
         assert_eq!(
-            conflict_name("archive.tar.gz", 7),
-            "archive.tar (sync-conflict 7).gz",
+            conflict_name_as("README", "laptop", 42),
+            "README (sync-conflict laptop 42)"
+        );
+        assert_eq!(
+            conflict_name_as("archive.tar.gz", "laptop", 7),
+            "archive.tar (sync-conflict laptop 7).gz",
             "only the last extension is one, as everywhere else"
         );
+        assert_eq!(
+            conflict_name_as("notes.txt", "", 1700),
+            "notes (sync-conflict 1700).txt"
+        );
+        assert_eq!(
+            conflict_name("notes.txt", 1700),
+            conflict_name_as("notes.txt", conflict_label(), 1700)
+        );
+    }
+
+    /// A hostname goes into a file name, so it is cut down to one safe token
+    /// (B251).
+    #[test]
+    fn a_hostname_becomes_one_safe_token() {
+        assert_eq!(conflict_label_of("laptop"), "laptop");
+        assert_eq!(conflict_label_of("my-pc.local"), "my-pc.local");
+        assert_eq!(conflict_label_of("Linux device"), "Linux-device");
+        assert_eq!(conflict_label_of("a/b) c"), "a-b--c");
+        assert_eq!(conflict_label_of("  "), "");
+        assert_eq!(conflict_label_of(&"x".repeat(40)).len(), 32);
     }
 
     #[test]
@@ -8571,6 +8924,28 @@ mod tests {
         ));
     }
 
+    #[test]
+    fn a_remote_name_that_is_not_one_path_component_is_left_out() {
+        let folder_uid = NodeUid::new(VolumeId::from("vol"), LinkId::from("folder"));
+        let none = std::collections::HashSet::new();
+        for name in [
+            "a/b",
+            "../../.bashrc",
+            "..",
+            ".",
+            "",
+            "a\0b",
+            &"x".repeat(256),
+        ] {
+            let node = node_helper("child", "folder", name, false);
+            assert!(!node_visible(&node, &folder_uid, &none), "{name:?}");
+        }
+        for name in [".hidden", "a..b", "unicodé-文件", &"x".repeat(255)] {
+            let node = node_helper("child", "folder", name, false);
+            assert!(node_visible(&node, &folder_uid, &none), "{name:?}");
+        }
+    }
+
     #[test]
     fn denied_queue_guard_preserves_accepted_bytes_and_pending_count() {
         use std::cell::Cell;
@@ -8891,7 +9266,7 @@ mod tests {
         assert!(!replaced.contains("st.forget(uid)"));
         assert_before(
             replaced,
-            "if self.is_open_anywhere(uid)",
+            "let open = self.is_open_anywhere(uid)",
             "self.discard_queued_ops(uid)",
         );
         assert_before(replaced, "if open_now", "self.cache.evict(uid)");
@@ -9076,6 +9451,32 @@ mod tests {
         assert!(online.contains("self.relist_offline_listings();"));
     }
 
+    #[test]
+    fn a_stale_shared_listing_is_fetched_off_the_dispatch_loop() {
+        // A resident listing that `list_children` would fetch again anyway
+        // must not be answered inline (B219).
+        let cached = function_source(include_str!("lib.rs"), "fn children_cached(");
+        assert!(cached.contains("SHARED_WITH_ME_SYNCED_MS"));
+        assert!(cached.contains("Self::shared_folder_freshness_key(&uid)"));
+        assert!(cached.contains("listing_needs_refresh("));
+        assert!(cached.contains("self.shared_listing_stale(&key)"));
+    }
+
+    #[test]
+    fn a_handler_does_not_wait_out_the_sdk_retry_budget() {
+        // Thumbnails, size upgrades and the share list held mount threads for
+        // minutes on a stalled link (B220).
+        let lib = include_str!("lib.rs");
+        let thumbnail = function_source(lib, "fn thumbnail(");
+        assert_before(thumbnail, "if !self.is_online()", "download_thumbnail");
+        assert!(thumbnail.contains(".block_on_bounded(self.client.download_thumbnail("));
+        let upgrade = function_source(lib, "fn run_size_upgrade(");
+        assert!(upgrade.contains("block_on_within(BATCH_CALL_TIMEOUT"));
+        let shared = function_source(lib, "fn ensure_shared_children(");
+        assert!(shared.contains("block_on_within(BATCH_CALL_TIMEOUT"));
+        assert!(!shared.contains("self.rt"));
+    }
+
     #[test]
     fn a_remote_read_gives_up_at_its_deadline() {
         // The SDK bounds requests, not reads; a stalled link held one `read`

crates/pdfs-fuse/src/link.rs

@@ -9,10 +9,11 @@
 //! queued path, and the probe thread here flips it back when Proton answers.
 
 use std::future::Future;
-use std::sync::atomic::Ordering;
+use std::sync::atomic::{AtomicBool, Ordering};
 use std::time::{Duration, Instant};
 
 use parking_lot::{Condvar, Mutex};
+use pdfs_core::error::session_revoked;
 use proton_drive_rs::proton_sdk::api::ResponseCode;
 use proton_drive_rs::proton_sdk::error::{ProtonApiError, ProtonError};
 use tracing::{debug, info, warn};
@@ -28,6 +29,13 @@ use crate::{Core, ONLINE_PROBE_MAX, ONLINE_PROBE_MIN};
 /// keep waiting for; queueing the change is the better answer.
 pub(crate) const INTERACTIVE_CALL_TIMEOUT: Duration = Duration::from_secs(20);
 
+/// How long a mount thread waits on a remote read that answers a batch: a
+/// chunk of file sizes, or the list of shares. Longer than an interactive call,
+/// since its answer grows with the batch, but well short of the SDK's own retry
+/// budget, which held a worker for minutes on a stalled link
+/// (`docs/BUGS.md` B220).
+pub(crate) const BATCH_CALL_TIMEOUT: Duration = Duration::from_secs(60);
+
 /// How long one probe may wait for an answer. A probe is a single small request,
 /// and a probe stuck in the SDK's retry budget would delay noticing the link is
 /// back by as long as it waits.
@@ -54,6 +62,26 @@ pub(crate) struct Link {
     changed: Condvar,
     /// Folders listed from the DB alone while offline, to relist once back.
     pub(crate) stale_listings: Mutex<std::collections::HashSet<u64>>,
+    /// Proton refused the session itself ([`session_revoked`]). The mount is
+    /// offline then, but no probe brings it back: only a new login does, and
+    /// that restarts the daemon. Read by front-ends through `Response::Status`,
+    /// so they can ask the user to sign in again rather than say "offline".
+    pub(crate) session_expired: AtomicBool,
+    /// Proton refused the session, but only because another process rotated
+    /// it (`pdfs unlock`): the keyring holds the live tokens. The mount loop
+    /// ends the mount for the daemon to mount again from the keyring.
+    pub(crate) resume_stored: AtomicBool,
+}
+
+impl Link {
+    /// The link of a mount that comes up with Proton refusing its session, or
+    /// not.
+    pub(crate) fn starting(session_expired: bool) -> Self {
+        Self {
+            session_expired: AtomicBool::new(session_expired),
+            ..Default::default()
+        }
+    }
 }
 
 /// Whether a failed call failed because Proton could not be reached, rather
@@ -91,10 +119,25 @@ pub(crate) fn no_answer(after: Duration) -> ProtonError {
 /// transfer that has stopped moving runs into it.
 const SLOWEST_UPLOAD: u64 = 32 * 1024;
 
+/// How many uploads can share the upload cap at once: one per drain worker
+/// and one per mirror sync task.
+const UPLOAD_SLOTS: u64 = (crate::DRAIN_WORKERS + crate::sync::SYNC_CONCURRENCY) as u64;
+
 /// How long an upload of `len` bytes may take before the link is treated as
 /// down: the budget of a metadata call, plus the bytes at [`SLOWEST_UPLOAD`].
-pub(crate) fn upload_deadline(len: u64) -> Duration {
-    INTERACTIVE_CALL_TIMEOUT + Duration::from_secs(len / SLOWEST_UPLOAD)
+///
+/// An upload cap of `cap` bytes per second (`0` for none) is shared by every
+/// upload running, so each may get as little as its share of it. Below
+/// [`SLOWEST_UPLOAD`] a share counts as the slowest rate instead: measured
+/// against the fixed rate, a large file under a low cap ran out of time on
+/// every attempt, took the mount offline each time, and started over from
+/// its first byte.
+pub(crate) fn upload_deadline(len: u64, cap: u64) -> Duration {
+    let slowest = match cap {
+        0 => SLOWEST_UPLOAD,
+        cap => SLOWEST_UPLOAD.min((cap / UPLOAD_SLOTS).max(1)),
+    };
+    INTERACTIVE_CALL_TIMEOUT + Duration::from_secs(len / slowest)
 }
 
 /// Run a remote call, giving up after [`INTERACTIVE_CALL_TIMEOUT`].
@@ -161,10 +204,20 @@ impl Core {
         self.rt.block_on(bounded_by(limit, call))
     }
 
+    /// Whether Proton refused the session itself, so nothing reaches it until
+    /// the user signs in again.
+    pub(crate) fn session_expired(&self) -> bool {
+        self.link.session_expired.load(Ordering::Relaxed)
+    }
+
     /// Report a failed remote call. Returns whether it failed for want of a
-    /// network, in which case the mount is now offline and the caller should
-    /// take its queued path instead of failing.
+    /// network, or of a session, in which case the mount is now offline and the
+    /// caller should take its queued path instead of failing.
     pub(crate) fn lost_link(&self, e: &ProtonError, what: &str) -> bool {
+        if session_revoked(e) {
+            self.mark_session_expired(what, e);
+            return true;
+        }
         if !is_network_error(e) {
             return false;
         }
@@ -172,6 +225,29 @@ impl Core {
         true
     }
 
+    /// Flip the mount offline for good: Proton refused the session, and only a
+    /// new login brings it back. Changes stay queued for the daemon that login
+    /// starts. Only the first caller logs it.
+    ///
+    /// Unless the keyring holds a newer session than the refused one: then
+    /// the mount ends, for the daemon to mount again on that one.
+    pub(crate) fn mark_session_expired(&self, what: &str, error: &dyn std::fmt::Display) {
+        if self.link.resume_stored.load(Ordering::Relaxed) {
+            return self.mark_offline(what, error);
+        }
+        if pdfs_core::auth::stored_session_is_newer() {
+            info!(during = what, %error,
+                  "Proton refused a session another process has since refreshed; resuming it");
+            self.link.resume_stored.store(true, Ordering::Relaxed);
+            return self.mark_offline(what, error);
+        }
+        if !self.link.session_expired.swap(true, Ordering::Relaxed) {
+            warn!(during = what, %error,
+                  "Proton refused the session; run `pdfs login` to sign in again");
+        }
+        self.mark_offline(what, error);
+    }
+
     /// Flip the mount offline and wake the probe. Only the first caller of an
     /// outage logs it; the rest are the same outage.
     pub(crate) fn mark_offline(&self, what: &str, error: &dyn std::fmt::Display) {
@@ -204,8 +280,9 @@ impl Core {
         self.relist_offline_listings();
         // Anything written while offline is queued and waiting on exactly this,
         // including ops that failed on the way down and are sitting out a
-        // backoff sized for a server that keeps refusing.
-        if let Err(e) = self.db.retry_failed_ops_now(crate::now_millis()) {
+        // backoff sized for a server that keeps refusing. Ops Drive refused
+        // keep theirs: the link was not why.
+        if let Err(e) = self.db.retry_unrefused_ops_now(crate::now_millis()) {
             warn!(error = %e, "moving backed-off ops up after a reconnect failed");
         }
         self.wake_drain();
@@ -276,6 +353,9 @@ impl Core {
 
     /// Probe until Proton answers, then flip the mount online. Returns `false`
     /// if the daemon is stopping.
+    ///
+    /// A refused session is not probed: every probe would be refused the same
+    /// way, forever (issue #35). The thread waits for the stop instead.
     fn probe_until_online(&self) -> bool {
         let started = self.link.lost_at.lock().unwrap_or_else(Instant::now);
         let mut delay = if started.elapsed() < YOUNG_OUTAGE {
@@ -287,6 +367,10 @@ impl Core {
             if !self.shutdown.sleep(delay) {
                 return false;
             }
+            if self.session_expired() {
+                delay = ONLINE_PROBE_MAX;
+                continue;
+            }
             let probe = self.rt.block_on(async {
                 match tokio::time::timeout(PROBE_TIMEOUT, self.drive.get_my_files_folder()).await {
                     Ok(result) => result,
@@ -308,6 +392,7 @@ impl Core {
                     self.mark_online();
                     return true;
                 }
+                Err(e) if session_revoked(&e) => self.mark_session_expired("online probe", &e),
                 Err(e) => {
                     debug!(error = %e, ?delay, "online probe failed; still offline");
                     delay = next_probe_delay(delay, started.elapsed());
@@ -341,13 +426,31 @@ mod tests {
 
     #[test]
     fn an_upload_gets_longer_the_bigger_it_is() {
-        assert_eq!(upload_deadline(0), INTERACTIVE_CALL_TIMEOUT);
+        assert_eq!(upload_deadline(0, 0), INTERACTIVE_CALL_TIMEOUT);
         assert_eq!(
-            upload_deadline(1 << 30),
+            upload_deadline(1 << 30, 0),
             INTERACTIVE_CALL_TIMEOUT + Duration::from_secs(32_768)
         );
     }
 
+    #[test]
+    fn an_upload_under_a_low_cap_gets_the_time_its_share_of_the_cap_needs() {
+        // A generous cap leaves the deadline as it was.
+        assert_eq!(
+            upload_deadline(1 << 30, 100 << 20),
+            upload_deadline(1 << 30, 0)
+        );
+        // 512 KiB/s shared by every upload slot is below the slowest rate.
+        let share = (512 << 10) / UPLOAD_SLOTS;
+        assert!(share < SLOWEST_UPLOAD);
+        assert_eq!(
+            upload_deadline(1 << 30, 512 << 10),
+            INTERACTIVE_CALL_TIMEOUT + Duration::from_secs((1 << 30) / share)
+        );
+        // A cap below one byte per slot still gives a finite deadline.
+        assert!(upload_deadline(1 << 20, 1) > upload_deadline(1 << 20, 512 << 10));
+    }
+
     #[test]
     fn a_call_past_its_deadline_reads_as_a_lost_link() {
         let rt = tokio::runtime::Builder::new_current_thread()

crates/pdfs-fuse/src/mount.rs

@@ -12,6 +12,10 @@ pub enum MountOutcome {
     /// The kernel mount ended on its own (e.g. an external `fusermount -u`).
     /// The caller may want to remount.
     Unmounted,
+    /// Proton refused the session, and the keyring holds a newer one: another
+    /// process (`pdfs unlock`) refreshed it, or a new login replaced it. We
+    /// unmounted ourselves; the caller should mount again, which resumes it.
+    ResumeStored,
 }
 
 /// Whether `path` is a mountpoint whose FUSE connection is dead — the state a
@@ -192,6 +196,29 @@ pub(super) fn clear_stale_mount(mountpoint: &Path) {
     }
 }
 
+/// Refuse to mount My files over a folder that already has files in it: FUSE
+/// would hide them, unsent and out of sight, until the service stops
+/// (`docs/BUGS.md` B277). Runs before the root fetch and before any worker
+/// starts, so a refusal costs nothing to retry.
+///
+/// A dead mount is cleared first, since it cannot be listed. One of this
+/// client's own live mounts is left to [`spawn_session`], which clears it as it
+/// always has; listing it would show Drive's files, not the folder's.
+pub(super) fn check_mountpoint(mountpoint: &Path) -> std::io::Result<()> {
+    if is_stale_mount(mountpoint) {
+        clear_stale_mount(mountpoint);
+    }
+    if pdfs_core::mountpoint::mounted_fs_type(mountpoint).as_deref()
+        == Some(pdfs_core::mountpoint::OWN_FS_TYPE)
+    {
+        return Ok(());
+    }
+    match pdfs_core::mountpoint::not_empty(mountpoint)? {
+        Some(found) => Err(std::io::Error::other(found)),
+        None => Ok(()),
+    }
+}
+
 /// `sync_state` key holding the uid of the My Files root, so a later run can
 /// recover it from `nodes` without the API.
 const ROOT_UID_KEY: &str = "root_uid";
@@ -210,30 +237,60 @@ fn fetch_or_recall_root(
     drive: &dyn DriveApi,
     rt: &tokio::runtime::Handle,
     db: &Db,
-) -> std::io::Result<(Node, bool)> {
+) -> std::io::Result<(Node, Start)> {
     let err = match rt.block_on(drive.get_my_files_folder()) {
         Ok(root) => {
             if let Err(e) = db.set_state_str(ROOT_UID_KEY, &root.uid.to_string()) {
                 warn!(error = %e, "persist root uid failed");
             }
-            return Ok((root, true));
+            return Ok((root, Start::Online));
         }
         Err(e) => e,
     };
+    // Still mounted from the cache, so cached files stay readable and changes
+    // queue for the daemon the next login starts.
+    let start = if pdfs_core::error::session_revoked(&err) {
+        Start::SessionExpired
+    } else {
+        Start::Offline
+    };
+    if start == Start::SessionExpired && pdfs_core::auth::stored_session_is_newer() {
+        return Err(std::io::Error::other(format!(
+            "Proton refused a session another process has since refreshed ({err}); resuming it"
+        )));
+    }
     let cached = db
         .state_str(ROOT_UID_KEY)
         .ok()
         .flatten()
         .and_then(|uid| db.node_by_uid(&uid).ok().flatten());
     match cached {
+        Some(root) if start == Start::SessionExpired => {
+            warn!(error = %err,
+                  "Proton refused the session; mounting from cache until `pdfs login`");
+            Ok((root, start))
+        }
         Some(root) => {
             warn!(error = %err, "fetch My Files root failed; mounting from cache (offline)");
-            Ok((root, false))
+            Ok((root, start))
         }
+        None if start == Start::SessionExpired => Err(std::io::Error::other(format!(
+            "Proton refused the session ({err}); run `pdfs login`"
+        ))),
         None => Err(std::io::Error::other(format!("fetch My Files root: {err}"))),
     }
 }
 
+/// How a mount comes up, from what fetching its root said.
+#[derive(Clone, Copy, PartialEq, Eq)]
+enum Start {
+    Online,
+    /// Proton could not be reached: serve the cache and probe for the link.
+    Offline,
+    /// Proton refused the session: serve the cache until a new login.
+    SessionExpired,
+}
+
 /// Per-mount settings resolved from [`pdfs_core::config::AppConfig`] by the
 /// caller, so `mount` itself never reads config or the environment.
 pub struct MountOptions {
@@ -393,7 +450,9 @@ pub(crate) fn mount_with(
     // Start the uptime clock here rather than at the first `pdfs diagnostics`,
     // so the age it reports is the daemon's own.
     super::diagnostics::start_clock();
-    let (root, online) = fetch_or_recall_root(drive.as_ref(), &rt, &db)?;
+    check_mountpoint(mountpoint)?;
+    let (root, start) = fetch_or_recall_root(drive.as_ref(), &rt, &db)?;
+    let online = start == Start::Online;
     let scope = root.tree_event_scope_id();
     db.mount_upsert_my_files(&mountpoint.to_string_lossy(), &root.uid.to_string(), None)
         .map_err(|error| std::io::Error::other(format!("project My Files mount: {error}")))?;
@@ -429,7 +488,7 @@ pub(crate) fn mount_with(
         shared_generation: Arc::new(AtomicU64::new(0)),
         shared_refresh_deadlines: Arc::new(Mutex::new(SharedRefreshDeadlines::default())),
         online: Arc::new(AtomicBool::new(online)),
-        link: Arc::new(Default::default()),
+        link: Arc::new(link::Link::starting(start == Start::SessionExpired)),
         sync_paused_until: Arc::new(AtomicI64::new(paused_until)),
         pending: Arc::new(Mutex::new(HashMap::new())),
         hidden: Arc::new(Mutex::new(HashSet::new())),
@@ -472,9 +531,11 @@ pub(crate) fn mount_with(
         events: Arc::new(Default::default()),
         indexing: Arc::new(AtomicBool::new(false)),
         sync_progress: Arc::new(Mutex::new(HashMap::new())),
+        sync_engine: Arc::default(),
         sync_tx,
         mounts: Arc::new(Mutex::new(SecondaryMountRegistry::default())),
         sync_locks: Arc::new(Mutex::new(HashMap::new())),
+        sync_unscanned: Arc::new(Mutex::new(HashMap::new())),
         states: Arc::new(StateRegistry::default()),
     };
     // Before anything can queue work against it: the drain thread below reaches
@@ -504,12 +565,11 @@ pub(crate) fn mount_with(
     // and sweeps all operating on a mount that no longer exists (`docs/BUGS.md` B44).
     let mut workers: Vec<std::thread::JoinHandle<()>> = Vec::new();
     for worker in 0..DRAIN_WORKERS {
-        let core = core.clone();
-        workers.push(
-            std::thread::Builder::new()
-                .name(format!("pdfs-drain-{worker}"))
-                .spawn(move || core.run_pending_drain(worker == 0))?,
-        );
+        let drain_core = core.clone();
+        let spawned = std::thread::Builder::new()
+            .name(format!("pdfs-drain-{worker}"))
+            .spawn(move || drain_core.run_pending_drain(worker == 0));
+        keep_or_abandon(&core, control_socket, &mut workers, spawned)?;
     }
 
     // Start the folder-sync engine. It watches every mirror folder, polls the
@@ -529,24 +589,22 @@ pub(crate) fn mount_with(
         info!("conflict sweep disabled by configuration");
     } else {
         info!(mode = ?sweep_mode, "conflict sweep enabled");
-        let core = core.clone();
-        workers.push(
-            std::thread::Builder::new()
-                .name("pdfs-conflict-sweep".into())
-                .spawn(move || core.run_conflict_sweep_loop())?,
-        );
+        let sweep_core = core.clone();
+        let spawned = std::thread::Builder::new()
+            .name("pdfs-conflict-sweep".into())
+            .spawn(move || sweep_core.run_conflict_sweep_loop());
+        keep_or_abandon(&core, control_socket, &mut workers, spawned)?;
     }
 
     // Watch the link for the life of the mount: a mount from the cache waits for
     // the network to come back, and an online one can lose it at any moment and
     // must notice it coming back just the same.
     {
-        let core = core.clone();
-        workers.push(
-            std::thread::Builder::new()
-                .name("pdfs-online-probe".into())
-                .spawn(move || core.run_online_probe())?,
-        );
+        let probe_core = core.clone();
+        let spawned = std::thread::Builder::new()
+            .name("pdfs-online-probe".into())
+            .spawn(move || probe_core.run_online_probe());
+        keep_or_abandon(&core, control_socket, &mut workers, spawned)?;
     }
 
     // Keep the launcher prompt's "This computer" index fresh. Its own thread:
@@ -557,11 +615,10 @@ pub(crate) fn mount_with(
         let transfers = core.transfers.clone();
         let mountpoint = mountpoint.to_path_buf();
         let shutdown = core.shutdown.clone();
-        workers.push(
-            std::thread::Builder::new()
-                .name("pdfs-localindex".into())
-                .spawn(move || run_local_index(db, indexing, transfers, mountpoint, shutdown))?,
-        );
+        let spawned = std::thread::Builder::new()
+            .name("pdfs-localindex".into())
+            .spawn(move || run_local_index(db, indexing, transfers, mountpoint, shutdown));
+        keep_or_abandon(&core, control_socket, &mut workers, spawned)?;
     }
 
     // Bind the control socket before the FUSE session takes over the thread. A
@@ -570,12 +627,18 @@ pub(crate) fn mount_with(
     let old_umask = unsafe { libc::umask(0o77) };
     let listener_res = UnixListener::bind(control_socket);
     unsafe { libc::umask(old_umask) };
-    let listener = listener_res?;
+    let listener = match listener_res {
+        Ok(listener) => listener,
+        Err(error) => {
+            abandon_workers(&core, control_socket, workers);
+            return Err(error);
+        }
+    };
     // Owner-only before anything can connect: a peer on this socket commands the
     // daemon's authenticated session without a credential of its own (B6).
     if let Err(e) = pdfs_core::config::restrict_socket(control_socket) {
         error!(error = %e, "cannot restrict control socket permissions; refusing to serve");
-        let _ = std::fs::remove_file(control_socket);
+        abandon_workers(&core, control_socket, workers);
         return Err(std::io::Error::other(format!(
             "control socket permissions: {e}"
         )));
@@ -586,7 +649,7 @@ pub(crate) fn mount_with(
     let bg = match spawn_session(&core, mountpoint, root) {
         Ok(session) => session,
         Err(error) => {
-            let _ = std::fs::remove_file(control_socket);
+            abandon_workers(&core, control_socket, workers);
             return Err(error);
         }
     };
@@ -606,7 +669,7 @@ pub(crate) fn mount_with(
             Err(error) => {
                 // A failure here abandons the mount, so the background threads
                 // started above have to be told to stop with it.
-                stop_workers(&core, control_socket, workers);
+                abandon_workers(&core, control_socket, workers);
                 let secondaries = core.mounts.lock().close_and_drain();
                 for (id, mount) in secondaries {
                     if let Err(unmount_error) = mount.teardown() {
@@ -656,8 +719,12 @@ pub(crate) fn mount_with(
         }
     }
     // The mount is live and the control socket answers: this is the moment the
-    // unit is actually usable, which is what `Type=notify` reports.
+    // unit is actually usable, which is what `Type=notify` reports. Whatever
+    // failure an earlier attempt recorded for the front ends is over.
     systemd::ready();
+    if let Some(state_dir) = control_socket.parent() {
+        pdfs_core::mountfail::clear(state_dir);
+    }
 
     // Re-establish on-demand mounts only after the primary session is live.
     // Keep the worker so shutdown can close publication, wait for any in-flight
@@ -718,6 +785,18 @@ pub(crate) fn mount_with(
                 }
                 break MountOutcome::Shutdown;
             }
+            Err(std::sync::mpsc::RecvTimeoutError::Timeout)
+                if core.link.resume_stored.load(Ordering::Relaxed) =>
+            {
+                info!("unmounting to resume the stored session");
+                core.mounts.lock().close();
+                if let Err(e) = teardown_session(&core.session_live, || {
+                    umount_session_unblocked(bg, main_conn)
+                }) {
+                    warn!(error = %e, "umount_and_join failed");
+                }
+                break MountOutcome::ResumeStored;
+            }
             Err(std::sync::mpsc::RecvTimeoutError::Timeout) => {
                 if bg.guard.is_finished() {
                     info!("mount ended externally");
@@ -811,6 +890,43 @@ fn stop_workers(core: &Core, control_socket: &Path, workers: Vec<std::thread::Jo
     // Say so before the joins: a teardown that takes a while must not be read as
     // a missed watchdog ping and turned into a kill.
     systemd::stopping();
+    halt_workers(core, control_socket, workers);
+}
+
+/// Stop the threads a mount attempt started before it failed.
+///
+/// The early returns used to leave them running: every retry started another
+/// set beside the last one's, and their `Core` kept the database open, so the
+/// next attempt could fail on its lock instead of the real error
+/// (`docs/BUGS.md` B264). Unlike [`stop_workers`] this does not tell systemd
+/// the daemon is stopping, because it is about to try again, and a manager
+/// told so would wait for the process to exit and then kill it.
+fn abandon_workers(core: &Core, control_socket: &Path, workers: Vec<std::thread::JoinHandle<()>>) {
+    halt_workers(core, control_socket, workers);
+}
+
+/// Keep a worker the mount just spawned, or, if the spawn failed, stop the
+/// ones already running and hand the error back.
+fn keep_or_abandon(
+    core: &Core,
+    control_socket: &Path,
+    workers: &mut Vec<std::thread::JoinHandle<()>>,
+    spawned: std::io::Result<std::thread::JoinHandle<()>>,
+) -> std::io::Result<()> {
+    match spawned {
+        Ok(handle) => {
+            workers.push(handle);
+            Ok(())
+        }
+        Err(error) => {
+            abandon_workers(core, control_socket, std::mem::take(workers));
+            Err(error)
+        }
+    }
+}
+
+/// Signal every worker to stop, then join them up to [`WORKER_JOIN_DEADLINE`].
+fn halt_workers(core: &Core, control_socket: &Path, workers: Vec<std::thread::JoinHandle<()>>) {
     core.shutdown.stop();
     core.wake_drain();
     let _ = core.sync_tx.send(sync::SyncMsg::Stop);

crates/pdfs-fuse/src/photos.rs

@@ -226,11 +226,7 @@ fn scale_thumbnail_with_exiftool(
     exiftool: &OsStr,
     timeout: Duration,
 ) -> ScaleAttempt {
-    let direct = image::ImageReader::new(std::io::Cursor::new(bytes))
-        .with_guessed_format()
-        .ok()
-        .and_then(|reader| reader.decode().ok());
-    let image = match direct {
+    let image = match decode_upright(bytes) {
         Some(image) => image,
         None if is_raw_image_name(name) => {
             let (preview, orientation) =
@@ -256,6 +252,27 @@ fn scale_thumbnail_with_exiftool(
     encode_thumb(&image)
 }
 
+/// Decode `bytes` and turn the picture the way its EXIF orientation says.
+///
+/// `ImageReader::decode` does not: a phone stores a portrait photo as landscape
+/// pixels plus an orientation tag, so every such thumbnail came out on its
+/// side, and the drain uploaded it to Drive that way for every client to show
+/// (`docs/BUGS.md` B226).
+fn decode_upright(bytes: &[u8]) -> Option<image::DynamicImage> {
+    use image::ImageDecoder as _;
+    let mut decoder = image::ImageReader::new(std::io::Cursor::new(bytes))
+        .with_guessed_format()
+        .ok()?
+        .into_decoder()
+        .ok()?;
+    let orientation = decoder
+        .orientation()
+        .unwrap_or(image::metadata::Orientation::NoTransforms);
+    let mut image = image::DynamicImage::from_decoder(decoder).ok()?;
+    image.apply_orientation(orientation);
+    Some(image)
+}
+
 /// Shrink a decoded image to a [`THUMB_EDGE`] JPEG, keeping its aspect ratio.
 fn encode_thumb(image: &image::DynamicImage) -> ScaleAttempt {
     let (width, height) = (image.width(), image.height());
@@ -417,6 +434,16 @@ fn exiftool_query(
     serde_json::from_slice(&output).map_err(|_| RawPreviewUnavailable)
 }
 
+/// Whether [`upload_thumbnails`] can make a thumbnail for a file `name` of
+/// `size` bytes, asked before the file is on disk: an image small enough to
+/// decode, or a video while ffmpeg is installed.
+pub(crate) fn can_make_thumbnail(name: &str, size: u64) -> bool {
+    if is_video_name(name) {
+        return ffmpeg_available();
+    }
+    is_thumbnail_image_name(name) && size <= UPLOAD_IMAGE_MAX_BYTES
+}
+
 /// Whether `name` is a video, whose thumbnail is a frame ffmpeg grabs rather
 /// than a picture the image decoder can scale.
 fn is_video_name(name: &str) -> bool {
@@ -1317,7 +1344,7 @@ impl Core {
         let next = |current| if current == u64::MAX { 1 } else { current + 1 };
         let previous = self
             .file_thumb_generation
-            .fetch_update(Ordering::SeqCst, Ordering::SeqCst, |current| {
+            .try_update(Ordering::SeqCst, Ordering::SeqCst, |current| {
                 Some(next(current))
             })
             .expect("generation update always succeeds");
@@ -2092,9 +2119,10 @@ impl Core {
 #[cfg(test)]
 mod thumb_tests {
     use super::{
-        RawTempFile, ScaleAttempt, THUMB_EDGE, UPLOAD_THUMB_MAX_BYTES, exiftool_binary,
-        fit_upload_thumb, is_video_name, ratio_of, scale_thumbnail, scale_thumbnail_with_exiftool,
-        similar_hashes, thumbnail_build_may_start, upload_thumbnails_with, video_thumbnail,
+        RawTempFile, ScaleAttempt, THUMB_EDGE, UPLOAD_IMAGE_MAX_BYTES, UPLOAD_THUMB_MAX_BYTES,
+        can_make_thumbnail, exiftool_binary, ffmpeg_available, fit_upload_thumb, is_video_name,
+        ratio_of, scale_thumbnail, scale_thumbnail_with_exiftool, similar_hashes,
+        thumbnail_build_may_start, upload_thumbnails_with, video_thumbnail,
     };
     use pdfs_core::control::{ThumbnailBuildStatus, is_thumbnail_image_name};
     use proton_drive_rs::ThumbnailType;
@@ -2149,6 +2177,64 @@ mod thumb_tests {
         assert_eq!(ratio_of(&thumb.bytes).map(|r| r < 1.0), Some(true));
     }
 
+    /// `jpeg` with an EXIF APP1 segment that carries only `orientation`.
+    fn jpeg_with_orientation(width: u32, height: u32, orientation: u16) -> Vec<u8> {
+        let plain = jpeg(width, height);
+        let mut tiff = Vec::new();
+        tiff.extend_from_slice(b"II*\0");
+        tiff.extend_from_slice(&8u32.to_le_bytes());
+        tiff.extend_from_slice(&1u16.to_le_bytes());
+        tiff.extend_from_slice(&0x0112u16.to_le_bytes());
+        tiff.extend_from_slice(&3u16.to_le_bytes());
+        tiff.extend_from_slice(&1u32.to_le_bytes());
+        tiff.extend_from_slice(&orientation.to_le_bytes());
+        tiff.extend_from_slice(&[0, 0]);
+        tiff.extend_from_slice(&0u32.to_le_bytes());
+        let mut app1 = b"Exif\0\0".to_vec();
+        app1.extend_from_slice(&tiff);
+        let mut out = plain[..2].to_vec();
+        out.extend_from_slice(&[0xFF, 0xE1]);
+        out.extend_from_slice(&u16::try_from(app1.len() + 2).unwrap().to_be_bytes());
+        out.extend_from_slice(&app1);
+        out.extend_from_slice(&plain[2..]);
+        out
+    }
+
+    /// A phone stores a portrait photo as landscape pixels and an EXIF
+    /// orientation; its thumbnail came out on its side (`docs/BUGS.md` B226).
+    /// A Takeout photo is copied out of its archive only when a thumbnail can
+    /// be made from the copy.
+    #[test]
+    fn only_a_photo_that_can_have_a_thumbnail_is_worth_copying_out() {
+        assert!(can_make_thumbnail("IMG_1.jpg", 4 << 20));
+        assert!(can_make_thumbnail("Screenshot.png", 4 << 20));
+        assert!(!can_make_thumbnail("IMG_1.jpg", UPLOAD_IMAGE_MAX_BYTES + 1));
+        assert!(!can_make_thumbnail("notes.txt", 10));
+        assert_eq!(can_make_thumbnail("clip.mp4", 1 << 30), ffmpeg_available());
+    }
+
+    #[test]
+    fn a_thumbnail_is_turned_the_way_its_exif_says() {
+        let ScaleAttempt::Made(thumb) = scale_thumbnail(
+            &jpeg_with_orientation(2000, 1000, 6),
+            "portrait.jpg",
+            &std::env::temp_dir(),
+        ) else {
+            panic!("a JPEG scales");
+        };
+        assert!(thumb.ratio < 1.0, "turned upright: {}", thumb.ratio);
+        assert_eq!(ratio_of(&thumb.bytes).map(|r| r < 1.0), Some(true));
+
+        let ScaleAttempt::Made(level) = scale_thumbnail(
+            &jpeg_with_orientation(2000, 1000, 1),
+            "landscape.jpg",
+            &std::env::temp_dir(),
+        ) else {
+            panic!("a JPEG scales");
+        };
+        assert!(level.ratio > 1.0);
+    }
+
     #[test]
     fn undecodable_bytes_are_not_a_thumbnail() {
         // What a photo in a format this build has no decoder for looks like: the

crates/pdfs-fuse/src/profile.rs

@@ -15,6 +15,7 @@ use pdfs_core::control::RestorableFolder;
 use pdfs_core::mounts::MountMode;
 use pdfs_core::profile::{
     PROFILE_DIR_NAME, PROFILE_FILE_NAME, PROFILE_VERSION, Profile, ProfileFolder, ProfilePin,
+    is_profile_file_name, profile_file_name, saved_folder,
 };
 use pdfs_core::{CoreError, CoreResult};
 use proton_drive_rs::proton_sdk::ids::NodeUid;
@@ -66,9 +67,14 @@ impl Core {
         });
     }
 
-    /// Serialize this machine's arrangement and upload it to `profile.json`
-    /// inside the device's `.proton-drive-linux` folder, replacing any existing
-    /// one.
+    /// Serialize this machine's arrangement and upload it to its own
+    /// `profile-<machine id>.json` inside the device's `.proton-drive-linux`
+    /// folder, replacing any existing one.
+    ///
+    /// Each machine writes its own file because several computers may sync
+    /// into one device. They used to share `profile.json`, and each save
+    /// replaced the other computers' folders with its own (B252). That file is
+    /// left as it is, so a client before 3.5.0 still finds it.
     ///
     /// Does nothing when no device is registered: a machine that has never
     /// synced a folder has nothing to describe, and registering a device just to
@@ -85,7 +91,11 @@ impl Core {
             CoreError::internal(format!("bad device root uid: {}", device.root_uid))
         })?;
 
-        let profile = self.build_profile(&device.uid)?;
+        let machine_id = pdfs_core::config::AppDirs::new()
+            .and_then(|dirs| dirs.machine_id())
+            .map_err(|e| CoreError::internal(format!("machine id: {e}")))?;
+        let file_name = profile_file_name(&machine_id);
+        let profile = self.build_profile(&device.uid, &machine_id)?;
         let bytes = profile.to_bytes().map_err(CoreError::internal)?;
         let len = bytes.len() as i64;
 
@@ -97,7 +107,7 @@ impl Core {
         // same name: the profile is a single mutable record, and a folder with
         // `profile.json` and `profile (1).json` in it teaches the restore
         // nothing about which to trust.
-        let existing = self.find_device_child_file(&dir_uid, PROFILE_FILE_NAME)?;
+        let existing = self.find_device_child_file(&dir_uid, &file_name)?;
         match existing {
             Some(uid) => self
                 .rt
@@ -114,7 +124,7 @@ impl Core {
                 self.rt
                     .block_on(self.drive.upload_file_replacing_draft_from(
                         &dir_uid,
-                        PROFILE_FILE_NAME,
+                        &file_name,
                         "application/json",
                         Cursor::new(bytes),
                         len,
@@ -130,7 +140,7 @@ impl Core {
     }
 
     /// Snapshot the local arrangement into a [`Profile`].
-    fn build_profile(&self, device_uid: &str) -> CoreResult<Profile> {
+    fn build_profile(&self, device_uid: &str, machine_id: &str) -> CoreResult<Profile> {
         let folders = self
             .db
             .sync_folder_list()
@@ -162,6 +172,7 @@ impl Core {
             version: PROFILE_VERSION,
             device_uid: device_uid.to_string(),
             hostname: this_hostname(),
+            machine_id: Some(machine_id.to_string()),
             saved_at: now_secs(),
             folders,
             pins,
@@ -197,6 +208,31 @@ impl Core {
             .map(|n| n.uid))
     }
 
+    /// The untrashed files directly under `parent_uid` whose name passes
+    /// `keep`.
+    fn device_child_files(
+        &self,
+        parent_uid: &NodeUid,
+        keep: impl Fn(&str) -> bool,
+    ) -> CoreResult<Vec<NodeUid>> {
+        let uids = self
+            .rt
+            .block_on(self.drive.enumerate_folder_children_node_uids(parent_uid))
+            .map_err(|e| CoreError::from_api(&e, "list device root"))?;
+        if uids.is_empty() {
+            return Ok(Vec::new());
+        }
+        let nodes = self
+            .rt
+            .block_on(self.drive.enumerate_nodes(&uids))
+            .map_err(|e| CoreError::from_api(&e, "resolve device root children"))?;
+        Ok(nodes
+            .into_iter()
+            .filter(|n| !n.is_folder() && !n.trashed && keep(&n.name))
+            .map(|n| n.uid)
+            .collect())
+    }
+
     /// The device's `.proton-drive-linux` folder, creating it if this is the
     /// first save on this device.
     ///
@@ -218,32 +254,43 @@ impl Core {
         Ok(uid)
     }
 
-    /// Download and parse this device's profile, if there is one.
+    /// Download and parse the profiles of every computer that syncs this
+    /// device.
     ///
-    /// Looks in `.proton-drive-linux/` first and falls back to the device root,
-    /// where clients before the B78 fix wrote it. The fallback is read-only: the
-    /// next save writes to the folder, and the legacy document is left alone
-    /// rather than trashed, so an older client on another machine keeps working.
-    fn load_profile(&self, root_uid: &NodeUid) -> CoreResult<Option<Profile>> {
-        let current = match self.find_device_child_folder(root_uid, PROFILE_DIR_NAME)? {
-            Some(dir_uid) => self.find_device_child_file(&dir_uid, PROFILE_FILE_NAME)?,
-            None => None,
+    /// Reads every profile in `.proton-drive-linux/`: one per machine, and the
+    /// shared `profile.json` of clients before 3.5.0. Falls back to the device
+    /// root, where clients before the B78 fix wrote it. The fallback is
+    /// read-only: the next save writes to the folder, and the legacy document
+    /// is left alone rather than trashed, so an older client on another
+    /// machine keeps working. A profile that cannot be read is left out and
+    /// logged; the others still count.
+    fn load_profiles(&self, root_uid: &NodeUid) -> CoreResult<Vec<Profile>> {
+        let mut uids = match self.find_device_child_folder(root_uid, PROFILE_DIR_NAME)? {
+            Some(dir_uid) => self.device_child_files(&dir_uid, is_profile_file_name)?,
+            None => Vec::new(),
         };
-        let uid = match current {
-            Some(uid) => uid,
-            None => match self.find_device_child_file(root_uid, PROFILE_FILE_NAME)? {
-                Some(uid) => {
-                    info!("reading legacy profile from the device root");
-                    uid
+        if uids.is_empty() {
+            uids = self.device_child_files(root_uid, |name| name == PROFILE_FILE_NAME)?;
+            if !uids.is_empty() {
+                info!("reading legacy profile from the device root");
+            }
+        }
+        let mut profiles = Vec::new();
+        for uid in uids {
+            let mut buf: Vec<u8> = Vec::new();
+            let parsed = self
+                .rt
+                .block_on(self.drive.download_file_to(&uid, &mut buf))
+                .map_err(|e| CoreError::from_api(&e, "download profile"))
+                .and_then(|()| Profile::parse(&buf).map_err(CoreError::invalid));
+            match parsed {
+                Ok(profile) => profiles.push(profile),
+                Err(e) => {
+                    warn!(%uid, error = %e.message, "could not read a profile; leaving it out")
                 }
-                None => return Ok(None),
-            },
-        };
-        let mut buf: Vec<u8> = Vec::new();
-        self.rt
-            .block_on(self.drive.download_file_to(&uid, &mut buf))
-            .map_err(|e| CoreError::from_api(&e, "download profile"))?;
-        Profile::parse(&buf).map(Some).map_err(CoreError::invalid)
+            }
+        }
+        Ok(profiles)
     }
 
     // ---- restore ----------------------------------------
@@ -265,15 +312,16 @@ impl Core {
             CoreError::internal(format!("bad device root uid: {}", device.root_uid))
         })?;
 
-        let profile = match self.load_profile(&root_uid) {
+        let profiles = match self.load_profiles(&root_uid) {
             Ok(p) => p,
             // A missing or unreadable profile is not fatal: the remote tree
             // alone is enough to offer a restore, just with plainer defaults.
             Err(e) => {
-                warn!(error = %e.message, "could not read profile; proposing defaults");
-                None
+                warn!(error = %e.message, "could not read profiles; proposing defaults");
+                Vec::new()
             }
         };
+        let hostname = this_hostname();
 
         let uids = self
             .rt
@@ -304,11 +352,12 @@ impl Core {
             // offering it as a restorable folder would sync the bookkeeping
             // back onto the machine it describes.
             .filter(|n| n.is_folder() && !n.trashed && n.name != PROFILE_DIR_NAME)
+            // The name becomes a folder under the home folder: one with a `/`
+            // or a `..` in it would put the restore somewhere else.
+            .filter(|n| crate::remote_name_is_safe(&n.name))
             .map(|n| {
                 let uid = n.uid.to_string();
-                let saved = profile
-                    .as_ref()
-                    .and_then(|p| p.folders.iter().find(|f| f.remote_uid == uid));
+                let saved = saved_folder(&profiles, &uid, &hostname);
                 let proposed = saved
                     .map(|f| PathBuf::from(&f.local_path))
                     .filter(|p| path_is_usable_here(p))
@@ -339,7 +388,7 @@ impl Core {
         &self,
         items: &[pdfs_core::control::RestoreItem],
         device: Option<&str>,
-    ) -> CoreResult<String> {
+    ) -> CoreResult<RestoreOutcome> {
         if items.is_empty() {
             return Err(CoreError::invalid("nothing to restore"));
         }
@@ -349,23 +398,29 @@ impl Core {
             .sync_folder_list()
             .map_err(|e| CoreError::internal(format!("db: {e:?}")))?;
 
+        let reserved = crate::devices::sync_root_reserved();
+        let mut roots: Vec<PathBuf> = existing
+            .iter()
+            .map(|f| PathBuf::from(&f.local_path))
+            .collect();
         let mut restored = 0usize;
         let mut skipped: Vec<String> = Vec::new();
         for item in items {
-            let local = PathBuf::from(&item.local_path);
-            if !local.is_absolute() {
-                skipped.push(format!("{}: local path must be absolute", item.local_path));
-                continue;
-            }
+            // The path is proposed from the profile another machine wrote, and
+            // may hold a folder name from Drive: checked like any new root.
+            let local = match pdfs_core::syncroot::resolve(Path::new(&item.local_path)) {
+                Ok(local) => local,
+                Err(e) => {
+                    skipped.push(format!("{}: {e}", item.local_path));
+                    continue;
+                }
+            };
             if existing.iter().any(|f| f.remote_uid == item.remote_uid) {
                 skipped.push(format!("{}: already synced", item.local_path));
                 continue;
             }
-            if existing
-                .iter()
-                .any(|f| Path::new(&f.local_path) == local.as_path())
-            {
-                skipped.push(format!("{}: path already in use", item.local_path));
+            if let Some(problem) = pdfs_core::syncroot::problem(&local, &roots, &reserved) {
+                skipped.push(format!("{}: {problem}", item.local_path));
                 continue;
             }
             if let Err(e) = std::fs::create_dir_all(&local) {
@@ -379,10 +434,19 @@ impl Core {
                     continue;
                 }
             };
-            let id = self
-                .db
-                .sync_folder_add(&local.to_string_lossy(), &item.remote_uid, &device.share_id)
-                .map_err(|e| CoreError::internal(format!("db: {e:?}")))?;
+            let id = match self.db.sync_folder_add(
+                &local.to_string_lossy(),
+                &item.remote_uid,
+                &device.share_id,
+            ) {
+                Ok(id) => id,
+                Err(e) => {
+                    // The folders restored before this one still need their
+                    // watches.
+                    let _ = self.sync_tx.send(sync::SyncMsg::Rewatch);
+                    return Err(CoreError::internal(format!("db: {e:?}")));
+                }
+            };
             // `ondemand` is applied through the normal request path, which
             // mounts the FUSE session and handles the folder being busy — the
             // restore does not get its own copy of that logic.
@@ -390,16 +454,44 @@ impl Core {
                 let _ = self.request_sync_folder_mode(id, "ondemand");
             }
             let _ = self.sync_tx.send(sync::SyncMsg::Reconcile(id));
+            roots.push(local);
             restored += 1;
         }
         let _ = self.sync_tx.send(sync::SyncMsg::Rewatch);
 
-        let mut message = format!("restored {restored} folder(s)");
-        if !skipped.is_empty() {
-            message.push_str(&format!("; skipped: {}", skipped.join(", ")));
+        // The reply is gone once the app has shown it; the log keeps why.
+        for reason in &skipped {
+            info!(reason, "restore skipped a folder");
         }
         info!(restored, skipped = skipped.len(), "restore complete");
-        Ok(message)
+        Ok(RestoreOutcome { restored, skipped })
+    }
+}
+
+/// What a restore did: how many folders it attached, and why it left out the
+/// others.
+pub(crate) struct RestoreOutcome {
+    pub(crate) restored: usize,
+    pub(crate) skipped: Vec<String>,
+}
+
+impl RestoreOutcome {
+    /// The activity entry's headline.
+    pub(crate) fn summary(&self) -> String {
+        match (self.restored, self.skipped.len()) {
+            (n, 0) => format!("restored {n} folder(s)"),
+            (0, k) => format!("restored no folders; skipped {k}"),
+            (n, k) => format!("restored {n} folder(s); skipped {k}"),
+        }
+    }
+
+    /// Whether the restore did all it was asked. A skipped folder is a
+    /// failure the user has to see: the reply went out as "restoring folders"
+    /// before any work, and a restore that skipped every folder used to be
+    /// logged as a success, so nothing anywhere said that nothing would
+    /// download (`docs/BUGS.md` B269).
+    pub(crate) fn complete(&self) -> bool {
+        self.skipped.is_empty()
     }
 }
 
@@ -482,7 +574,7 @@ mod tests {
     #[test]
     fn loading_falls_back_to_a_legacy_device_root_profile() {
         let source = include_str!("profile.rs");
-        let load = function_source(source, "fn load_profile(");
+        let load = function_source(source, "fn load_profiles(");
         assert!(load.contains("PROFILE_DIR_NAME"), "prefers the folder");
         assert!(
             load.find("PROFILE_DIR_NAME").unwrap()
@@ -491,6 +583,16 @@ mod tests {
         );
     }
 
+    /// Several computers may share a device, so each saves to a file named
+    /// after its own machine id and never to the shared `profile.json`
+    /// (B252).
+    #[test]
+    fn each_machine_saves_its_own_profile() {
+        let save = function_source(include_str!("profile.rs"), "fn save_profile(");
+        assert!(save.contains("profile_file_name(&machine_id)"));
+        assert!(!save.contains("PROFILE_FILE_NAME"));
+    }
+
     /// The profile folder is the client's own bookkeeping: neither the restore
     /// picker nor `add_sync_folder` may treat it as a user folder.
     #[test]

crates/pdfs-fuse/src/reads.rs

@@ -1070,37 +1070,121 @@ impl Core {
         offset: u64,
         size: u64,
     ) -> Result<Vec<u8>, Errno> {
-        if offset >= len || size == 0 {
-            return Ok(Vec::new());
+        let read = assemble_open_read(file, len, uid, base_size, written, offset, size, |s, n| {
+            self.read_range(uid, base_mtime, base_size, s, n, true)
+                .map(Some)
+        })?;
+        Ok(read.unwrap_or_default())
+    }
+
+    /// [`Core::serve_open_read`] from bytes already on this machine only:
+    /// `Ok(None)` the moment a range of the base would have to be downloaded.
+    ///
+    /// The dispatch loop answers a read on a write handle with this, and hands
+    /// it to a worker only when it says `None`. Fetching the base there held
+    /// every request of the mount for as long as the download took, up to the
+    /// read deadline (`docs/BUGS.md` B227).
+    #[allow(clippy::too_many_arguments)]
+    pub(super) fn serve_open_read_local(
+        &self,
+        file: &Arc<File>,
+        len: u64,
+        uid: &NodeUid,
+        base_mtime: i64,
+        base_size: u64,
+        written: &Intervals,
+        offset: u64,
+        size: u64,
+    ) -> Result<Option<Vec<u8>>, Errno> {
+        assemble_open_read(file, len, uid, base_size, written, offset, size, |s, n| {
+            Ok(self.cached_range(uid, base_mtime, base_size, s, n))
+        })
+    }
+
+    /// Bytes `[offset, offset + size)` of file `ino` as `read` would serve
+    /// them, but only from this machine: an open write handle, a queued write,
+    /// or the caches. `Ok(None)` the moment any of it would have to be
+    /// downloaded, and for a size still provisional (B100), which only the
+    /// network settles. Short or empty past the end of the file.
+    ///
+    /// `copy_file_range` answers with this and leaves anything else to the
+    /// kernel's read/write copy.
+    pub(super) fn read_local(
+        &self,
+        ino: u64,
+        offset: u64,
+        size: u64,
+    ) -> Result<Option<Vec<u8>>, Errno> {
+        let handle = self.state().active_writes.get(&ino).map(|h| {
+            (
+                h.file.clone(),
+                h.len,
+                h.uid.clone(),
+                h.base_mtime,
+                h.base_size,
+                h.written.clone(),
+            )
+        });
+        if let Some((file, len, uid, base_mtime, base_size, written)) = handle {
+            return self.serve_open_read_local(
+                &file, len, &uid, base_mtime, base_size, &written, offset, size,
+            );
         }
-        let end = offset.saturating_add(size).min(len);
-        let mut out = Vec::with_capacity((end - offset) as usize);
-        for (s, e, authored) in written.segments(offset, end) {
-            if authored {
-                let mut buf = vec![0u8; (e - s) as usize];
-                file.read_exact_at(&mut buf, s).map_err(|err| {
-                    warn!(%uid, error = %err, "scratch read failed");
-                    Errno::EIO
-                })?;
-                out.extend_from_slice(&buf);
-            } else {
-                let bend = e.min(base_size);
-                if s < bend {
-                    out.extend_from_slice(&self.read_range(
-                        uid,
-                        base_mtime,
-                        base_size,
-                        s,
-                        bend - s,
-                        true,
-                    )?);
-                }
-                // Anything past the base is a hole: zero-fill.
-                let zeros = e.saturating_sub(s.max(base_size));
-                out.resize(out.len() + zeros as usize, 0);
+        let (uid, mtime, fsize, provisional) = {
+            let st = self.state();
+            match st.entries.get(&ino) {
+                Some(e) if e.node.is_file() => (
+                    e.uid.clone(),
+                    e.node.modification_time,
+                    node_size(&e.node),
+                    matches!(
+                        &e.node.kind,
+                        NodeKind::File {
+                            claimed_size: None,
+                            ..
+                        }
+                    ),
+                ),
+                Some(_) => return Err(Errno::EISDIR),
+                None => return Err(Errno::ENOENT),
             }
+        };
+        let uid = match is_local_uid(&uid) {
+            true => self.landed_stand_in_uid(&uid).unwrap_or(uid),
+            false => uid,
+        };
+        if let Some(pending) = self.pending.lock().get(&uid).cloned() {
+            let m = &pending.meta;
+            let file = File::open(&pending.path).map_err(|e| {
+                error!(%uid, path = %pending.path.display(), error = %e, "open staged blob failed");
+                Errno::EIO
+            })?;
+            let mut written = Intervals::default();
+            for &(s, e) in &m.authored {
+                written.add(s, e);
+            }
+            return self.serve_open_read_local(
+                &Arc::new(file),
+                m.len,
+                &uid,
+                m.base_mtime,
+                m.base_size,
+                &written,
+                offset,
+                size,
+            );
         }
-        Ok(out)
+        // Created here and never written: an empty file.
+        if is_local_uid(&uid) {
+            return Ok(Some(Vec::new()));
+        }
+        if provisional {
+            return Ok(None);
+        }
+        if offset >= fsize || size == 0 {
+            return Ok(Some(Vec::new()));
+        }
+        Ok(self.cached_range(&uid, mtime, fsize, offset, size.min(fsize - offset)))
     }
 
     /// The largest amount [`Core::fill_gaps_cached`] will copy out of the local
@@ -1242,6 +1326,49 @@ impl Core {
     }
 }
 
+/// The bytes `[offset, offset + size)` of a file open for writing: authored
+/// ranges from its scratch `file`, the rest from its base through `base`,
+/// and zeros past the base. `Ok(None)` when `base` says it cannot answer.
+#[allow(clippy::too_many_arguments)]
+fn assemble_open_read(
+    file: &File,
+    len: u64,
+    uid: &NodeUid,
+    base_size: u64,
+    written: &Intervals,
+    offset: u64,
+    size: u64,
+    mut base: impl FnMut(u64, u64) -> Result<Option<Vec<u8>>, Errno>,
+) -> Result<Option<Vec<u8>>, Errno> {
+    if offset >= len || size == 0 {
+        return Ok(Some(Vec::new()));
+    }
+    let end = offset.saturating_add(size).min(len);
+    let mut out = Vec::with_capacity((end - offset) as usize);
+    for (s, e, authored) in written.segments(offset, end) {
+        if authored {
+            let mut buf = vec![0u8; (e - s) as usize];
+            file.read_exact_at(&mut buf, s).map_err(|err| {
+                warn!(%uid, error = %err, "scratch read failed");
+                Errno::EIO
+            })?;
+            out.extend_from_slice(&buf);
+        } else {
+            let bend = e.min(base_size);
+            if s < bend {
+                match base(s, bend - s)? {
+                    Some(bytes) => out.extend_from_slice(&bytes),
+                    None => return Ok(None),
+                }
+            }
+            // Anything past the base is a hole: zero-fill.
+            let zeros = e.saturating_sub(s.max(base_size));
+            out.resize(out.len() + zeros as usize, 0);
+        }
+    }
+    Ok(Some(out))
+}
+
 #[cfg(test)]
 mod block_ring_tests {
     use super::*;
@@ -1394,3 +1521,54 @@ mod prefetch_tests {
         assert!(prefetch.streams.lock().len() <= MAX_PREFETCH_STREAMS + 1);
     }
 }
+
+#[cfg(test)]
+mod open_read_tests {
+    use super::*;
+    use proton_drive_rs::proton_sdk::ids::{LinkId, VolumeId};
+
+    fn scratch(bytes: &[u8]) -> (File, PathBuf) {
+        let path = std::env::temp_dir().join(format!(
+            "pdfs-open-read-{}-{}",
+            std::process::id(),
+            std::time::SystemTime::now()
+                .duration_since(std::time::UNIX_EPOCH)
+                .unwrap()
+                .as_nanos()
+        ));
+        let mut file = File::options()
+            .create_new(true)
+            .read(true)
+            .write(true)
+            .open(&path)
+            .unwrap();
+        file.write_all(bytes).unwrap();
+        (file, path)
+    }
+
+    /// The dispatch loop answers from what is on this machine and says so
+    /// when the base would have to be downloaded, for a worker to do it
+    /// (`docs/BUGS.md` B227).
+    #[test]
+    fn a_read_needing_the_base_says_so_instead_of_fetching() {
+        let uid = NodeUid::new(VolumeId::from("v"), LinkId::from("f"));
+        let (file, path) = scratch(b"ABCDEFGH");
+        let mut written = Intervals::default();
+        written.add(0, 4);
+
+        let authored = assemble_open_read(&file, 8, &uid, 8, &written, 0, 4, |_, _| {
+            panic!("an authored range never asks the base")
+        });
+        assert_eq!(authored.unwrap().as_deref(), Some(&b"ABCD"[..]));
+
+        let missing = assemble_open_read(&file, 8, &uid, 8, &written, 2, 6, |_, _| Ok(None));
+        assert_eq!(missing.unwrap(), None);
+
+        let base = assemble_open_read(&file, 10, &uid, 8, &written, 2, 8, |s, n| {
+            assert_eq!((s, n), (4, 4));
+            Ok(Some(b"efgh".to_vec()))
+        });
+        assert_eq!(base.unwrap().as_deref(), Some(&b"CDefgh\0\0"[..]));
+        let _ = std::fs::remove_file(path);
+    }
+}

crates/pdfs-fuse/src/redate.rs

@@ -190,6 +190,7 @@ impl Core {
             .map_err(|e| CoreError::internal(format!("stat {}: {e}", path.display())))?
             .len();
         let media_type = media_type_of(&candidate.name).unwrap_or("application/octet-stream");
+        let thumbnails = self.upload_thumbnails(&path, &candidate.name);
 
         let guard =
             self.transfers
@@ -206,7 +207,7 @@ impl Core {
             media_type,
             reader,
             size as i64,
-            Vec::new(),
+            thumbnails,
             metadata,
             false,
         ));
@@ -291,7 +292,14 @@ impl Core {
             let mut state = REDATE.lock();
             state.running = false;
             state.cancel = None;
-            state.last = outcome.as_ref().ok().cloned();
+            state.last = Some(match &outcome {
+                Ok(summary) => summary.clone(),
+                Err(e) => RedateSummary {
+                    error: Some(e.to_string()),
+                    dry_run,
+                    ..Default::default()
+                },
+            });
             match &outcome {
                 Ok(summary) => info!(
                     candidates = summary.candidates,

crates/pdfs-fuse/src/relocate.rs

@@ -25,6 +25,7 @@ use proton_drive_rs::NodeKind;
 use proton_drive_rs::proton_sdk::ids::NodeUid;
 use tracing::{info, warn};
 
+use super::state::State;
 use super::sync::mirror_subtree_unsynced;
 use super::{Core, is_local_uid, parse_uid};
 
@@ -130,6 +131,24 @@ fn rename_noreplace(from: &Path, to: &Path) -> std::io::Result<()> {
     }
 }
 
+/// Whether inode `ino` is `root` or lies under it in the tree. Bounded, so a
+/// parent cycle in corrupt data cannot hang the caller.
+pub(crate) fn ino_is_under(st: &State, mut ino: u64, root: u64) -> bool {
+    for _ in 0..MAX_TREE_DEPTH {
+        if ino == root {
+            return true;
+        }
+        match st.entries.get(&ino) {
+            Some(entry) if entry.parent != ino => ino = entry.parent,
+            _ => return false,
+        }
+    }
+    false
+}
+
+/// How deep [`ino_is_under`] walks before it gives up.
+const MAX_TREE_DEPTH: usize = 1024;
+
 /// Whether `uid` is `root` or lies under it, as far as the nodes table knows.
 fn under(core: &Core, root: &NodeUid, uid: &str) -> bool {
     let root = root.to_string();
@@ -336,7 +355,7 @@ impl Core {
                     core.require_uid_writable(authority)
                         .map_err(|e| core.errno_error(e, "move access"))?;
                 }
-                if self.has_pending_work_under(&uid)? {
+                if self.has_pending_work_under(ino, &uid)? {
                     return Err(CoreError::conflict(
                         "it has changes that are not uploaded yet; wait for the upload to finish",
                     ));
@@ -410,10 +429,11 @@ impl Core {
         Ok(uid)
     }
 
-    /// Whether the queue owes Drive anything for `uid` or a node under it, or a
-    /// file under it is open for writing. Moving such a node away would strand
-    /// the pending change against a path that no longer leads to it.
-    fn has_pending_work_under(&self, uid: &NodeUid) -> CoreResult<bool> {
+    /// Whether the queue owes Drive anything for `uid` (inode `ino`) or a node
+    /// under it, or a file under it is open for writing. Moving such a node away
+    /// would strand the pending change against a path that no longer leads to
+    /// it.
+    fn has_pending_work_under(&self, ino: u64, uid: &NodeUid) -> CoreResult<bool> {
         let ops = self
             .db
             .pending_ops()
@@ -427,12 +447,19 @@ impl Core {
         }) {
             return Ok(true);
         }
-        // Collected first so no State lock is held across the nodes-table reads.
-        let mut writing = Vec::new();
+        // Open handles are placed in the tree by inode, not by uid in the nodes
+        // table. A file opened just after its create landed holds the
+        // placeholder uid until the tree catches up, and the nodes table no
+        // longer has that uid, so the move went ahead under an open write.
+        let mut writing = false;
         self.for_each_state(|st| {
-            writing.extend(st.active_writes.values().map(|w| w.uid.to_string()));
+            writing = st
+                .active_writes
+                .keys()
+                .chain(&st.releasing)
+                .any(|&open| ino_is_under(st, open, ino));
         });
-        Ok(writing.iter().any(|w| under(self, uid, w)))
+        Ok(writing)
     }
 
     /// Bring the source location level with a move Drive has made.

crates/pdfs-fuse/src/sharing.rs

@@ -9,7 +9,8 @@
 use std::path::Path;
 
 use pdfs_core::control::{
-    BookmarkInfo, DirEntry, InvitationInfo, PublicLinkInfo, ShareEntry, ShareEntryKind, SharedItem,
+    BookmarkInfo, DirEntry, InvitationInfo, LinkChange, PublicLinkInfo, ShareEntry, ShareEntryKind,
+    SharedItem,
 };
 use pdfs_core::{CoreError, CoreResult};
 use tracing::debug;
@@ -66,6 +67,7 @@ fn shared_entry_of(core: &Core, n: Node) -> DirEntry {
         size,
         modified: n.modification_time,
         pinned: false,
+        pinned_by_folder: false,
         cached: false,
         path: core.rel_path_for_uid(&n.uid).unwrap_or_default(),
         uid: n.uid.to_string(),
@@ -366,6 +368,89 @@ impl Core {
         Ok(public_link_info(link))
     }
 
+    /// Change the public link `id` on the node at `rel`, keeping its URL.
+    pub(crate) fn update_public_link(
+        &self,
+        rel: &Path,
+        id: &str,
+        role: Option<&str>,
+        password: LinkChange<String>,
+        expires: LinkChange<i64>,
+    ) -> CoreResult<PublicLinkInfo> {
+        let (_ino, uid) = self.resolve(rel)?;
+        self.update_public_link_for_uid(&uid, id, role, password, expires)
+    }
+
+    /// [`Core::update_public_link`] for a node addressed through any daemon
+    /// location.
+    pub(crate) fn update_public_link_by_uid(
+        &self,
+        uid: &str,
+        id: &str,
+        role: Option<&str>,
+        password: LinkChange<String>,
+        expires: LinkChange<i64>,
+    ) -> CoreResult<PublicLinkInfo> {
+        let uid = self.resolve_anywhere(uid)?;
+        self.update_public_link_for_uid(&uid, id, role, password, expires)
+    }
+
+    /// The SDK sets all three options on every update, so each `Keep` is
+    /// filled in from the link as it stands.
+    fn update_public_link_for_uid(
+        &self,
+        uid: &NodeUid,
+        id: &str,
+        role: Option<&str>,
+        password: LinkChange<String>,
+        expires: LinkChange<i64>,
+    ) -> CoreResult<PublicLinkInfo> {
+        let link = self
+            .rt
+            .block_on(self.client.get_public_link(uid))
+            .map_err(|e| CoreError::from_api(&e, "get public link"))?
+            .filter(|l| l.public_link_id == id)
+            .ok_or_else(|| CoreError::not_found("public link not found"))?;
+        let role = match role {
+            Some(role) => role_from_str(role)?,
+            None => link.role,
+        };
+        let unchanged = role == link.role
+            && matches!(password, LinkChange::Keep)
+            && matches!(expires, LinkChange::Keep);
+        if unchanged {
+            return Ok(public_link_info(link));
+        }
+        let password = match password {
+            LinkChange::Keep if link.has_custom_password => {
+                // Sending `None` here would quietly remove the password.
+                Some(link.custom_password.clone().ok_or_else(|| {
+                    CoreError::conflict(
+                        "the link's password could not be read; set a new one or remove it",
+                    )
+                })?)
+            }
+            LinkChange::Keep | LinkChange::Remove => None,
+            LinkChange::Set(password) if password.is_empty() => {
+                return Err(CoreError::invalid("the new password is empty"));
+            }
+            LinkChange::Set(password) => Some(password),
+        };
+        let expires = match expires {
+            LinkChange::Keep => link.expiration_time,
+            LinkChange::Remove => None,
+            LinkChange::Set(at) => Some(at),
+        };
+        let link = self
+            .rt
+            .block_on(
+                self.client
+                    .update_public_link(uid, role, password.as_deref(), expires),
+            )
+            .map_err(|e| CoreError::from_api(&e, "update public link"))?;
+        Ok(public_link_info(link))
+    }
+
     /// Remove the public link `id` from the node at `rel`.
     pub(crate) fn remove_public_link(&self, rel: &Path, id: &str) -> CoreResult<()> {
         let (_ino, uid) = self.resolve(rel)?;
@@ -660,6 +745,12 @@ impl Core {
     /// the shared uids; the per-node detail is then gathered best-effort — a single
     /// node racing with an unshare drops from the list rather than failing the whole
     /// request.
+    ///
+    /// A share with no member, no invitation and no link is left out: it is
+    /// shared with no one. Stop Sharing leaves exactly that behind, since the SDK
+    /// cannot delete a share, and Drive keeps listing it until its backend gets
+    /// round to removing it, minutes later. A share whose details could not all
+    /// be read stays listed, so a failed lookup never hides a live share.
     pub(crate) fn list_shared_by_me(&self) -> CoreResult<Vec<SharedItem>> {
         let uids = self
             .rt
@@ -678,24 +769,26 @@ impl Core {
             let members = self
                 .rt
                 .block_on(self.client.list_share_members(&uid))
-                .map(|m| m.len())
-                .unwrap_or(0);
+                .map(|m| m.len());
             let proton_invites = self
                 .rt
                 .block_on(self.client.list_share_invitations(&uid))
-                .map(|i| i.len())
-                .unwrap_or(0);
+                .map(|i| i.len());
             let external_invites = self
                 .rt
                 .block_on(self.client.list_external_invitations(&uid))
-                .map(|i| i.len())
-                .unwrap_or(0);
-            let link = self
-                .rt
-                .block_on(self.client.get_public_link(&uid))
-                .ok()
-                .flatten()
-                .map(public_link_info);
+                .map(|i| i.len());
+            let link = self.rt.block_on(self.client.get_public_link(&uid));
+            if let (Ok(0), Ok(0), Ok(0), Ok(None)) =
+                (&members, &proton_invites, &external_invites, &link)
+            {
+                debug!(%uid, "shared by me: skipping an emptied share");
+                continue;
+            }
+            let members = members.unwrap_or(0);
+            let proton_invites = proton_invites.unwrap_or(0);
+            let external_invites = external_invites.unwrap_or(0);
+            let link = link.ok().flatten().map(public_link_info);
             items.push(SharedItem {
                 uid: uid.to_string(),
                 is_dir: n.is_folder(),

crates/pdfs-fuse/src/sim/fake_drive.rs

@@ -31,6 +31,9 @@
 //! - **A full account** ([`FakeDrive::set_quota`]) refusing uploads with
 //!   `InsufficientQuota`.
 //!
+//! It also holds the account's computers, each with a root folder outside My
+//! files, so a simulated daemon can register its own and sync a local folder.
+//!
 //! A test can also hold the next read of one node on its way to Drive
 //! ([`FakeClient::hold_next_read`]), to make a change while the daemon waits
 //! for the answer, or on its way back ([`FakeClient::hold_answer_to_next_read`]),
@@ -54,9 +57,12 @@ use parking_lot::Mutex;
 use proton_drive_rs::proton_sdk::account::Quota;
 use proton_drive_rs::proton_sdk::api::ResponseCode;
 use proton_drive_rs::proton_sdk::error::{ProtonApiError, ProtonError, Result};
-use proton_drive_rs::proton_sdk::ids::{DriveEventId, LinkId, NodeUid, VolumeId};
+use proton_drive_rs::proton_sdk::ids::{
+    DeviceUid, DriveEventId, LinkId, NodeUid, ShareId, VolumeId,
+};
 use proton_drive_rs::{
-    DriveEvent, DriveEventScopeId, Node, NodeKind, NodeMoveItem, RevisionState, Thumbnail,
+    AvailableNameTarget, Device as Computer, DeviceType, DriveEvent, DriveEventScopeId, Node,
+    NodeKind, NodeMoveItem, RevisionState, Thumbnail,
 };
 use sha1::{Digest as _, Sha1};
 
@@ -111,6 +117,9 @@ struct Server {
     block_pattern: Vec<u64>,
     /// The account's storage limit in bytes.
     max_space: i64,
+    /// The account's computers, oldest first, as `(name, type, root folder)`.
+    /// [`Computer`] is not `Clone`, so each answer builds them afresh.
+    devices: Vec<(String, DeviceType, NodeUid)>,
 }
 
 impl Server {
@@ -162,6 +171,53 @@ impl Server {
         false
     }
 
+    /// The `n`th computer of the account, as Drive lists it.
+    fn computer(&self, n: usize) -> Computer {
+        let (name, device_type, root) = &self.devices[n];
+        Computer {
+            uid: DeviceUid::new(format!("device{}", n + 1)),
+            device_type: *device_type,
+            name: Ok(name.clone()),
+            root_folder_uid: root.clone(),
+            creation_time: self.current(root).map_or(0, |remote| remote.created),
+            last_sync_time: None,
+            share_id: ShareId::new(format!("device-share{}", n + 1)),
+        }
+    }
+
+    /// Copy `uid` and, for a folder, everything live below it under `parent` as
+    /// `name`, the way Drive's copy endpoint does. Returns the copy's uid.
+    fn copy_subtree(&mut self, uid: &NodeUid, parent: &NodeUid, name: String) -> NodeUid {
+        let source = self
+            .current(uid)
+            .cloned()
+            .expect("the caller checked the source");
+        let copy = self.mint_uid();
+        let now = now_secs();
+        self.put(
+            &copy,
+            Some(Remote {
+                parent: Some(parent.clone()),
+                name,
+                created: now,
+                ..source
+            }),
+        );
+        let children: Vec<(NodeUid, String)> = self
+            .nodes
+            .keys()
+            .filter_map(|child| {
+                let remote = self.current(child)?;
+                (remote.parent.as_ref() == Some(uid) && !remote.trashed)
+                    .then(|| (child.clone(), remote.name.clone()))
+            })
+            .collect();
+        for (child, child_name) in children {
+            self.copy_subtree(&child, &copy, child_name);
+        }
+        copy
+    }
+
     fn mint_uid(&mut self) -> NodeUid {
         self.next_link += 1;
         uid(&format!("L{}", self.next_link))
@@ -305,6 +361,7 @@ impl FakeDrive {
             events: Vec::new(),
             block_pattern: vec![pdfs_core::cache::BLOCK_SIZE],
             max_space: 1 << 40,
+            devices: Vec::new(),
         };
         let now = now_secs();
         server.nodes.insert(
@@ -338,6 +395,8 @@ impl FakeDrive {
             hold: Mutex::new(None),
             hold_answer: Mutex::new(None),
             hold_trash: Mutex::new(None),
+            hold_download: Mutex::new(None),
+            hold_any_landing: AtomicBool::new(false),
             hold_landing: Mutex::new(None),
             drop_after_create: AtomicBool::new(false),
             lose_create_reply: AtomicBool::new(false),
@@ -616,8 +675,13 @@ struct ClientInner {
     hold_answer: Mutex<Option<Arc<HoldState>>>,
     /// The trash [`FakeClient::hold_next_trash`] is waiting for.
     hold_trash: Mutex<Option<Arc<HoldState>>>,
+    /// The download [`FakeClient::hold_next_download`] is waiting for.
+    hold_download: Mutex<Option<Arc<HoldState>>>,
     /// The landing [`FakeClient::hold_next_landing`] is waiting for.
     hold_landing: Mutex<Option<Arc<HoldState>>>,
+    /// Set by [`FakeClient::hold_next_landing_of_any`]: hold whichever node
+    /// lands next.
+    hold_any_landing: AtomicBool,
     /// Set by [`FakeClient::drop_link_after_next_create`].
     drop_after_create: AtomicBool,
     /// Set by [`FakeClient::lose_reply_to_next_create`].
@@ -755,6 +819,18 @@ impl FakeClient {
         Held(state)
     }
 
+    /// Hold the next download of `uid`'s content once Drive has answered it,
+    /// before the bytes reach the daemon, until the answer is dropped.
+    pub(crate) fn hold_next_download(&self, uid: &NodeUid) -> Held {
+        let state = Arc::new(HoldState {
+            uid: uid.clone(),
+            reached: AtomicBool::new(false),
+            released: AtomicBool::new(false),
+        });
+        *self.0.hold_download.lock() = Some(state.clone());
+        Held(state)
+    }
+
     /// Hold the drain once the next upload to `uid` has landed and its blob
     /// is let go of, before the tree has the node (`DriveApi::landing`), until
     /// the answer is dropped.
@@ -768,6 +844,14 @@ impl FakeClient {
         Held(state)
     }
 
+    /// [`FakeClient::hold_next_landing`] for whichever node lands next, such
+    /// as a new file, whose uid Drive has not minted yet.
+    pub(crate) fn hold_next_landing_of_any(&self) -> Held {
+        let held = self.hold_next_landing(&uid("*"));
+        self.0.hold_any_landing.store(true, Ordering::SeqCst);
+        held
+    }
+
     /// Make the next file create on Drive, then hold its answer until the
     /// answer is dropped, as a slow link does.
     pub(crate) fn hold_reply_to_next_create(&self) -> Held {
@@ -1396,6 +1480,8 @@ impl DriveApi for FakeClient {
                     .ok_or_else(|| api(ResponseCode::DoesNotExist, "file not found"))
             })
             .await?;
+        self.wait_if_held(&self.0.hold_download, std::slice::from_ref(uid))
+            .await;
         output.write_all(&content).map_err(io_error)
     }
 
@@ -1437,6 +1523,61 @@ impl DriveApi for FakeClient {
         .await
     }
 
+    async fn copy_node(
+        &self,
+        uid: &NodeUid,
+        new_parent: &NodeUid,
+        name: Option<&str>,
+    ) -> Result<NodeUid> {
+        self.request(true, |server| {
+            if !server.is_folder(new_parent) {
+                return Err(api(ResponseCode::DoesNotExist, "parent folder not found"));
+            }
+            let source = server
+                .current(uid)
+                .filter(|remote| !remote.trashed)
+                .cloned()
+                .ok_or_else(|| api(ResponseCode::DoesNotExist, "node not found"))?;
+            if server.is_below(new_parent, uid) {
+                return Err(api(
+                    ResponseCode::InvalidRequirements,
+                    "cannot copy a folder into itself",
+                ));
+            }
+            let name = name.map_or(source.name.clone(), str::to_owned);
+            if server.live_child_named(new_parent, &name).is_some() {
+                return Err(api(
+                    ResponseCode::AlreadyExists,
+                    "a file or folder with that name already exists",
+                ));
+            }
+            Ok(server.copy_subtree(uid, new_parent, name))
+        })
+        .await
+    }
+
+    async fn get_available_name(
+        &self,
+        parent_uid: &NodeUid,
+        name: &str,
+        target: AvailableNameTarget,
+    ) -> Result<String> {
+        self.request(false, |server| {
+            let (stem, extension) = match (target, name.rsplit_once('.')) {
+                (AvailableNameTarget::File, Some((stem, ext))) if !stem.is_empty() => {
+                    (stem, format!(".{ext}"))
+                }
+                _ => (name, String::new()),
+            };
+            let free = std::iter::once(name.to_owned())
+                .chain((1..).map(|n| format!("{stem} ({n}){extension}")))
+                .find(|candidate| server.live_child_named(parent_uid, candidate).is_none())
+                .expect("an unbounded sequence has a free name");
+            Ok(free)
+        })
+        .await
+    }
+
     fn move_nodes_streaming<'a>(
         &'a self,
         items: Vec<NodeMoveItem>,
@@ -1484,8 +1625,12 @@ impl DriveApi for FakeClient {
     fn landing(&self, uid: &NodeUid) {
         let state = {
             let mut hold = self.0.hold_landing.lock();
+            let any = self.0.hold_any_landing.load(Ordering::SeqCst);
             match hold.as_ref() {
-                Some(state) if state.uid == *uid => hold.take(),
+                Some(state) if any || state.uid == *uid => {
+                    self.0.hold_any_landing.store(false, Ordering::SeqCst);
+                    hold.take()
+                }
                 _ => None,
             }
         };
@@ -1506,6 +1651,42 @@ impl DriveApi for FakeClient {
         .await
     }
 
+    async fn enumerate_devices(&self) -> Result<Vec<Computer>> {
+        self.request(false, |server| {
+            Ok((0..server.devices.len())
+                .map(|n| server.computer(n))
+                .collect())
+        })
+        .await
+    }
+
+    async fn create_device(&self, name: &str, device_type: DeviceType) -> Result<Computer> {
+        self.request(true, |server| {
+            // A device root has no parent: like on Drive, it is not in My files.
+            // It is listed at once, as the My files root is: the listing lag is
+            // about children appearing, and the daemon lists the new root next.
+            let root = server.mint_uid();
+            let now = now_secs();
+            server.nodes.insert(
+                root.clone(),
+                vec![(
+                    Instant::now() - HISTORY,
+                    Some(Remote {
+                        parent: None,
+                        name: name.to_owned(),
+                        trashed: false,
+                        created: now,
+                        modified: now,
+                        file: None,
+                    }),
+                )],
+            );
+            server.devices.push((name.to_owned(), device_type, root));
+            Ok(server.computer(server.devices.len() - 1))
+        })
+        .await
+    }
+
     async fn enumerate_trash_node_uids(&self) -> Result<Vec<NodeUid>> {
         self.request(false, |server| {
             Ok(server

crates/pdfs-fuse/src/state.rs

@@ -212,6 +212,31 @@ pub(crate) fn lid_ino(lid: i64) -> u64 {
     lid.unsigned_abs() + crate::ROOT_INO
 }
 
+/// The inodes of the stored nodes among `nodes`, from their local ids, for
+/// [`State::intern_batch_with_inos`]. Called before the state lock is taken;
+/// a node that already has a row keeps its id. Empty when the database fails,
+/// which leaves the allocation to the lock holder, as before.
+pub(crate) fn inos_for(db: &Db, nodes: &[Node]) -> HashMap<NodeUid, u64> {
+    let stored: Vec<&Node> = nodes
+        .iter()
+        .filter(|node| !crate::r#virtual::is_virtual_uid(&node.uid))
+        .collect();
+    if stored.is_empty() {
+        return HashMap::new();
+    }
+    match db.lids_for(&stored) {
+        Ok(lids) => stored
+            .iter()
+            .zip(lids)
+            .map(|(node, lid)| (node.uid.clone(), lid_ino(lid)))
+            .collect(),
+        Err(error) => {
+            warn!(%error, "no local ids before the listing; allocating them under the lock");
+            HashMap::new()
+        }
+    }
+}
+
 /// The local id of the node at inode `ino`, the inverse of [`lid_ino`]:
 /// `None` for the root and a fallback inode.
 pub(crate) fn ino_lid(ino: u64) -> Option<i64> {
@@ -241,6 +266,11 @@ pub(crate) struct State {
     pub(crate) next_ino: u64,
     /// Shared write state keyed by inode. Concurrent writers share the scratch file.
     pub(crate) active_writes: HashMap<u64, WriteHandle>,
+    /// Inodes whose last write handle `release` has taken out of
+    /// [`State::active_writes`] and is still queueing. `close(2)` returns
+    /// before that, and in between the edit is in neither the handles nor the
+    /// queue, so a check for changes not on Drive yet looks here too.
+    pub(crate) releasing: HashSet<u64>,
     /// Maps file handle id (fh) to inode (ino). Read-only opens use fh 0 and
     /// have no entry here.
     pub(crate) handles: HashMap<u64, u64>,
@@ -403,6 +433,7 @@ impl State {
             roots: HashSet::new(),
             next_ino: FALLBACK_INO,
             active_writes: HashMap::new(),
+            releasing: HashSet::new(),
             handles: HashMap::new(),
             next_fh: 1,
             dir_snapshots: HashMap::new(),
@@ -1074,20 +1105,34 @@ impl State {
     ///
     /// This is what keeps `ls` on a large folder quick: one commit for the
     /// listing, rather than one autocommit — and one fsync — per child.
-    pub(crate) fn intern_batch(&mut self, parent: u64, mut nodes: Vec<Node>) -> Vec<u64> {
+    #[cfg(test)]
+    pub(crate) fn intern_batch(&mut self, parent: u64, nodes: Vec<Node>) -> Vec<u64> {
+        self.intern_batch_with_inos(parent, nodes, HashMap::new())
+    }
+
+    /// [`State::intern_batch`], with inodes for new entries that the caller
+    /// allocated before it took the lock, from [`inos_for`]. Allocating them
+    /// is a write transaction, and under the lock every inline handler of
+    /// every mount waited for it (`docs/BUGS.md` B221). A node missing from
+    /// `inos` still gets one here.
+    pub(crate) fn intern_batch_with_inos(
+        &mut self,
+        parent: u64,
+        mut nodes: Vec<Node>,
+        mut inos: HashMap<NodeUid, u64>,
+    ) -> Vec<u64> {
         for node in &mut nodes {
             self.keep_revision_mtime(node);
         }
         self.outbox.push(DbWrite::Upsert(nodes.clone()));
         let fresh: Vec<&Node> = nodes
             .iter()
-            .filter(|node| !self.by_uid.contains_key(&node.uid))
+            .filter(|node| !self.by_uid.contains_key(&node.uid) && !inos.contains_key(&node.uid))
             .collect();
-        let mut inos = if fresh.is_empty() {
-            HashMap::new()
-        } else {
-            self.new_inos(&fresh)
-        };
+        if !fresh.is_empty() {
+            let allocated = self.new_inos(&fresh);
+            inos.extend(allocated);
+        }
         nodes
             .into_iter()
             .map(|node| {
@@ -1098,6 +1143,13 @@ impl State {
             .collect()
     }
 
+    /// Record `uid`'s listing as complete once the lock is released, after the
+    /// rows of its children: written the other way round, a crash between the
+    /// two left a folder marked complete with no children to show.
+    pub(crate) fn record_listed(&mut self, uid: NodeUid) {
+        self.outbox.push(DbWrite::SetListed(uid, true));
+    }
+
     /// Check if a directory inode has any child nodes in memory or in the database.
     pub(crate) fn has_children(&self, parent: u64) -> bool {
         // A resident listing is authoritative even when empty. Falling through
@@ -1467,6 +1519,44 @@ mod tests {
         );
     }
 
+    /// A listing's inodes are allocated before the lock is taken, and are the
+    /// ones a node would get under it (`docs/BUGS.md` B221).
+    #[test]
+    fn inodes_allocated_before_the_lock_are_the_ones_the_node_keeps() {
+        let (mut st, _dir) = state();
+        let db = st.db.clone();
+        let listing = vec![
+            node("a", "root", "a.txt", false),
+            node("b", "root", "b.txt", false),
+        ];
+        let early = inos_for(&db, &listing);
+        assert_eq!(early.len(), 2);
+        let inos = st.intern_batch_with_inos(0, listing, early.clone());
+        assert_eq!(inos, [early[&uid("a")], early[&uid("b")]]);
+        st.flush_outbox();
+
+        let mut restarted = State::new(db, HashMap::new());
+        assert_eq!(
+            restarted.intern(0, node("b", "root", "b.txt", false)),
+            early[&uid("b")]
+        );
+    }
+
+    /// The listing is recorded complete with its children's rows, when the
+    /// lock goes, never ahead of them.
+    #[test]
+    fn a_listing_is_recorded_complete_after_its_children() {
+        let (mut st, _dir) = state();
+        let root = st.intern(0, node("root", "none", "root", true));
+        st.flush_outbox();
+        st.intern_batch(root, vec![node("a", "root", "a.txt", false)]);
+        st.record_listed(uid("root"));
+        assert!(st.db.children_if_listed(&uid("root")).unwrap().is_none());
+        st.flush_outbox();
+        let kids = st.db.children_if_listed(&uid("root")).unwrap().unwrap();
+        assert_eq!(kids.len(), 1);
+    }
+
     /// Audit A5. Moving a file out of a folder leaves that folder's DB row
     /// claiming a complete listing, so once the hot cache drops it, remote
     /// changes under it stop being seen. `relocate` has to clear both sides.

crates/pdfs-fuse/src/supervisor.rs

@@ -36,6 +36,11 @@ const TICK: Duration = Duration::from_secs(15);
 /// would train everyone to ignore the real one.
 const STALL_AFTER: Duration = Duration::from_secs(120);
 
+/// How long a sync pass may go without reporting progress before it is called
+/// out. Much longer than [`STALL_AFTER`]: one large file in a pass reports
+/// nothing until its whole transfer is done.
+const SYNC_STALL_AFTER: Duration = Duration::from_secs(900);
+
 /// How often resident size goes into the log.
 const RSS_EVERY: Duration = Duration::from_secs(300);
 
@@ -137,6 +142,26 @@ fn report_stalls(report: &pdfs_core::control::Diagnostics, last_completed: (u64,
             "the transfer lane has not completed a job since the last check"
         );
     }
+    // The engine is one thread for every synced folder, so a dead or stuck one
+    // stops all of them while the worker pool looks idle (B259).
+    if let Some(sync) = &report.sync {
+        if !sync.running {
+            stalled = true;
+            warn!(
+                "the sync engine is not running; synced folders do not sync until the daemon restarts"
+            );
+        } else if let Some(folder) = sync.pass_folder
+            && sync.pass_idle_secs >= SYNC_STALL_AFTER.as_secs()
+        {
+            stalled = true;
+            warn!(
+                folder,
+                age_secs = sync.pass_age_secs,
+                idle_secs = sync.pass_idle_secs,
+                "a sync pass has not reported progress for a long time"
+            );
+        }
+    }
     stalled
 }
 
@@ -169,7 +194,7 @@ fn probe(control_socket: &Path) -> bool {
 #[cfg(test)]
 mod tests {
     use super::*;
-    use pdfs_core::control::{Diagnostics, InflightRequest, WorkerState};
+    use pdfs_core::control::{Diagnostics, InflightRequest, SyncEngineState, WorkerState};
 
     fn busy_worker(age_secs: u64) -> WorkerState {
         WorkerState {
@@ -226,4 +251,45 @@ mod tests {
         assert!(!report_stalls(&report, (0, 30)));
         assert!(report_stalls(&report, (0, 40)));
     }
+
+    fn with_sync(sync: SyncEngineState) -> Diagnostics {
+        Diagnostics {
+            sync: Some(sync),
+            ..Default::default()
+        }
+    }
+
+    /// A sync engine that has ended stops every synced folder while the
+    /// workers look idle, which is what issue #53 looked like (B259).
+    #[test]
+    fn a_stopped_sync_engine_is_a_stall() {
+        assert!(report_stalls(
+            &with_sync(SyncEngineState::default()),
+            (0, 0)
+        ));
+    }
+
+    /// A pass that keeps reporting progress is working, however long it runs;
+    /// one that has gone quiet past the threshold is not.
+    #[test]
+    fn only_a_quiet_sync_pass_is_a_stall() {
+        let busy = SyncEngineState {
+            running: true,
+            pass_folder: Some(3),
+            pass_age_secs: SYNC_STALL_AFTER.as_secs() * 4,
+            pass_idle_secs: 5,
+            panics: 0,
+        };
+        assert!(!report_stalls(&with_sync(busy.clone()), (0, 0)));
+        let quiet = SyncEngineState {
+            pass_idle_secs: SYNC_STALL_AFTER.as_secs(),
+            ..busy
+        };
+        assert!(report_stalls(&with_sync(quiet), (0, 0)));
+        let idle = SyncEngineState {
+            running: true,
+            ..Default::default()
+        };
+        assert!(!report_stalls(&with_sync(idle), (0, 0)));
+    }
 }

crates/pdfs-fuse/src/sweep.rs

@@ -37,10 +37,12 @@ const CONFLICT_SWEEP_INTERVAL: Duration = Duration::from_secs(300);
 /// fresh mount does at startup (hydrate, recover, initial enumeration).
 const CONFLICT_SWEEP_WARMUP: Duration = Duration::from_secs(30);
 
-/// Strip a ` (sync-conflict <stamp>)` (optionally `-<n>`) marker from `name`,
-/// returning the original file name it was a copy of. `None` when `name` is not a
-/// conflict copy. Inverse of the `conflict_name` / `conflict_path_with_suffix`
-/// formats, so the two halves of the product agree on what a conflict is.
+/// Strip a ` (sync-conflict <label> <stamp>)` (optionally `-<n>`) marker from
+/// `name`, returning the original file name it was a copy of. The label names
+/// the computer that made the copy (B251); copies made before it have the bare
+/// stamp. `None` when `name` is not a conflict copy. Inverse of the
+/// `conflict_name` / `conflict_path_with_suffix` formats, so the two halves of
+/// the product agree on what a conflict is.
 pub(crate) fn conflict_base_name(name: &str) -> Option<String> {
     const MARKER: &str = " (sync-conflict ";
     let start = name.find(MARKER)?;
@@ -48,6 +50,20 @@ pub(crate) fn conflict_base_name(name: &str) -> Option<String> {
     let close_rel = name[after..].find(')')?;
     let close = after + close_rel;
     let inner = &name[after..close];
+    // A label is one token of the characters `conflict_label_of` keeps.
+    let inner = match inner.rsplit_once(' ') {
+        Some((label, token)) => {
+            let label_ok = !label.is_empty()
+                && label
+                    .chars()
+                    .all(|c| c.is_ascii_alphanumeric() || matches!(c, '-' | '_' | '.'));
+            if !label_ok {
+                return None;
+            }
+            token
+        }
+        None => inner,
+    };
     // The token is `<digits>` or `<digits>-<digits>`; reject anything else so a
     // file that merely happens to contain the phrase is not mistaken for a copy.
     let mut parts = inner.splitn(2, '-');
@@ -486,6 +502,24 @@ mod tests {
             conflict_base_name("notes (sync-conflict 1700-3).txt").as_deref(),
             Some("notes.txt")
         );
+        // Named after the computer that made it (B251).
+        assert_eq!(
+            conflict_base_name("notes (sync-conflict laptop 1700).txt").as_deref(),
+            Some("notes.txt")
+        );
+        assert_eq!(
+            conflict_base_name("notes (sync-conflict my-pc.local 1700-2).txt").as_deref(),
+            Some("notes.txt")
+        );
+        assert_eq!(
+            conflict_base_name(&crate::conflict_name("notes.txt", 1700)).as_deref(),
+            Some("notes.txt")
+        );
+        assert_eq!(
+            conflict_base_name("x (sync-conflict two words 1).txt"),
+            None
+        );
+        assert_eq!(conflict_base_name("x (sync-conflict  1).txt"), None);
         // Not a conflict copy.
         assert_eq!(conflict_base_name("report.xml"), None);
         // Looks close but the token is not a stamp.

crates/pdfs-fuse/src/sync/engine.rs

@@ -1,5 +1,11 @@
 //! Filesystem watcher, polling, and debounce control plane.
 
+use std::panic::AssertUnwindSafe;
+use std::sync::atomic::{AtomicBool, AtomicU64, Ordering};
+
+use pdfs_core::control::SyncEngineState;
+use tracing::error;
+
 use super::*;
 
 /// How long the watcher must go quiet before a burst counts as finished.
@@ -22,7 +28,10 @@ const POLL_INTERVAL: Duration = Duration::from_secs(120);
 /// per-item work is a network round-trip, so a folder with thousands of files is
 /// unusable done one-at-a-time; this bounds concurrency like the bulk-upload
 /// engine does.
-pub(super) const SYNC_CONCURRENCY: usize = 8;
+pub(crate) const SYNC_CONCURRENCY: usize = 8;
+/// How long after a failed watch the engine tries the watches again. Each try
+/// walks the folder's whole tree, so not on every burst.
+const REWATCH_RETRY: Duration = Duration::from_secs(600);
 
 /// A message to the sync engine's control thread.
 pub(crate) enum SyncMsg {
@@ -53,30 +62,159 @@ pub(crate) fn spawn(core: Core, rx: Receiver<SyncMsg>) -> Option<std::thread::Jo
     }
 }
 
+/// Whether the engine is alive and which pass it is on, for
+/// [`Core::diagnostics`] and the supervisor.
+///
+/// A panic in a pass used to end the engine thread. Every later add, sync-now,
+/// file event and poll then went into a channel nobody read, the folder stayed
+/// `syncing`, and nothing said so until a restart (`docs/BUGS.md` B259).
+#[derive(Default)]
+pub(crate) struct EngineHealth {
+    running: AtomicBool,
+    pass: Mutex<Option<PassClock>>,
+    panics: AtomicU64,
+}
+
+#[derive(Clone, Copy)]
+struct PassClock {
+    folder: i64,
+    started: Instant,
+    moved: Instant,
+}
+
+impl EngineHealth {
+    /// Note that the running pass reported progress.
+    pub(crate) fn moved(&self) {
+        if let Some(pass) = self.pass.lock().as_mut() {
+            pass.moved = Instant::now();
+        }
+    }
+
+    /// The engine's state now. `try_lock`, like the rest of the diagnostics:
+    /// a report must not wait on the thing it reports about.
+    pub(crate) fn report(&self) -> SyncEngineState {
+        let pass = self.pass.try_lock().and_then(|pass| *pass);
+        SyncEngineState {
+            running: self.running.load(Ordering::Relaxed),
+            pass_folder: pass.map(|p| p.folder),
+            pass_age_secs: pass.map_or(0, |p| p.started.elapsed().as_secs()),
+            pass_idle_secs: pass.map_or(0, |p| p.moved.elapsed().as_secs()),
+            panics: self.panics.load(Ordering::Relaxed),
+        }
+    }
+
+    /// Run `pass` over `folder` as the current pass. Returns `false` when it
+    /// panicked: the panic ends that pass, not the engine.
+    pub(super) fn contain(&self, folder: i64, pass: impl FnOnce()) -> bool {
+        let now = Instant::now();
+        *self.pass.lock() = Some(PassClock {
+            folder,
+            started: now,
+            moved: now,
+        });
+        let finished = std::panic::catch_unwind(AssertUnwindSafe(pass)).is_ok();
+        *self.pass.lock() = None;
+        if !finished {
+            self.panics.fetch_add(1, Ordering::Relaxed);
+        }
+        finished
+    }
+}
+
+/// Marks the engine running for as long as it lives.
+pub(super) struct Running<'a>(&'a EngineHealth);
+
+impl<'a> Running<'a> {
+    pub(super) fn start(health: &'a EngineHealth) -> Self {
+        health.running.store(true, Ordering::Relaxed);
+        Self(health)
+    }
+}
+
+impl Drop for Running<'_> {
+    fn drop(&mut self) {
+        self.0.running.store(false, Ordering::Relaxed);
+        if std::thread::panicking() {
+            error!("sync engine stopped by a panic; nothing syncs until the daemon restarts");
+        }
+    }
+}
+
+/// One folder's pass, contained: a panic in it sets the folder to `error` and
+/// leaves the engine running for the next one.
+fn run_pass(core: &Core, folder: &StoredSyncFolder) {
+    if core
+        .sync_engine
+        .contain(folder.id, || core.reconcile_folder(folder))
+    {
+        return;
+    }
+    core.progress_end(folder.id);
+    let _ = core
+        .db
+        .sync_folder_set_state(folder.id, "error", folder.last_sync);
+    error!(
+        id = folder.id,
+        path = %folder.local_path,
+        "sync: pass panicked; the folder is set to error and tried again on the next poll"
+    );
+    core.log_activity(
+        ActivityKind::Sync,
+        format!("sync failed for {}", base_name(&folder.local_path)),
+        "an internal error stopped the pass; it is tried again on the next poll",
+        false,
+    );
+}
+
+/// The pass a `Reconcile(id)` asked for. A folder removed since, or one the
+/// database cannot read, is said so rather than dropped in silence.
+fn run_pass_by_id(core: &Core, id: i64) {
+    match core.db.sync_folder_get(id) {
+        Ok(Some(folder)) => run_pass(core, &folder),
+        Ok(None) => debug!(id, "sync: folder removed before its pass; skipping"),
+        Err(e) => warn!(id, error = ?e, "sync: cannot read folder; skipping its pass"),
+    }
+}
+
 /// The engine control loop. Single-threaded so reconcile passes never overlap.
 fn engine_loop(core: Core, rx: Receiver<SyncMsg>) {
+    let health = core.sync_engine.clone();
+    let _running = Running::start(&health);
     // Paths the watcher currently covers, mapped to their folder id, so an event
     // path can be resolved back to the folder it belongs to.
-    let watched: Mutex<Vec<(PathBuf, i64)>> = Mutex::new(Vec::new());
+    let watched: Arc<Mutex<Vec<(PathBuf, i64)>>> = Arc::new(Mutex::new(Vec::new()));
 
     let tx_events = core.sync_tx.clone();
-    let mut watcher =
-        match notify::recommended_watcher(move |res: notify::Result<notify::Event>| {
-            let Ok(event) = res else { return };
-            // Ignore pure metadata/access noise; content changes are what matter.
-            if matches!(event.kind, notify::EventKind::Access(_)) {
-                return;
-            }
-            let _ = tx_events.send(SyncMsg::ReconcileAll);
-        }) {
-            Ok(w) => w,
+    let watched_events = watched.clone();
+    let handler = move |res: notify::Result<notify::Event>| {
+        let event = match res {
+            Ok(event) => event,
+            // Running out of inotify watches for a new subfolder, say: that
+            // subfolder's changes are then found by the poll only (B262).
             Err(e) => {
-                warn!(error = %e, "filesystem watcher unavailable; sync is poll-only");
-                // Still run the loop so polling and explicit SyncNow work.
-                poll_only_loop(&core, rx);
+                warn!(error = %e, "sync: filesystem watcher error");
                 return;
             }
         };
+        // Ignore pure metadata/access noise; content changes are what matter.
+        if matches!(event.kind, notify::EventKind::Access(_)) {
+            return;
+        }
+        let msg = event_target(&watched_events.lock(), &event.paths);
+        let _ = tx_events.send(msg);
+    };
+    // The local walk skips symlinks, so following them here would only watch
+    // trees outside the folder, and run passes over it for changes made there.
+    let config = notify::Config::default().with_follow_symlinks(false);
+    let mut watcher = match notify::RecommendedWatcher::new(handler, config) {
+        Ok(w) => w,
+        Err(e) => {
+            warn!(error = %e, "filesystem watcher unavailable; sync is poll-only");
+            // Still run the loop so polling and explicit SyncNow work.
+            poll_only_loop(&core, rx);
+            return;
+        }
+    };
 
     // Periodic remote poll.
     {
@@ -94,8 +232,9 @@ fn engine_loop(core: Core, rx: Receiver<SyncMsg>) {
             .ok();
     }
 
-    rewatch(&core, &mut watcher, &watched);
-    reconcile_all(&core);
+    let mut unwatched = rewatch(&core, &mut watcher, &watched);
+    let mut last_rewatch = Instant::now();
+    run_burst(&core, &HashSet::new(), true);
 
     while let Ok(msg) = rx.recv() {
         let mut ids: HashSet<i64> = HashSet::new();
@@ -108,21 +247,16 @@ fn engine_loop(core: Core, rx: Receiver<SyncMsg>) {
             return;
         }
 
+        // A folder whose watch failed is tried again now and then, not only
+        // when the folder set changes.
+        if unwatched && last_rewatch.elapsed() >= REWATCH_RETRY {
+            do_rewatch = true;
+        }
         if do_rewatch {
-            rewatch(&core, &mut watcher, &watched);
-        }
-        if all {
-            reconcile_all(&core);
-        } else {
-            for id in ids {
-                if core.sync_paused() {
-                    break;
-                }
-                if let Ok(Some(folder)) = core.db.sync_folder_get(id) {
-                    core.reconcile_folder(&folder);
-                }
-            }
+            unwatched = rewatch(&core, &mut watcher, &watched);
+            last_rewatch = Instant::now();
         }
+        run_burst(&core, &ids, all);
     }
 }
 
@@ -139,7 +273,7 @@ fn poll_only_loop(core: &Core, rx: Receiver<SyncMsg>) {
             }
         });
     }
-    reconcile_all(core);
+    run_burst(core, &HashSet::new(), true);
     while let Ok(msg) = rx.recv() {
         let mut ids: HashSet<i64> = HashSet::new();
         let mut all = false;
@@ -150,21 +284,59 @@ fn poll_only_loop(core: &Core, rx: Receiver<SyncMsg>) {
             info!("sync engine stopping");
             return;
         }
-        if all {
-            reconcile_all(core);
-        } else {
-            for id in ids {
-                if core.sync_paused() {
-                    break;
-                }
-                if let Ok(Some(folder)) = core.db.sync_folder_get(id) {
-                    core.reconcile_folder(&folder);
-                }
+        run_burst(core, &ids, all);
+    }
+}
+
+/// Run the passes one burst asked for: the folders named by id, then, when the
+/// burst also holds a `ReconcileAll`, every other folder.
+///
+/// The named folders go first. A poll's `ReconcileAll` in the same burst used
+/// to take their place, and a folder just added, which has the highest id,
+/// waited behind a full pass over every other folder (`docs/BUGS.md` B260).
+///
+/// Skipped while sync is paused, and cut short when a pause lands between
+/// passes: the resume sends a fresh [`SyncMsg::ReconcileAll`], which walks
+/// everything the watcher reported meanwhile.
+fn run_burst(core: &Core, ids: &HashSet<i64>, all: bool) {
+    if core.sync_paused() {
+        debug!("sync: paused, skipping reconcile");
+        return;
+    }
+    let folders = if all {
+        match core.db.sync_folder_list() {
+            Ok(folders) => folders,
+            Err(e) => {
+                warn!(error = ?e, "sync: cannot list folders");
+                Vec::new()
             }
         }
+    } else {
+        Vec::new()
+    };
+    let listed: Vec<i64> = folders.iter().map(|f| f.id).collect();
+    for id in burst_order(ids, &listed) {
+        if core.sync_paused() {
+            break;
+        }
+        // A folder named by id is read again: it may have been added or
+        // changed after the list was read.
+        match folders.iter().find(|f| f.id == id) {
+            Some(folder) if !ids.contains(&id) => run_pass(core, folder),
+            _ => run_pass_by_id(core, id),
+        }
     }
 }
 
+/// The order of a burst's passes: the folders named by id, lowest first, then
+/// the rest of `listed` in its own order.
+pub(super) fn burst_order(ids: &HashSet<i64>, listed: &[i64]) -> Vec<i64> {
+    let mut order: Vec<i64> = ids.iter().copied().collect();
+    order.sort_unstable();
+    order.extend(listed.iter().copied().filter(|id| !ids.contains(id)));
+    order
+}
+
 /// Absorb the rest of an event burst, returning once the watcher has been quiet
 /// for `quiet` or `cap` has elapsed since the first event — whichever comes
 /// first. The caller has already classified the event that opened the burst.
@@ -236,33 +408,37 @@ pub(super) fn classify(
     true
 }
 
-/// Reconcile every mirror folder in turn. Skipped while sync is paused: the
-/// resume sends a fresh [`SyncMsg::ReconcileAll`], which walks everything the
-/// watcher reported meanwhile.
-fn reconcile_all(core: &Core) {
-    if core.sync_paused() {
-        debug!("sync: paused, skipping reconcile");
-        return;
-    }
-    let folders = match core.db.sync_folder_list() {
-        Ok(f) => f,
-        Err(e) => {
-            warn!(error = ?e, "sync: cannot list folders");
-            return;
-        }
-    };
-    for folder in folders {
-        core.reconcile_folder(&folder);
+/// The reconcile a watcher event asks for: the one mirror folder all its paths
+/// lie in, so an edit in one folder does not walk every other one too. An event
+/// that spans folders, or that no watched folder claims (a watch list a moment
+/// out of date), falls back to every folder.
+pub(super) fn event_target(watched: &[(PathBuf, i64)], paths: &[PathBuf]) -> SyncMsg {
+    let mut ids = paths.iter().map(|path| {
+        watched
+            .iter()
+            .filter(|(root, _)| path.starts_with(root))
+            // The deepest root, should one mirror folder sit inside another.
+            .max_by_key(|(root, _)| root.components().count())
+            .map(|(_, id)| *id)
+    });
+    match ids.next() {
+        Some(Some(first)) if ids.all(|id| id == Some(first)) => SyncMsg::Reconcile(first),
+        _ => SyncMsg::ReconcileAll,
     }
 }
 
 /// Bring the filesystem watches in line with the current mirror-folder set:
-/// watch newly-added folders, drop removed ones.
+/// watch newly-added folders, drop removed ones. Returns whether a folder is
+/// left unwatched because its watch failed.
+///
+/// The watch calls run on a copy, outside the lock: the watcher's event
+/// callback takes the same lock, and a backend that hands a watch request to
+/// its event thread and waits for the answer would deadlock against it.
 fn rewatch(
     core: &Core,
     watcher: &mut notify::RecommendedWatcher,
     watched: &Mutex<Vec<(PathBuf, i64)>>,
-) {
+) -> bool {
     let want: Vec<(PathBuf, i64)> = match core.db.sync_folder_list() {
         Ok(f) => f
             .into_iter()
@@ -271,29 +447,60 @@ fn rewatch(
             .collect(),
         Err(e) => {
             warn!(error = ?e, "sync: cannot list folders to watch");
-            return;
+            return false;
         }
     };
-    let mut have = watched.lock();
+    let mut have = watched.lock().clone();
     // Drop watches no longer wanted.
-    have.retain(|(path, _)| {
-        if want.iter().any(|(p, _)| p == path) {
-            true
-        } else {
-            let _ = watcher.unwatch(path);
-            false
-        }
-    });
+    for path in keep_wanted(&mut have, &want) {
+        let _ = watcher.unwatch(&path);
+    }
     // Add newly wanted watches.
+    let mut failed = false;
     for (path, id) in &want {
         if have.iter().any(|(p, _)| p == path) {
             continue;
         }
         match watcher.watch(path, RecursiveMode::Recursive) {
             Ok(()) => have.push((path.clone(), *id)),
-            Err(e) => warn!(path = %path.display(), error = %e, "sync: watch failed"),
+            Err(e) => {
+                // A recursive watch that fails partway keeps the watches it had
+                // added. Their events would match no folder and run a pass over
+                // every one, and they hold watches the next folder needs (B262).
+                let _ = watcher.unwatch(path);
+                failed = true;
+                warn!(
+                    path = %path.display(),
+                    error = %e,
+                    "sync: watch failed; the poll finds this folder's changes until a retry \
+                     works. A low fs.inotify.max_user_watches is the usual cause"
+                );
+            }
         }
     }
+    *watched.lock() = have;
+    failed
+}
+
+/// Keep the watches in `have` that `want` still asks for, and return the paths
+/// of the others, to unwatch.
+///
+/// A path is matched alone, but takes the id `want` gives it: a folder removed
+/// and added again in one burst keeps its watch, and its events go to the new
+/// row rather than to the removed one (`docs/BUGS.md` B272).
+pub(super) fn keep_wanted(have: &mut Vec<(PathBuf, i64)>, want: &[(PathBuf, i64)]) -> Vec<PathBuf> {
+    let mut dropped = Vec::new();
+    have.retain_mut(|(path, id)| match want.iter().find(|(p, _)| p == path) {
+        Some((_, wanted)) => {
+            *id = *wanted;
+            true
+        }
+        None => {
+            dropped.push(path.clone());
+            false
+        }
+    });
+    dropped
 }
 
 // ---- reconcile ------------------------------------------------------------

crates/pdfs-fuse/src/sync/model.rs

@@ -83,6 +83,46 @@ pub(super) struct RemoteItem {
     pub(super) is_dir: bool,
     pub(super) mtime: i64,
     pub(super) size: i64,
+    /// The active revision's id. The light walk carries it for every file, so
+    /// it is the signal that tells another client's new revision from a link
+    /// merely re-stamped.
+    pub(super) revision: Option<String>,
+    /// The active revision's content SHA-1, read only for files the walk
+    /// enumerated in full (no baseline, or a moved mtime). `None` is never
+    /// proof of anything.
+    pub(super) sha1: Option<String>,
+}
+
+/// What a pass saw of a remote file: the signature its baseline records once
+/// the file is synced, and what an upload checks Drive still holds before it
+/// supersedes it.
+#[derive(Clone, Debug, PartialEq, Eq)]
+pub(super) struct RemoteSeen {
+    pub(super) mtime: i64,
+    pub(super) size: i64,
+    pub(super) revision: Option<String>,
+}
+
+impl RemoteSeen {
+    /// Whether `node` is still the revision this was taken from. The revision
+    /// id decides it when both sides have one; otherwise the modification time
+    /// and size, which is all a baseline row from before schema 44 holds.
+    pub(super) fn still_current(&self, node: &Node) -> bool {
+        match (&self.revision, crate::node_revision_id(node)) {
+            (Some(seen), Some(now)) => *seen == now,
+            _ => (self.mtime, self.size) == remote_file_sig(node),
+        }
+    }
+}
+
+impl From<&RemoteItem> for RemoteSeen {
+    fn from(item: &RemoteItem) -> Self {
+        Self {
+            mtime: item.mtime,
+            size: item.size,
+            revision: item.revision.clone(),
+        }
+    }
 }
 
 /// The result of a reconcile pass: what it moved, how many paths were kept as
@@ -98,6 +138,11 @@ pub(super) struct Outcome {
     pub(super) errors: usize,
     /// Files skipped because another process held them open for writing.
     pub(super) deferred: usize,
+    /// Paths the local scan could not read, left out of the pass. Not part of
+    /// [`is_empty`](Self::is_empty) or the summary: an unreadable folder stays
+    /// unreadable from one poll to the next, so the pass reports it once, when
+    /// the set changes, rather than on every poll.
+    pub(super) unscanned: Vec<String>,
 }
 
 impl Outcome {
@@ -108,7 +153,7 @@ impl Outcome {
             Applied::Uploaded => self.uploaded += 1,
             Applied::Downloaded => self.downloaded += 1,
             Applied::Conflict => self.conflicts += 1,
-            Applied::Vanished => {}
+            Applied::Vanished | Applied::Adopted => {}
         }
     }
 
@@ -152,10 +197,16 @@ pub(super) enum Pending {
     CreateDir { rel: String, parent: NodeUid },
     /// Upload a brand-new local file into `parent`.
     UploadNew { rel: String, parent: NodeUid },
-    /// Upload a changed local file as a new revision of `uid`.
-    UploadRevision { rel: String, uid: NodeUid },
-    /// Download remote `uid` to the local path, stamping `mtime`. `size` is the
-    /// remote's reported size, used as the transfer's expected total.
+    /// Upload a changed local file as a new revision of `uid`, if Drive still
+    /// holds the revision `seen` describes (B249).
+    UploadRevision {
+        rel: String,
+        uid: NodeUid,
+        seen: RemoteSeen,
+    },
+    /// Download remote `uid` to the local path, stamping `seen.mtime`.
+    /// `seen.size` is the remote's reported size, used as the transfer's
+    /// expected total.
     ///
     /// `local` is what the planning walk saw at this path, or `None` if nothing
     /// was there. A download can run for minutes, so the apply step revalidates
@@ -165,16 +216,26 @@ pub(super) enum Pending {
     Download {
         rel: String,
         uid: NodeUid,
-        mtime: i64,
-        size: i64,
+        seen: RemoteSeen,
         local: Option<LocalSig>,
     },
+    /// First sync of a path present on both sides at the same size, with a
+    /// digest on Drive: hash the local file, and record the baseline if it holds
+    /// the same bytes. A different file of the same size goes the way of
+    /// [`Pending::Conflict`]: two machines syncing one folder must not read as
+    /// in step while they hold different content.
+    Adopt {
+        rel: String,
+        uid: NodeUid,
+        seen: RemoteSeen,
+        sha1: String,
+        local: LocalSig,
+    },
     /// Both sides changed: set the local copy aside, then download remote `uid`.
     Conflict {
         rel: String,
         uid: NodeUid,
-        mtime: i64,
-        size: i64,
+        seen: RemoteSeen,
     },
     /// Both sides changed during a [`push pass`](Core::push_pass): upload the local
     /// copy into `parent` under a conflict name, leaving the remote file as it is.
@@ -189,6 +250,7 @@ impl Pending {
             | Pending::UploadNew { rel, .. }
             | Pending::UploadRevision { rel, .. }
             | Pending::Download { rel, .. }
+            | Pending::Adopt { rel, .. }
             | Pending::Conflict { rel, .. }
             | Pending::PushConflict { rel, .. } => rel,
         }
@@ -201,7 +263,9 @@ impl Pending {
             Pending::UploadNew { .. }
             | Pending::UploadRevision { .. }
             | Pending::PushConflict { .. } => ActivityKind::Upload,
-            Pending::Download { .. } | Pending::Conflict { .. } => ActivityKind::Download,
+            Pending::Download { .. } | Pending::Adopt { .. } | Pending::Conflict { .. } => {
+                ActivityKind::Download
+            }
         }
     }
 
@@ -212,6 +276,7 @@ impl Pending {
             Pending::UploadNew { .. } => "new file",
             Pending::UploadRevision { .. } => "new version",
             Pending::Download { .. } => "from Drive",
+            Pending::Adopt { .. } => "already the same on Drive",
             Pending::Conflict { .. } => "local changes kept as a conflict copy",
             Pending::PushConflict { .. } => "local changes uploaded as a conflict copy",
         }

crates/pdfs-fuse/src/sync/planner.rs

@@ -90,33 +90,310 @@ pub(super) fn filter_baseline<'a, B>(
         .collect()
 }
 
-/// Refuse to run a pass whose local side has vanished in its entirety.
+/// The paths a local scan left out because it could not read them: a folder
+/// it has no permission for, an entry that vanished between the listing and
+/// its `stat`, a name that is not UTF-8.
 ///
-/// When every baseline path is absent locally, the likely cause is an unavailable
-/// mount or unreadable folder rather than a deliberate whole-tree deletion.
-/// One surviving path is enough to clear the guard.
+/// A left-out path is not a deleted one. A pass drops everything an entry
+/// covers from classification, exactly as it drops ignored paths, so a
+/// baseline row under an unreadable folder is neither read as a local deletion
+/// nor answered with a download into a folder the pass cannot write. Failing
+/// the whole pass instead is what B55 did, and it left one root-owned folder
+/// stopping every other file in the tree from syncing (B196).
+#[derive(Default)]
+pub(super) struct Unscanned {
+    covered: HashSet<String>,
+    /// The subset worth telling the user about, with why: an entry that only
+    /// vanished mid-scan is not, since the next pass sees it settled.
+    unreadable: Vec<String>,
+}
+
+impl Unscanned {
+    /// Leave out `rel`, which vanished while the scan looked at it.
+    pub(super) fn vanished(&mut self, rel: String) {
+        self.covered.insert(rel);
+    }
+
+    /// Leave out `rel`, which cannot be read for `reason`.
+    pub(super) fn unreadable(&mut self, rel: String, reason: &str) {
+        self.unreadable.push(format!("{rel} ({reason})"));
+        self.covered.insert(rel);
+    }
+
+    /// Whether `rel` is a left-out path or lies under one.
+    pub(super) fn covers(&self, rel: &str) -> bool {
+        if self.covered.is_empty() {
+            return false;
+        }
+        let mut at = rel;
+        loop {
+            if self.covered.contains(at) {
+                return true;
+            }
+            match at.rfind('/') {
+                Some(i) => at = &at[..i],
+                None => return false,
+            }
+        }
+    }
+
+    /// The unreadable paths with their reasons, sorted, for the activity feed.
+    pub(super) fn report(&self) -> Vec<String> {
+        let mut lines = self.unreadable.clone();
+        lines.sort_unstable();
+        lines
+    }
+}
+
+/// The baseline paths a pass can see: [`filter_baseline`], minus everything
+/// under a path the scan could not read. This is the set [`guard_local_wipe`]
+/// checks and the set a push pass reads deletions from, since a path outside
+/// it is absent from the local walk by rule or by failure, never by loss.
+pub(super) fn tracked_baseline<'a, B>(
+    baseline: &'a HashMap<String, B>,
+    rules: &IgnoreRules,
+    unscanned: &Unscanned,
+) -> HashMap<String, &'a B> {
+    let mut tracked = filter_baseline(baseline, rules);
+    tracked.retain(|rel, _| !unscanned.covers(rel));
+    tracked
+}
+
+/// The baseline paths a push pass has to trash on Drive: tracked, and gone
+/// from the local walk. Shallowest first, so a trashed folder takes its
+/// children with it.
+///
+/// Built from [`tracked_baseline`] rather than from the raw baseline. Reading
+/// it raw trashed every synced path that later became ignored, because the walk
+/// skips those, and the switch to on-demand that the push pass runs for then
+/// deleted the local copy too (B197).
+pub(super) fn local_deletions<B, L>(
+    tracked: &HashMap<String, &B>,
+    local: &HashMap<String, L>,
+) -> Vec<String> {
+    let mut missing: Vec<String> = tracked
+        .keys()
+        .filter(|rel| !local.contains_key(*rel))
+        .cloned()
+        .collect();
+    missing.sort_by_key(|p| p.matches('/').count());
+    missing
+}
+
+/// How many tracked paths a folder needs before a mass disappearance, short of
+/// a total one, trips a wipe guard. Below this, a few survivors say little.
+const MASS_LOSS_MIN_PATHS: usize = 20;
+
+/// The share of a large folder's tracked paths that may vanish in one pass, in
+/// tenths, before a wipe guard stops it: 9 of 10 and up is refused.
+const MASS_LOSS_TENTHS: usize = 9;
+
+/// Whether `missing` of `total` tracked paths gone at once looks like a lost
+/// tree rather than deletions. All of them always does. Most of a large
+/// folder does too: one surviving file used to clear the guard, so a
+/// half-mounted disk, or a script that emptied the folder and wrote one file
+/// back, trashed everything else on Drive (B270).
+fn looks_like_a_wipe(missing: usize, total: usize) -> bool {
+    total > 0
+        && (missing == total
+            || (total >= MASS_LOSS_MIN_PATHS && missing * 10 >= total * MASS_LOSS_TENTHS))
+}
+
+/// Refuse to run a pass whose local side has vanished in its entirety, or
+/// nearly so ([`looks_like_a_wipe`]).
+///
+/// When the synced paths are all or nearly all absent locally, the likely
+/// cause is an unavailable mount or unreadable folder rather than a deliberate
+/// deletion of the whole tree.
 pub(super) fn guard_local_wipe<B, L>(
     baseline: &HashMap<String, B>,
     local: &HashMap<String, L>,
 ) -> Result<(), String> {
-    if !baseline.is_empty() && baseline.keys().all(|rel| !local.contains_key(rel)) {
+    let missing = baseline
+        .keys()
+        .filter(|rel| !local.contains_key(*rel))
+        .count();
+    if looks_like_a_wipe(missing, baseline.len()) {
         return Err(format!(
-            "every one of the {} synced paths is missing locally; refusing to trash \
-             them on Drive. Check that the folder is mounted and readable.",
+            "{missing} of the {} synced paths are missing locally; refusing to trash \
+             them on Drive. Check that the folder is mounted and readable; to download \
+             them again, sync the folder from scratch.",
             baseline.len()
         ));
     }
     Ok(())
 }
 
+/// Refuse to run a pass whose remote side has vanished in its entirety, or
+/// nearly so: the remote twin of [`guard_local_wipe`].
+///
+/// An empty or truncated remote walk reads to the planner as "Drive deleted
+/// everything", which a pass answers by deleting the local copies. When all or
+/// nearly all synced paths are gone from Drive at once, a failed listing is far
+/// likelier than a deliberate wipe of the folder, so the pass stops instead.
+pub(super) fn guard_remote_wipe<B, R>(
+    baseline: &HashMap<String, B>,
+    remote: &HashMap<String, R>,
+) -> Result<(), String> {
+    let missing = baseline
+        .keys()
+        .filter(|rel| !remote.contains_key(*rel))
+        .count();
+    if looks_like_a_wipe(missing, baseline.len()) {
+        return Err(format!(
+            "{missing} of the {} synced paths are missing on Proton Drive; refusing to \
+             delete them here. If they were deleted on purpose, remove the folder from sync; \
+             to upload them again, sync the folder from scratch.",
+            baseline.len()
+        ));
+    }
+    Ok(())
+}
+
+/// What a remote walk saw but could not read: a node the SDK left out because
+/// it would not decrypt, or a file whose size could not be read.
+///
+/// A path missing from the walk is read as deleted on Drive, so a pass must
+/// not classify one it only failed to read. Since a node that failed to decrypt
+/// has no name, all a walk can say is that a folder's listing came back short;
+/// every path under that folder that the walk did not return is then left out,
+/// as [`Unscanned`] leaves out what the local scan could not read.
+#[derive(Default)]
+pub(super) struct RemoteGaps {
+    /// Folders whose listing came back with fewer nodes than it named.
+    short: HashSet<String>,
+    /// Paths seen, but whose entry could not be read.
+    unread: HashSet<String>,
+    /// Folders whose listing failed outright, after the SDK's retries. Nothing
+    /// under one is known, so all of it is left out of the pass (B271).
+    unlisted: HashSet<String>,
+}
+
+impl RemoteGaps {
+    /// The listing of `folder` named nodes that did not come back.
+    pub(super) fn short_listing(&mut self, folder: &str) {
+        self.short.insert(folder.to_string());
+    }
+
+    /// `rel` is on Drive, but the walk could not read what it needs of it.
+    pub(super) fn unread(&mut self, rel: String) {
+        self.unread.insert(rel);
+    }
+
+    /// The listing of `folder` failed, so nothing under it was walked.
+    pub(super) fn unlisted(&mut self, folder: &str) {
+        self.unlisted.insert(folder.to_string());
+    }
+
+    pub(super) fn is_empty(&self) -> bool {
+        self.short.is_empty() && self.unread.is_empty() && self.unlisted.is_empty()
+    }
+
+    /// Whether `rel` may be missing from `remote` only because the walk could
+    /// not read it. A path the walk returned is never hidden.
+    pub(super) fn hides<R>(
+        &self,
+        rel: &str,
+        remote: &HashMap<String, R>,
+        remote_dirs: &HashMap<String, NodeUid>,
+    ) -> bool {
+        if self.is_empty() || remote.contains_key(rel) {
+            return false;
+        }
+        if self.unread.contains(rel) {
+            return true;
+        }
+        // The deepest folder the walk did list decides: under a short listing,
+        // anything not returned may be one of the nodes it could not read.
+        let mut at = parent_rel(rel);
+        loop {
+            if remote_dirs.contains_key(at) {
+                return self.short.contains(at) || self.unlisted.contains(at);
+            }
+            if at.is_empty() {
+                return false;
+            }
+            at = parent_rel(at);
+        }
+    }
+
+    /// The folders to name to the user, sorted.
+    pub(super) fn report(&self) -> Vec<String> {
+        let mut lines: Vec<String> = self
+            .short
+            .iter()
+            .map(|rel| {
+                let shown = if rel.is_empty() { "the folder" } else { rel };
+                format!("{shown} (items on Proton Drive that cannot be read)")
+            })
+            .chain(
+                self.unread
+                    .iter()
+                    .map(|rel| format!("{rel} (cannot be read on Proton Drive)")),
+            )
+            .chain(self.unlisted.iter().map(|rel| {
+                format!("{rel} (could not be listed on Proton Drive; tried again next pass)")
+            }))
+            .collect();
+        lines.sort_unstable();
+        lines
+    }
+}
+
+/// Why the remote folder at `rel` must not be trashed although it was deleted
+/// here: something under it is new or changed on Drive since the last sync,
+/// so it is another device's work that this computer has never had.
+///
+/// Trashing the folder would take that work with it, and the next pass would
+/// then delete the copy this pass just downloaded. `None` when everything under
+/// it is exactly what the baseline recorded.
+pub(super) fn remote_subtree_changed(
+    rel: &str,
+    remote: &HashMap<String, RemoteItem>,
+    baseline: &HashMap<String, StoredSyncEntry>,
+) -> Option<String> {
+    let prefix = format!("{rel}/");
+    let mut changed: Vec<&String> = remote
+        .iter()
+        .filter(|(path, _)| path.starts_with(&prefix))
+        .filter(|(path, item)| match baseline.get(*path) {
+            None => true,
+            Some(_) if item.is_dir => false,
+            Some(base) => {
+                remote_sig(base) != Some((item.mtime, item.size))
+                    || revision_moved(Some(base), item.revision.as_deref())
+            }
+        })
+        .map(|(path, _)| path)
+        .collect();
+    changed.sort_unstable();
+    changed
+        .first()
+        .map(|path| format!("{path} is new or changed on Proton Drive"))
+}
+
 /// The size the baseline recorded for `rel`, if its remote signature's mtime
-/// still matches `mtime`.
+/// still matches `mtime` and its revision is still `revision`.
+///
+/// A row without a revision id, while Drive reports one, cannot vouch for the
+/// revision, so the size is read for real. Such a row comes from before
+/// schema 44, or from an upload Drive did not list yet when it was read back.
+/// Another computer's revision in the same second as that upload kept the
+/// modification time, and only the size could show it (B254). The pass then
+/// records the id on the row, so this costs one read per row.
 pub(super) fn unchanged_remote_size(
     baseline: &HashMap<String, StoredSyncEntry>,
     rel: &str,
     mtime: i64,
+    revision: Option<&str>,
 ) -> Option<i64> {
-    match baseline.get(rel).and_then(remote_sig) {
+    let base = baseline.get(rel)?;
+    if revision_moved(Some(base), revision)
+        || (base.remote_revision_id.is_none() && revision.is_some())
+    {
+        return None;
+    }
+    match remote_sig(base) {
         Some((recorded, size)) if recorded == mtime => Some(size),
         _ => None,
     }
@@ -131,6 +408,17 @@ pub(super) fn join_rel(prefix: &str, name: &str) -> String {
     }
 }
 
+/// Whether Drive's active revision `now` is not the one the baseline row was
+/// synced at. Only a revision id on both sides can say so; a row from before
+/// schema 44, or a node read without one, leaves it to the modification time
+/// and size.
+pub(super) fn revision_moved(base: Option<&StoredSyncEntry>, now: Option<&str>) -> bool {
+    match (base.and_then(|b| b.remote_revision_id.as_deref()), now) {
+        (Some(recorded), Some(now)) => recorded != now,
+        _ => false,
+    }
+}
+
 /// The stored remote signature of a baseline row, if it has one.
 pub(super) fn remote_sig(e: &StoredSyncEntry) -> Option<(i64, i64)> {
     match (&e.remote_rev, &e.remote_hash) {
@@ -161,7 +449,8 @@ pub(super) fn rel_to_path(rel: &str) -> PathBuf {
     rel.split('/').collect()
 }
 
-/// The name for a conflict copy of `path`, e.g. `notes (sync-conflict 1700000000).txt`.
+/// The name for a conflict copy of `path`, e.g.
+/// `notes (sync-conflict laptop 1700000000).txt`.
 #[cfg(test)]
 pub(super) fn conflict_path(path: &Path, stamp: i64) -> PathBuf {
     conflict_path_with_suffix(path, stamp, 0)
@@ -170,16 +459,17 @@ pub(super) fn conflict_path(path: &Path, stamp: i64) -> PathBuf {
 /// As [`conflict_path`], with a deterministic suffix used when that name already
 /// exists. This keeps conflict preservation from ever replacing an older copy.
 pub(super) fn conflict_path_with_suffix(path: &Path, stamp: i64, suffix: u32) -> PathBuf {
+    conflict_path_as(path, crate::conflict_label(), stamp, suffix)
+}
+
+/// [`conflict_path_with_suffix`] with the machine's label given.
+pub(super) fn conflict_path_as(path: &Path, label: &str, stamp: i64, suffix: u32) -> PathBuf {
     let stem = path.file_stem().and_then(|s| s.to_str()).unwrap_or("file");
     let ext = path.extension().and_then(|s| s.to_str());
-    let suffix = if suffix == 0 {
-        String::new()
-    } else {
-        format!("-{suffix}")
-    };
+    let tag = crate::conflict_tag(label, stamp, suffix);
     let name = match ext {
-        Some(ext) => format!("{stem} (sync-conflict {stamp}{suffix}).{ext}"),
-        None => format!("{stem} (sync-conflict {stamp}{suffix})"),
+        Some(ext) => format!("{stem} (sync-conflict {tag}).{ext}"),
+        None => format!("{stem} (sync-conflict {tag})"),
     };
     match path.parent() {
         Some(dir) => dir.join(name),
@@ -200,11 +490,14 @@ pub(super) enum FilePlan {
     DeleteLocal,
     DeleteRemote,
     ForgetBaseline,
-    /// First sync of a file that already exists on both sides with identical
-    /// content: record the baseline without transferring anything. Without this,
+    /// First sync of a file that exists on both sides at the same size, with a
+    /// digest on Drive: record the baseline without transferring anything if
+    /// the local file hashes the same, else keep a conflict copy. Without this,
     /// a folder synced for the first time cuts a `(sync-conflict)` copy of every
     /// pre-existing file, because a missing baseline makes both sides read as
-    /// "changed" (see the mass first-sync conflict storm in docs/BUGS.md).
+    /// "changed" (see the mass first-sync conflict storm in docs/BUGS.md). Size
+    /// alone is not enough: a second machine joining the folder would read a
+    /// different file of the same size as in step (B248).
     AdoptBaseline,
 }
 
@@ -223,8 +516,13 @@ pub(super) fn plan_file(
         // left the file the same length, so it was never uploaded.
         baseline.is_none_or(|base| !LocalSig::from(item).same_content(&LocalSig::from(base)))
     });
+    // Another client's new revision shows in its id even when the link's
+    // modification time and the size come out the same.
     let remote_changed = remote.is_some_and(|item| {
-        baseline.is_none_or(|base| remote_sig(base) != Some((item.mtime, item.size)))
+        baseline.is_none_or(|base| {
+            remote_sig(base) != Some((item.mtime, item.size))
+                || revision_moved(Some(base), item.revision.as_deref())
+        })
     });
 
     match (local, remote) {
@@ -234,10 +532,13 @@ pub(super) fn plan_file(
             (false, true) => FilePlan::Download,
             // With a baseline, both-changed is a genuine concurrent edit and must
             // be preserved as a conflict. Without one, "both changed" only means
-            // this is the first sync and there was nothing to compare to: adopt
-            // the baseline when the sizes already match rather than conflict-copy
-            // an already-identical file. Divergent sizes stay a real conflict.
-            (true, true) if baseline.is_none() && l.size == r.size => FilePlan::AdoptBaseline,
+            // this is the first sync and there was nothing to compare to: when the
+            // sizes match and Drive has a digest to compare against, the apply
+            // step hashes the local file before adopting it. Divergent sizes, or
+            // no digest, stay a real conflict: a missing digest proves nothing.
+            (true, true) if baseline.is_none() && l.size == r.size && r.sha1.is_some() => {
+                FilePlan::AdoptBaseline
+            }
             (true, true) => FilePlan::Conflict,
         },
         (Some(_), None) if baseline.is_none() || local_changed => FilePlan::UploadNew,
@@ -269,6 +570,8 @@ mod file_plan_tests {
             is_dir: false,
             mtime,
             size,
+            revision: None,
+            sha1: None,
         }
     }
 
@@ -286,6 +589,7 @@ mod file_plan_tests {
             local_size,
             remote_rev: Some(remote_mtime.to_string()),
             remote_hash: Some(remote_size.to_string()),
+            remote_revision_id: None,
         }
     }
 
@@ -407,12 +711,28 @@ mod file_plan_tests {
     fn first_sync_of_an_identical_file_adopts_the_baseline_not_a_conflict() {
         // No baseline yet (first sync). Same size on both sides is a pre-existing
         // identical file, not a concurrent edit: adopt it rather than cut a
-        // conflict copy of every file in the folder.
+        // conflict copy of every file in the folder. The apply step still
+        // hashes the local file before it records anything.
+        let local = local(10, 40);
+        let remote = RemoteItem {
+            sha1: Some("da39a3ee".into()),
+            ..remote(30, 40)
+        };
+        assert_eq!(
+            plan_file(Some(&local), Some(&remote), None),
+            FilePlan::AdoptBaseline
+        );
+    }
+
+    /// A file on Drive without a digest cannot be compared without a download,
+    /// and the same size is not the same content (B248).
+    #[test]
+    fn first_sync_without_a_remote_digest_is_a_conflict() {
         let local = local(10, 40);
         let remote = remote(30, 40);
         assert_eq!(
             plan_file(Some(&local), Some(&remote), None),
-            FilePlan::AdoptBaseline
+            FilePlan::Conflict
         );
     }
 
@@ -428,6 +748,73 @@ mod file_plan_tests {
         );
     }
 
+    /// Another computer's new revision can leave the modification time and
+    /// the size as they were. The revision id still tells it apart (B249).
+    #[test]
+    fn a_new_remote_revision_is_a_change_even_at_the_same_mtime_and_size() {
+        let mut base = baseline(10, 20, 30, 40);
+        base.remote_revision_id = Some("r1".into());
+        let unedited = local(10, 20);
+        let same = RemoteItem {
+            revision: Some("r1".into()),
+            ..remote(30, 40)
+        };
+        let newer = RemoteItem {
+            revision: Some("r2".into()),
+            ..remote(30, 40)
+        };
+        assert_eq!(
+            plan_file(Some(&unedited), Some(&same), Some(&base)),
+            FilePlan::Unchanged
+        );
+        assert_eq!(
+            plan_file(Some(&unedited), Some(&newer), Some(&base)),
+            FilePlan::Download
+        );
+        let edited = local(11, 20);
+        assert_eq!(
+            plan_file(Some(&edited), Some(&newer), Some(&base)),
+            FilePlan::Conflict
+        );
+
+        // A row from before schema 44 has no id to compare, and a node read
+        // without one says nothing: both fall back to the signature.
+        let old = baseline(10, 20, 30, 40);
+        assert_eq!(
+            plan_file(Some(&unedited), Some(&newer), Some(&old)),
+            FilePlan::Unchanged
+        );
+        assert_eq!(
+            plan_file(Some(&unedited), Some(&remote(30, 40)), Some(&base)),
+            FilePlan::Unchanged
+        );
+    }
+
+    /// The walk reuses the recorded size only while the revision is the one
+    /// the baseline holds.
+    #[test]
+    fn a_moved_revision_makes_the_walk_read_the_size_again() {
+        let mut base = baseline(10, 20, 30, 40);
+        base.remote_revision_id = Some("r1".into());
+        let rows = HashMap::from([("file".to_string(), base)]);
+        assert_eq!(
+            unchanged_remote_size(&rows, "file", 30, Some("r1")),
+            Some(40)
+        );
+        assert_eq!(unchanged_remote_size(&rows, "file", 30, None), Some(40));
+        assert_eq!(unchanged_remote_size(&rows, "file", 30, Some("r2")), None);
+        assert_eq!(unchanged_remote_size(&rows, "file", 31, Some("r1")), None);
+    }
+
+    /// A row without a revision id reuses its size only while Drive gives no
+    /// id either (B254).
+    #[test]
+    fn a_row_without_a_revision_makes_the_walk_read_the_size_again() {
+        let rows = HashMap::from([("file".to_string(), baseline(10, 20, 30, 40))]);
+        assert_eq!(unchanged_remote_size(&rows, "file", 30, Some("r1")), None);
+        assert_eq!(unchanged_remote_size(&rows, "file", 30, None), Some(40));
+    }
+
     #[test]
     fn a_missing_remote_signature_is_treated_as_changed() {
         let local = local(10, 20);
@@ -440,4 +827,153 @@ mod file_plan_tests {
             FilePlan::Download
         );
     }
+
+    fn uid(id: &str) -> NodeUid {
+        NodeUid::new(VolumeId::from("v"), LinkId::from(id))
+    }
+
+    fn folder() -> RemoteItem {
+        RemoteItem {
+            is_dir: true,
+            mtime: 0,
+            size: 0,
+            ..remote(0, 0)
+        }
+    }
+
+    /// An empty or failed remote listing must not read as "Drive deleted
+    /// everything" and delete the local copies.
+    #[test]
+    fn the_remote_wipe_guard_blocks_a_total_disappearance() {
+        let base = HashMap::from([("a".to_string(), ()), ("b".to_string(), ())]);
+        let none: HashMap<String, RemoteItem> = HashMap::new();
+        assert!(guard_remote_wipe(&base, &none).is_err());
+        let one = HashMap::from([("b".to_string(), remote(1, 1))]);
+        assert!(guard_remote_wipe(&base, &one).is_ok());
+        let empty: HashMap<String, ()> = HashMap::new();
+        assert!(guard_remote_wipe(&empty, &none).is_ok());
+    }
+
+    /// One path left of a large folder no longer clears either guard: most
+    /// of it gone at once is a lost tree, not a cleanup (B270).
+    #[test]
+    fn one_survivor_of_a_large_folder_does_not_clear_the_wipe_guards() {
+        let base: HashMap<String, ()> = (0..40).map(|n| (format!("f{n}.txt"), ())).collect();
+        let survivors = |n: usize| -> HashMap<String, ()> {
+            (0..n).map(|n| (format!("f{n}.txt"), ())).collect()
+        };
+        assert!(guard_local_wipe(&base, &survivors(1)).is_err());
+        assert!(guard_remote_wipe(&base, &survivors(1)).is_err());
+        // 36 of 40 gone is nine tenths: still refused.
+        assert!(guard_local_wipe(&base, &survivors(4)).is_err());
+        // 35 of 40 gone is under nine tenths: a pass may delete that much.
+        assert!(guard_local_wipe(&base, &survivors(5)).is_ok());
+        assert!(guard_remote_wipe(&base, &survivors(5)).is_ok());
+        let reason = guard_local_wipe(&base, &survivors(1)).unwrap_err();
+        assert!(reason.starts_with("39 of the 40 synced paths"), "{reason}");
+    }
+
+    /// A small folder still loses most of its files to an ordinary cleanup, so
+    /// only a total loss stops it.
+    #[test]
+    fn a_small_folder_trips_the_wipe_guards_only_when_everything_is_gone() {
+        let base: HashMap<String, ()> = (0..19).map(|n| (format!("f{n}.txt"), ())).collect();
+        let one: HashMap<String, ()> = [("f0.txt".to_string(), ())].into_iter().collect();
+        assert!(guard_local_wipe(&base, &one).is_ok());
+        assert!(guard_remote_wipe(&base, &one).is_ok());
+        let none: HashMap<String, ()> = HashMap::new();
+        assert!(guard_local_wipe(&base, &none).is_err());
+    }
+
+    /// A node that failed to decrypt has no name, so everything a short
+    /// listing did not return is left out, and nothing else.
+    #[test]
+    fn a_short_remote_listing_hides_what_it_did_not_return() {
+        let remote = HashMap::from([
+            ("docs".to_string(), folder()),
+            ("docs/a.txt".to_string(), remote(1, 1)),
+            ("pics".to_string(), folder()),
+        ]);
+        let dirs = HashMap::from([
+            (String::new(), uid("root")),
+            ("docs".to_string(), uid("docs")),
+            ("pics".to_string(), uid("pics")),
+        ]);
+        let mut gaps = RemoteGaps::default();
+        assert!(!gaps.hides("docs/b.txt", &remote, &dirs));
+        gaps.short_listing("docs");
+        // Returned paths stand; unreturned ones under the short folder hide,
+        // and so does anything under a subfolder it failed to return.
+        assert!(!gaps.hides("docs/a.txt", &remote, &dirs));
+        assert!(gaps.hides("docs/b.txt", &remote, &dirs));
+        assert!(gaps.hides("docs/sub/deep.txt", &remote, &dirs));
+        // A complete sibling listing still reads deletions as deletions.
+        assert!(!gaps.hides("pics/gone.jpg", &remote, &dirs));
+        assert!(!gaps.hides("top.txt", &remote, &dirs));
+        gaps.short_listing("");
+        assert!(gaps.hides("top.txt", &remote, &dirs));
+    }
+
+    /// A folder whose listing failed was walked no further: nothing under it
+    /// reads as deleted on Drive, and a sibling that listed still does
+    /// (`docs/BUGS.md` B271).
+    #[test]
+    fn a_folder_that_failed_to_list_hides_everything_under_it() {
+        let remote = HashMap::from([
+            ("docs".to_string(), folder()),
+            ("pics".to_string(), folder()),
+        ]);
+        let dirs = HashMap::from([
+            (String::new(), uid("root")),
+            ("docs".to_string(), uid("docs")),
+            ("pics".to_string(), uid("pics")),
+        ]);
+        let mut gaps = RemoteGaps::default();
+        gaps.unlisted("docs");
+        assert!(gaps.hides("docs/a.txt", &remote, &dirs));
+        assert!(gaps.hides("docs/sub/deep.txt", &remote, &dirs));
+        assert!(!gaps.hides("docs", &remote, &dirs));
+        assert!(!gaps.hides("pics/gone.jpg", &remote, &dirs));
+        assert_eq!(
+            gaps.report(),
+            ["docs (could not be listed on Proton Drive; tried again next pass)"]
+        );
+    }
+
+    #[test]
+    fn a_file_whose_size_could_not_be_read_is_hidden() {
+        let remote: HashMap<String, RemoteItem> = HashMap::new();
+        let dirs = HashMap::from([(String::new(), uid("root"))]);
+        let mut gaps = RemoteGaps::default();
+        gaps.unread("a.txt".to_string());
+        assert!(gaps.hides("a.txt", &remote, &dirs));
+        assert!(!gaps.hides("b.txt", &remote, &dirs));
+        assert_eq!(gaps.report(), ["a.txt (cannot be read on Proton Drive)"]);
+    }
+
+    /// A folder deleted here holds another device's new work on Drive, so
+    /// trashing it would lose that work.
+    #[test]
+    fn a_remote_folder_with_new_or_changed_files_is_not_trashed() {
+        let mut base = HashMap::from([
+            ("x".to_string(), baseline(0, 0, 0, 0)),
+            ("x/old.txt".to_string(), baseline(1, 1, 5, 6)),
+        ]);
+        let mut remote_tree = HashMap::from([
+            ("x".to_string(), folder()),
+            ("x/old.txt".to_string(), remote(5, 6)),
+            ("xy/new.txt".to_string(), remote(1, 1)),
+        ]);
+        // Unchanged under x; a name-prefixed sibling does not count.
+        assert_eq!(remote_subtree_changed("x", &remote_tree, &base), None);
+
+        remote_tree.insert("x/old.txt".to_string(), remote(9, 6));
+        assert!(remote_subtree_changed("x", &remote_tree, &base).is_some());
+
+        remote_tree.insert("x/old.txt".to_string(), remote(5, 6));
+        remote_tree.insert("x/sub".to_string(), folder());
+        assert!(remote_subtree_changed("x", &remote_tree, &base).is_some());
+        base.insert("x/sub".to_string(), baseline(0, 0, 0, 0));
+        assert_eq!(remote_subtree_changed("x", &remote_tree, &base), None);
+    }
 }

crates/pdfs-fuse/src/systemd.rs

@@ -64,16 +64,44 @@ fn send_abstract(socket: &UnixDatagram, name: &str, message: &str) -> bool {
 /// so `systemctl --user start` returns when the mount actually works rather than
 /// when the process exists.
 pub(crate) fn ready() {
-    if notify("READY=1\n") {
+    if notify("READY=1\nSTATUS=Mounted\n") {
         debug!("notified systemd: ready");
     }
 }
 
+/// Set the one-line status `systemctl --user status` shows for the unit, such
+/// as why the mount keeps failing (`docs/BUGS.md` B263).
+pub fn status(text: &str) {
+    // A newline would end the `STATUS=` line and start another variable.
+    let line = text.replace('\n', " ");
+    notify(&format!("STATUS={line}\n"));
+}
+
 /// Tell the manager the daemon is still healthy.
 pub(crate) fn watchdog_ping() {
     let _ = notify("WATCHDOG=1\n");
 }
 
+/// Sleep for `duration`, pinging the watchdog on the way.
+///
+/// For the stretches where the daemon is alive but has no mount, and so no
+/// supervisor: waiting for a login, or backing off after a failed mount. The
+/// manager arms the watchdog when the process starts, so without these pings a
+/// daemon that is merely retrying is aborted after `WatchdogSec` and leaves a
+/// coredump instead of the error it was logging. Never use this while mounted:
+/// there the ping must prove the control socket answers.
+pub fn idle_sleep(duration: Duration) {
+    const CHUNK: Duration = Duration::from_secs(10);
+    let mut left = duration;
+    watchdog_ping();
+    while !left.is_zero() {
+        let step = left.min(CHUNK);
+        std::thread::sleep(step);
+        left -= step;
+        watchdog_ping();
+    }
+}
+
 /// Tell the manager the daemon is stopping, so a slow teardown is not mistaken
 /// for a hang by the watchdog it is racing.
 pub(crate) fn stopping() {

crates/pdfs-fuse/src/takeout.rs

@@ -25,7 +25,7 @@ use std::collections::{BTreeMap, HashMap};
 use std::io::Read;
 use std::path::PathBuf;
 use std::sync::Arc;
-use std::sync::atomic::{AtomicBool, Ordering};
+use std::sync::atomic::{AtomicBool, AtomicU64, Ordering};
 
 use pdfs_core::control::{ActivityKind, ImportSummary, TransferDirection};
 use pdfs_core::takeout::{Bucket, TakeoutPhoto, TakeoutScan, scan_archives};
@@ -36,6 +36,7 @@ use sha1::{Digest, Sha1};
 use tracing::{info, warn};
 
 use super::Core;
+use crate::photos::can_make_thumbnail;
 use crate::transfers::CountingReader;
 
 /// The one import this daemon may be running, and how the last one ended.
@@ -136,6 +137,30 @@ fn read_entry<R>(
 }
 
 impl Core {
+    /// Copy archive entry `entry` into the thumbnail staging folder and return
+    /// its path. The caller removes it.
+    fn stage_takeout_entry(
+        &self,
+        archive: &mut zip::ZipArchive<std::io::BufReader<std::fs::File>>,
+        entry: &str,
+    ) -> CoreResult<PathBuf> {
+        static STAGED: AtomicU64 = AtomicU64::new(0);
+        let path = self.cache.raw_thumbnail_staging_dir().join(format!(
+            "takeout-{}-{}",
+            std::process::id(),
+            STAGED.fetch_add(1, Ordering::Relaxed)
+        ));
+        let copied = read_entry(archive, entry, |reader| {
+            let mut file = std::fs::File::create(&path)?;
+            std::io::copy(reader, &mut file)
+        })?;
+        if let Err(e) = copied {
+            let _ = std::fs::remove_file(&path);
+            return Err(CoreError::internal(format!("copy {entry}: {e}")));
+        }
+        Ok(path)
+    }
+
     /// Import Google Photos Takeout archives. Blocking; run on its own thread.
     ///
     /// `cancel` stops the run at the next photo boundary — an upload already on
@@ -321,18 +346,65 @@ impl Core {
                     capture_time: photo.capture_time,
                     ..Default::default()
                 };
-                let uploaded = read_entry(&mut archive, &photo.entry, |reader| {
-                    let counting = CountingReader::new(reader, &guard);
-                    self.rt.block_on(photos.upload_photo_from(
-                        &photo.name,
-                        &photo.media_type,
-                        counting,
-                        photo.size as i64,
-                        Vec::new(),
-                        metadata,
-                        false,
-                    ))
-                });
+                // A thumbnail is made from a file, so a photo that can have one
+                // is copied out of the archive first and uploaded from the copy.
+                // Without one, Proton's apps show a blank tile until they make
+                // their own.
+                let staged = can_make_thumbnail(&photo.name, photo.size)
+                    .then(|| self.stage_takeout_entry(&mut archive, &photo.entry))
+                    .and_then(|staged| {
+                        staged
+                            .inspect_err(|e| {
+                                warn!(name = photo.name, error = %e,
+                                      "copying a takeout photo out failed; uploading it without a thumbnail")
+                            })
+                            .ok()
+                    });
+                let uploaded = match &staged {
+                    Some(path) => {
+                        let thumbnails = self.upload_thumbnails(path, &photo.name);
+                        // No sidecar and no date in the name: the photo's own
+                        // EXIF, before Drive files it under today.
+                        let metadata = PhotoUploadMetadata {
+                            capture_time: metadata
+                                .capture_time
+                                .or_else(|| pdfs_core::exiftime::capture_time_of(path)),
+                            ..metadata
+                        };
+                        std::fs::File::open(path)
+                            .map_err(|e| {
+                                CoreError::internal(format!("open {}: {e}", path.display()))
+                            })
+                            .map(|file| {
+                                let counting =
+                                    CountingReader::new(std::io::BufReader::new(file), &guard);
+                                self.rt.block_on(photos.upload_photo_from(
+                                    &photo.name,
+                                    &photo.media_type,
+                                    counting,
+                                    photo.size as i64,
+                                    thumbnails,
+                                    metadata,
+                                    false,
+                                ))
+                            })
+                    }
+                    None => read_entry(&mut archive, &photo.entry, |reader| {
+                        let counting = CountingReader::new(reader, &guard);
+                        self.rt.block_on(photos.upload_photo_from(
+                            &photo.name,
+                            &photo.media_type,
+                            counting,
+                            photo.size as i64,
+                            Vec::new(),
+                            metadata,
+                            false,
+                        ))
+                    }),
+                };
+                if let Some(path) = staged {
+                    let _ = std::fs::remove_file(path);
+                }
                 drop(guard);
                 job.step();
 
@@ -480,7 +552,15 @@ impl Core {
                 let mut state = IMPORT.lock();
                 state.running = false;
                 state.cancel = None;
-                state.last = outcome.as_ref().ok().cloned();
+                // A failed run is reported too: without it, `--wait` read
+                // "no import has run" and exited as if all was well.
+                state.last = Some(match &outcome {
+                    Ok(summary) => summary.clone(),
+                    Err(e) => ImportSummary {
+                        error: Some(e.to_string()),
+                        ..Default::default()
+                    },
+                });
             }
             match outcome {
                 Ok(summary) => {
@@ -545,7 +625,7 @@ pub(crate) fn sha1_of(reader: &mut (dyn Read + Send)) -> CoreResult<String> {
     Ok(hex_lower(&hasher.finalize()))
 }
 
-fn hex_lower(bytes: &[u8]) -> String {
+pub(crate) fn hex_lower(bytes: &[u8]) -> String {
     let mut out = String::with_capacity(bytes.len() * 2);
     for byte in bytes {
         out.push_str(&format!("{byte:02x}"));

crates/pdfs-fuse/src/transfers.rs

@@ -46,6 +46,8 @@ struct JobEntry {
     detail: Mutex<String>,
     done: AtomicU64,
     total: AtomicU64,
+    /// Housekeeping that moves nothing; see [`JobItem::background`].
+    background: bool,
 }
 
 /// The set of transfers and jobs currently in flight. Cloned `Arc`-style across
@@ -123,6 +125,11 @@ impl TransferRegistry {
         self.download_limit.set(download);
     }
 
+    /// The upload cap in bytes per second, `0` when there is none.
+    pub fn upload_cap(&self) -> u64 {
+        self.upload_limit.rate.load(Ordering::Relaxed)
+    }
+
     fn limit(&self, direction: TransferDirection) -> &RateLimit {
         match direction {
             TransferDirection::Upload => &self.upload_limit,
@@ -160,12 +167,25 @@ impl TransferRegistry {
     /// that carries its progress and deregisters the job when dropped. The job
     /// starts indeterminate; give it a `total` once one is known.
     pub fn begin_job(self: &Arc<Self>, title: impl Into<String>) -> JobGuard {
+        self.register_job(title.into(), false)
+    }
+
+    /// [`TransferRegistry::begin_job`] for housekeeping the user did not ask
+    /// for and that changes nothing in their files, such as an index rebuild or
+    /// a cache check. It is reported, but front ends don't call the drive busy
+    /// over it.
+    pub fn begin_background_job(self: &Arc<Self>, title: impl Into<String>) -> JobGuard {
+        self.register_job(title.into(), true)
+    }
+
+    fn register_job(self: &Arc<Self>, title: String, background: bool) -> JobGuard {
         let id = self.next.fetch_add(1, Ordering::Relaxed);
         let entry = Arc::new(JobEntry {
-            title: title.into(),
+            title,
             detail: Mutex::new(String::new()),
             done: AtomicU64::new(0),
             total: AtomicU64::new(0),
+            background,
         });
         self.jobs.lock().insert(id, entry.clone());
         JobGuard {
@@ -191,6 +211,7 @@ impl TransferRegistry {
                     detail: e.detail.lock().clone(),
                     done: e.done.load(Ordering::Relaxed),
                     total: e.total.load(Ordering::Relaxed),
+                    background: e.background,
                 }
             })
             .collect()

crates/pdfs-gui/Cargo.toml

@@ -40,4 +40,4 @@ pangocairo = "0.22"
 # Map tiles for the opt-in online map. The same build proton-sdk already pulls in.
 reqwest = { version = "0.13", default-features = false, features = ["rustls", "webpki-roots"] }
 # The system libintl (glibc) rather than a bundled gettext build.
-gettext-rs = { version = "0.7", features = ["gettext-system"] }
+gettext-rs = { version = "0.8", features = ["gettext-system"] }

crates/pdfs-gui/resources/icons/scalable/actions/pdfs-menu-symbolic.svg

@@ -1,5 +0,0 @@
-<svg xmlns="http://www.w3.org/2000/svg" width="16" height="16" viewBox="0 0 16 16">
-  <!-- Main menu: three bars. Bundled because themes such as Papirus draw
-       open-menu-symbolic as three dots, the same as every row's "more" menu. -->
-  <path fill="#222222" d="M 2,2.5 H 14 A 1,1 0 0 1 14,4.5 H 2 A 1,1 0 0 1 2,2.5 Z M 2,7 H 14 A 1,1 0 0 1 14,9 H 2 A 1,1 0 0 1 2,7 Z M 2,11.5 H 14 A 1,1 0 0 1 14,13.5 H 2 A 1,1 0 0 1 2,11.5 Z"/>
-</svg>

crates/pdfs-gui/resources/pdfs.gresource.xml

@@ -14,7 +14,6 @@
     <file preprocess="xml-stripblanks">scalable/actions/pdfs-details-pane-symbolic.svg</file>
     <file preprocess="xml-stripblanks">scalable/actions/pdfs-link-symbolic.svg</file>
     <file preprocess="xml-stripblanks">scalable/actions/pdfs-map-symbolic.svg</file>
-    <file preprocess="xml-stripblanks">scalable/actions/pdfs-menu-symbolic.svg</file>
     <file preprocess="xml-stripblanks">scalable/actions/pdfs-people-symbolic.svg</file>
     <file preprocess="xml-stripblanks">scalable/actions/pdfs-share-symbolic.svg</file>
     <file preprocess="xml-stripblanks">scalable/actions/pdfs-sync-symbolic.svg</file>

crates/pdfs-gui/resources/style.css

@@ -18,7 +18,9 @@
 .sidebar-status image.warning { color: var(--warning-color); }
 .sidebar-status image.error { color: var(--error-color); }
 .sidebar-quota progressbar trough, .sidebar-quota progressbar progress { min-height: 4px; }
-.sidebar-account { padding: 4px 4px 4px 8px; }
+/* The account row is the main menu's button: a row, not a pushbutton, so
+ * the name keeps the text weight. */
+button.sidebar-account { padding: 4px 8px; font-weight: normal; }
 /* A count of what waits on a page, at the end of its sidebar row */
 .sidebar-badge {
   min-width: 10px;
@@ -48,6 +50,9 @@
 .badge-cloud { color: color-mix(in srgb, currentColor 55%, transparent); }
 .badge-issue { color: var(--error-color); }
 .browser-statusbar { background-color: alpha(currentColor, 0.025); }
+/* The folder on screen, last in the breadcrumb trail: a flat button's side
+ * padding, so the "›" before it is spaced like the ones between buttons. */
+.crumb-current { padding: 0 10px; }
 scale.browser-status-meter trough { min-width: 104px; min-height: 6px; }
 .bulk-bar { padding: 6px 8px; border-radius: 12px; background: color-mix(in srgb, var(--accent-bg-color) 12%, transparent); }
 .dropzone { border: 2px dashed alpha(currentColor, 0.25); border-radius: 16px; padding: 28px 18px; transition: background 160ms ease, border-color 160ms ease; }

crates/pdfs-gui/src/activation.rs

@@ -10,9 +10,14 @@
 //! `dead_code` allowances below are for — not code nobody uses.
 
 use std::path::{Path, PathBuf};
+use std::time::Duration;
 
 use pdfs_core::control::{PhotoKind, SearchHit};
 
+/// How long a `stat` of the mount may take before the file counts as not
+/// there. A frozen mount never answers, and every caller has a fallback.
+const STAT_TIMEOUT: Duration = Duration::from_secs(2);
+
 #[derive(Debug, Clone, Copy, PartialEq, Eq)]
 pub(crate) enum DriveActivation {
     Folder,
@@ -55,18 +60,32 @@ pub(crate) fn mounted_target(mountpoint: &Path, hit: &SearchHit) -> Option<PathB
     present(mounted_or_relative(mountpoint, hit))
 }
 
-/// [`mounted_target`] for callers holding a mountpoint-relative path rather
-/// than a search hit — the browser's listing entries, which are by definition
-/// paths in the primary mount's tree.
-#[allow(dead_code)] // browser only
-pub(crate) fn mounted_target_rel(mountpoint: &Path, relative_path: &str) -> Option<PathBuf> {
-    present(mounted_path(mountpoint, relative_path))
-}
-
 fn present(path: PathBuf) -> Option<PathBuf> {
     path.symlink_metadata().is_ok().then_some(path)
 }
 
+/// Whether anything is at `path`, asked on a thread of its own and given up
+/// on after [`STAT_TIMEOUT`]. `None` means "not there" or "no answer".
+///
+/// For the GTK binaries, whose main thread must not `stat` the mount: a
+/// mount that hangs hung the whole window with it. The thread of a `stat`
+/// that never returns is left behind; there is no way to cancel one.
+#[allow(dead_code)] // GTK binaries only
+pub(crate) async fn present_within(path: PathBuf) -> Option<PathBuf> {
+    let (tx, rx) = async_channel::bounded(1);
+    std::thread::spawn(move || {
+        let _ = tx.send_blocking(present(path));
+    });
+    match gtk4::glib::future_with_timeout(STAT_TIMEOUT, rx.recv()).await {
+        Ok(Ok(target)) => target,
+        Ok(Err(_)) => None,
+        Err(_) => {
+            tracing::warn!("the mount did not answer in time");
+            None
+        }
+    }
+}
+
 /// The mount path for a hit, whether or not anything is there — for callers
 /// that have no fallback (a folder cannot be materialised) or already know the
 /// entry came from a mount listing.

crates/pdfs-gui/src/app/main.rs

@@ -10,6 +10,7 @@ pub(crate) mod pages;
 pub(crate) mod reload;
 #[path = "../theme.rs"]
 pub(crate) mod theme;
+pub(crate) mod update;
 pub(crate) mod widgets;
 
 use compat::*;
@@ -33,7 +34,9 @@ use pages::trash::*;
 use pages::verify::*;
 use reload::{LoadTicket, Loader, replace_items};
 use theme::{load_resources, proton_theme_active, set_proton_theme};
+use update::*;
 use widgets::compat::*;
+use widgets::crumb::*;
 use widgets::details::*;
 use widgets::file_list::*;
 use widgets::menu::*;
@@ -68,15 +71,15 @@ use gtk4::glib::BoxedAnyObject;
 
 use pdfs_core::auth;
 
-use pdfs_core::config::{AppDirs, FileSort, FilesView};
+use pdfs_core::config::{AppDirs, FileSort, FilesView, WindowState};
 
 use pdfs_core::control::{
     ActivityEntry, ActivityKind, AlbumInfo, BookmarkInfo, ConflictInfo, ConflictKeep, DeviceInfo,
-    DirEntry, ErrorKind, ImportSummary, InvitationInfo, JobItem, MappingProgress, PendingOpInfo,
-    PhotoItem, PhotoKind, PhotoMonth, PlaceInfo, PublicLinkInfo, RefreshScope, Request, Response,
-    RestorableFolder, RestoreItem, RevisionInfo, SearchHit, ShareEntry, ShareEntryKind, SharedItem,
-    SyncFolderInfo, SyncIssue, SyncPhase, SyncProgress, ThumbnailBuildStatus, Topic,
-    TransferDirection, TransferItem, send,
+    DirEntry, ErrorKind, ImportSummary, InvitationInfo, JobItem, LinkChange, MappingProgress,
+    PendingOpInfo, PhotoItem, PhotoKind, PhotoMonth, PlaceInfo, PublicLinkInfo, RefreshScope,
+    Request, Response, RestorableFolder, RestoreItem, RevisionInfo, SearchHit, ShareEntry,
+    ShareEntryKind, SharedItem, SyncFolderInfo, SyncIssue, SyncPhase, SyncProgress,
+    ThumbnailBuildStatus, Topic, TransferDirection, TransferItem, send,
 };
 
 use pdfs_core::mounts::{MountAccess, MountKind, MountMode, MountSpec};
@@ -119,6 +122,12 @@ struct Ui {
     /// keyring (a DBus round-trip). Populated at startup and updated only on
     /// login / logout. `None` = signed out.
     session: RefCell<Option<auth::StoredSession>>,
+    /// Whether this run already asked for the mailbox password of a locked
+    /// account, so a refresh never re-opens a dialog the user cancelled.
+    unlock_offered: Cell<bool>,
+    /// The `since` of the run of mount failures whose "folder isn't empty"
+    /// dialog this run already showed, so a page reload never shows it again.
+    not_empty_offered: Cell<i64>,
     /// Whether the last refresh saw a live mount daemon. Gates the unpin buttons
     /// (which need the daemon to evict + re-hydrate) and every mutating action.
     mounted: RefCell<bool>,
@@ -126,8 +135,12 @@ struct Ui {
     /// the page stack; [`sync_sidebar`] mirrors navigation that starts elsewhere.
     sidebar: gtk4::ListBox,
     /// The sidebar/content split. Collapsed while signed out, so the login page
-    /// owns the whole window and no destination is reachable without a session.
+    /// owns the whole window and no destination is reachable without a session,
+    /// and while the window is [`narrow`](Self::narrow).
     nav: adw::NavigationSplitView,
+    /// The window is too narrow for the sidebar beside a page, so the two take
+    /// turns. Set by the narrow breakpoint; [`refresh`] reads it.
+    narrow: Cell<bool>,
     /// Shared thumbnails for ordinary image files outside the Photos gallery.
     /// One cache and request queue serves Files, search, Shared and Trash, so
     /// the same image is downloaded and decoded only once.
@@ -147,6 +160,7 @@ struct Ui {
     pub(crate) locations: LocationsState,
     pub(crate) activity: ActivityState,
     pub(crate) takeout: TakeoutState,
+    pub(crate) update: UpdateState,
 }
 
 impl Ui {
@@ -199,12 +213,20 @@ impl Ui {
 }
 
 fn main() -> glib::ExitCode {
-    tracing_subscriber::fmt()
-        .with_env_filter(
-            tracing_subscriber::EnvFilter::try_from_default_env().unwrap_or_else(|_| "info".into()),
-        )
-        .init();
+    let verify = std::env::args().nth(1).as_deref() == Some(VERIFY_ARG);
+    let logs = tracing_subscriber::fmt().with_env_filter(
+        tracing_subscriber::EnvFilter::try_from_default_env().unwrap_or_else(|_| "info".into()),
+    );
+    // The verification window's stdout carries its token back to the app.
+    if verify {
+        logs.with_writer(std::io::stderr).init();
+    } else {
+        logs.init();
+    }
     i18n::init();
+    if verify {
+        return run_verification_window();
+    }
 
     // The tray launches the app with arguments ("--page locations",
     // "--confirm-stop"), which a running instance must receive too.
@@ -285,7 +307,10 @@ fn present_window(app: &adw::Application) {
 /// Spawn the tray icon process in the background.
 pub(crate) fn spawn_tray() {
     match Command::new("pdfs-tray").spawn() {
-        Ok(_) => tracing::info!("spawned `pdfs-tray`"),
+        Ok(child) => {
+            tracing::info!("spawned `pdfs-tray`");
+            pdfs_core::opener::reap(child);
+        }
         Err(e) => tracing::error!("failed to spawn `pdfs-tray`: {e}"),
     }
 }
@@ -300,8 +325,15 @@ fn build_window(app: &adw::Application) {
             return;
         }
     };
+    // On a fresh install the daemon has not run yet to make these, and the
+    // Takeout page keeps its staged archives in the state dir (B194).
+    if let Err(e) = dirs.ensure() {
+        tracing::warn!("cannot create the app's directories: {e}");
+    }
 
-    let stack = adw::ViewStack::new();
+    // Not homogeneous: each page sets the window's minimum width only while it
+    // is shown, so the widest page does not hold every other one wide.
+    let stack = adw::ViewStack::builder().hhomogeneous(false).build();
     let (login_page, login_widgets) = build_login_page();
     let main_widgets = build_main_page();
     let (browser_page, browser_widgets) = build_browser_page();
@@ -319,8 +351,12 @@ fn build_window(app: &adw::Application) {
     login_frame.add_top_bar(&{
         let header = adw::HeaderBar::new();
         header.set_show_title(false);
+        // The split is collapsed while signed out; going "back" would only
+        // uncover a sidebar with nowhere to go.
+        header.set_show_back_button(false);
         header
     });
+    login_frame.add_top_bar(&login_widgets.keyring_banner);
     login_frame.set_content(Some(&login_page));
     stack.add_named(&login_frame, Some("login"));
     stack.add_named(&browser_page, Some("browser"));
@@ -335,7 +371,8 @@ fn build_window(app: &adw::Application) {
     // Sidebar: the signed-in destinations. Selecting a row swaps the page stack;
     // `sync_sidebar` pushes the other way when navigation happens elsewhere (e.g.
     // login lands on Files).
-    let (sidebar_page, sidebar_list) = build_sidebar(&main_widgets.footer);
+    let update = UpdateState::new();
+    let (sidebar_page, sidebar_list) = build_sidebar(&main_widgets.footer, &update.banner);
 
     // Every page brings its own header bar (see `page_frame`), so the content
     // side is the bare stack.
@@ -348,6 +385,8 @@ fn build_window(app: &adw::Application) {
         .content(&content_page)
         .min_sidebar_width(200.0)
         .max_sidebar_width(240.0)
+        // A narrow window opens on the page, not the sidebar.
+        .show_content(true)
         .build();
 
     // Toasts float over everything, so a report from a background action reaches
@@ -355,16 +394,23 @@ fn build_window(app: &adw::Application) {
     let toasts = adw::ToastOverlay::new();
     toasts.set_child(Some(&split));
 
+    let (startup_session, keyring_error) = match read_session() {
+        Ok(session) => (session, None),
+        Err(e) => (None, Some(e)),
+    };
     let ui = Rc::new(Ui {
         dirs,
         stack: stack.clone(),
         toasts: toasts.clone(),
         busy: Cell::new(0),
         opening: RefCell::new(HashSet::new()),
-        session: RefCell::new(auth::load().ok()),
+        session: RefCell::new(startup_session),
+        unlock_offered: Cell::new(false),
+        not_empty_offered: Cell::new(0),
         mounted: RefCell::new(false),
         sidebar: sidebar_list.clone(),
         nav: split.clone(),
+        narrow: Cell::new(false),
         file_thumbs: FileThumbnailState::new(),
         login: login_widgets,
         status: StatusState {
@@ -394,6 +440,7 @@ fn build_window(app: &adw::Application) {
             theme_row: main_widgets.theme_row.clone(),
             online_map_row: main_widgets.online_map_row.clone(),
             tray_row: main_widgets.tray_row.clone(),
+            update_row: main_widgets.update_row.clone(),
             language_row: main_widgets.language_row.clone(),
             settings_suppress: Cell::new(false),
             budget_source: RefCell::new(None),
@@ -520,6 +567,7 @@ fn build_window(app: &adw::Application) {
             reload_pending: Cell::new(false),
             loading: Cell::new(false),
             has_more: Cell::new(false),
+            library: Cell::new(true),
             page_waiters: RefCell::new(Vec::new()),
             width: Cell::new(0),
             photo_tex: RefCell::new(HashMap::new()),
@@ -561,6 +609,8 @@ fn build_window(app: &adw::Application) {
                 detail: locations_widgets.card_detail.clone(),
                 pause: locations_widgets.pause.clone(),
                 paused: Cell::new(false),
+                sign_in: locations_widgets.card_sign_in.clone(),
+                restart: locations_widgets.card_restart.clone(),
             },
             queue: QueueState {
                 group: locations_widgets.queue_group.clone(),
@@ -613,8 +663,12 @@ fn build_window(app: &adw::Application) {
             running: Cell::new(false),
             dry_run: Cell::new(false),
         },
+        update,
     });
     wire_login(&ui);
+    if let Some(e) = keyring_error {
+        keyring_unreadable(&ui, &e);
+    }
     let ui_status = ui.clone();
     main_widgets
         .status_button
@@ -656,6 +710,7 @@ fn build_window(app: &adw::Application) {
     wire_activity(&ui, &activity_widgets);
     wire_takeout(&ui, &takeout_widgets);
     wire_retry(&ui);
+    wire_update(&ui);
 
     // Lazily load the Files / Photos pages the first time they're shown, so the
     // network round-trip only happens on demand rather than on every refresh.
@@ -692,13 +747,18 @@ fn build_window(app: &adw::Application) {
         }
     });
 
+    let saved = ui.dirs.load_config().window.usable();
     let window = adw::ApplicationWindow::builder()
         .application(app)
         .title("Proton Drive")
-        .default_width(980)
-        .default_height(680)
+        .default_width(saved.width)
+        .default_height(saved.height)
+        .maximized(saved.maximized)
+        .width_request(WindowState::MIN_WIDTH)
+        .height_request(WindowState::MIN_HEIGHT)
         .content(&toasts)
         .build();
+    remember_window_state(&ui, app, &window);
     // A wide window docks the details pane beside the files instead of laying it
     // over them.
     let wide = adw::Breakpoint::new(
@@ -706,6 +766,18 @@ fn build_window(app: &adw::Application) {
     );
     wide.add_setter(&ui.browser.split, "collapsed", Some(&false.to_value()));
     window.add_breakpoint(wide);
+    // A narrow window shows the sidebar and the page in turn, so every header
+    // bar keeps room for the window buttons. Signals rather than a setter:
+    // `refresh` decides the collapse while signed out, and would undo one.
+    let narrow = adw::Breakpoint::new(
+        adw::BreakpointCondition::parse("max-width: 760sp").expect("static breakpoint"),
+    );
+    narrow.add_setter(&ui.browser.search, "width-chars", Some(&8.to_value()));
+    let ui_narrow = ui.clone();
+    narrow.connect_apply(move |_| set_narrow(&ui_narrow, true));
+    let ui_wide = ui.clone();
+    narrow.connect_unapply(move |_| set_narrow(&ui_wide, false));
+    window.add_breakpoint(narrow);
     install_shortcuts(&ui, &window);
     install_window_actions(&ui, &window);
     install_launch_actions(&ui, app, &window);
@@ -719,6 +791,51 @@ fn build_window(app: &adw::Application) {
     window.present();
 }
 
+/// Follow the narrow breakpoint. While signed out the login page keeps the
+/// split collapsed whatever the width.
+fn set_narrow(ui: &Ui, narrow: bool) {
+    ui.narrow.set(narrow);
+    if ui.session.borrow().is_some() {
+        ui.nav.set_collapsed(narrow);
+    }
+}
+
+/// Save the window's size when it closes, and when the app quits with the
+/// window still open (Ctrl+Q, the tray's Quit), which never asks it to close.
+fn remember_window_state(ui: &Rc<Ui>, app: &adw::Application, window: &adw::ApplicationWindow) {
+    let ui_close = ui.clone();
+    window.connect_close_request(move |window| {
+        save_window_state(&ui_close, window);
+        glib::Propagation::Proceed
+    });
+    let ui_quit = ui.clone();
+    let window_quit = window.downgrade();
+    app.connect_shutdown(move |_| {
+        if let Some(window) = window_quit.upgrade() {
+            save_window_state(&ui_quit, &window);
+        }
+    });
+}
+
+/// Write the window's unmaximised size and maximised state to the config, if
+/// either changed. Runs as the window goes away, so a failure is only logged.
+fn save_window_state(ui: &Ui, window: &adw::ApplicationWindow) {
+    let (width, height) = window.default_size();
+    let state = WindowState {
+        width,
+        height,
+        maximized: window.is_maximized(),
+    };
+    let mut config = ui.dirs.load_config();
+    if config.window == state {
+        return;
+    }
+    config.window = state;
+    if let Err(e) = ui.dirs.save_config(&config) {
+        tracing::warn!("cannot save the window size: {e}");
+    }
+}
+
 /// Whether `window` is minimised or otherwise out of sight (another workspace,
 /// fully covered), as far as the compositor tells us.
 fn window_hidden(window: &adw::ApplicationWindow) -> bool {
@@ -765,10 +882,13 @@ const DESTINATIONS: [(&str, &str, &str); 7] = [
 /// Index of the first row in the sidebar's sync section.
 const SIDEBAR_SYNC_SECTION: i32 = 6;
 
-/// The navigation sidebar: the destinations over a footer carrying the sync
-/// status, the account quota and the account menu. Returns the page (for the
+/// The navigation sidebar: the destinations under the update banner and over a
+/// footer carrying the sync status, the account quota and the account menu. Returns the page (for the
 /// split view) and the list (to drive + reflect the current page).
-fn build_sidebar(footer: &gtk4::Box) -> (adw::NavigationPage, gtk4::ListBox) {
+fn build_sidebar(
+    footer: &gtk4::Box,
+    update_banner: &adw::Banner,
+) -> (adw::NavigationPage, gtk4::ListBox) {
     let list = gtk4::ListBox::new();
     list.set_selection_mode(gtk4::SelectionMode::Single);
     list.add_css_class("navigation-sidebar");
@@ -813,7 +933,6 @@ fn build_sidebar(footer: &gtk4::Box) -> (adw::NavigationPage, gtk4::ListBox) {
 
     let header = adw::HeaderBar::new();
     header.set_title_widget(Some(&brand));
-    header.pack_end(&build_primary_menu());
 
     let scroll = gtk4::ScrolledWindow::builder()
         .hscrollbar_policy(gtk4::PolicyType::Never)
@@ -822,6 +941,7 @@ fn build_sidebar(footer: &gtk4::Box) -> (adw::NavigationPage, gtk4::ListBox) {
         .build();
     let toolbar = adw::ToolbarView::new();
     toolbar.add_top_bar(&header);
+    toolbar.add_top_bar(update_banner);
     toolbar.set_content(Some(&scroll));
     toolbar.add_bottom_bar(footer);
 
@@ -847,6 +967,18 @@ fn set_busy_spinners(visible: bool) {
     });
 }
 
+/// `row` in a frame that scrolls sideways once the window is too narrow for it,
+/// so a row of labelled buttons never sets the window's minimum width.
+fn scroll_sideways(row: &impl IsA<gtk4::Widget>) -> gtk4::ScrolledWindow {
+    gtk4::ScrolledWindow::builder()
+        .hscrollbar_policy(gtk4::PolicyType::Automatic)
+        .vscrollbar_policy(gtk4::PolicyType::Never)
+        .propagate_natural_width(true)
+        .propagate_natural_height(true)
+        .child(row)
+        .build()
+}
+
 /// A destination page's frame: its own header bar over the page content, the
 /// way GNOME apps lay a split view out. The title sits in the middle with the
 /// busy spinner beside it; the page packs its actions into the returned header
@@ -910,6 +1042,14 @@ fn wire_sidebar(ui: &Rc<Ui>) {
             ui_row.stack.set_visible_child_name(page);
         }
     });
+    // In a narrow window the sidebar covers the page, so picking a row, even
+    // the selected one, has to bring the page forward.
+    let ui_open = ui.clone();
+    ui.sidebar.connect_row_activated(move |_, _| {
+        if ui_open.nav.is_collapsed() {
+            ui_open.nav.set_show_content(true);
+        }
+    });
 }
 
 /// Re-fetch the visible page from the server, bypassing every layer of cache
@@ -1045,8 +1185,17 @@ pub(crate) fn set_sidebar_badge(ui: &Ui, page: &str, count: u64) {
 /// Show a transient toast. Non-blocking by design: an action's outcome is
 /// reported without stealing focus or forcing a click, so the user can keep
 /// working while a slow upload lands.
+///
+/// A toast's title is Pango markup unless told otherwise. Messages carry file
+/// names and daemon errors, and one with a `&` or `<` in it showed as an empty
+/// toast, so every toast here is plain text.
 fn toast(ui: &Rc<Ui>, message: &str) {
-    ui.toasts.add_toast(adw::Toast::new(message));
+    ui.toasts.add_toast(
+        adw::Toast::builder()
+            .title(message)
+            .use_markup(false)
+            .build(),
+    );
 }
 
 /// Show a toast that offers one follow-up action — an Undo, or a way to the page
@@ -1057,6 +1206,7 @@ fn toast(ui: &Rc<Ui>, message: &str) {
 fn toast_action(ui: &Rc<Ui>, message: &str, label: &str, action: impl Fn(&Rc<Ui>) + 'static) {
     let toast = adw::Toast::builder()
         .title(message)
+        .use_markup(false)
         .button_label(label)
         .timeout(8)
         .build();
@@ -1079,7 +1229,11 @@ fn toast_error(ui: &Rc<Ui>, what: &str, detail: &str) {
         gettext_f("{what}: {detail}", &[("what", what), ("detail", detail)])
     };
     tracing::warn!("{message}");
-    let toast = adw::Toast::builder().title(&message).timeout(6).build();
+    let toast = adw::Toast::builder()
+        .title(&message)
+        .use_markup(false)
+        .timeout(6)
+        .build();
     ui.toasts.add_toast(toast);
 }
 
@@ -1136,25 +1290,7 @@ fn toast_failure(ui: &Rc<Ui>, what: &str, message: &str, kind: ErrorKind) {
     }
 }
 
-/// The sidebar's primary (hamburger) menu: the app-level entries that don't
-/// belong on any one page.
-fn build_primary_menu() -> gtk4::MenuButton {
-    let menu = gio::Menu::new();
-    menu.append(Some(&gettext("Preferences")), Some("win.preferences"));
-    menu.append(Some(&gettext("Keyboard Shortcuts")), Some("win.shortcuts"));
-    menu.append(
-        Some(&gettext("About Proton Drive for Linux")),
-        Some("win.about"),
-    );
-    gtk4::MenuButton::builder()
-        .icon_name("pdfs-menu-symbolic")
-        .tooltip_text(gettext("Main menu"))
-        .primary(true)
-        .menu_model(&menu)
-        .build()
-}
-
-/// Back the primary and account menus' entries with window actions.
+/// Back the main menu's entries with window actions.
 fn install_window_actions(ui: &Rc<Ui>, window: &adw::ApplicationWindow) {
     let preferences = gio::SimpleAction::new("preferences", None);
     let ui_prefs = ui.clone();
@@ -1206,7 +1342,7 @@ fn install_window_actions(ui: &Rc<Ui>, window: &adw::ApplicationWindow) {
         let dialog = adw::AboutDialog::builder()
             .application_name(gettext("Proton Drive for Linux"))
             .application_icon("io.narl.proton-drive-linux")
-            .version(pdfs_core::config::APP_VERSION)
+            .version(env!("CARGO_PKG_VERSION"))
             .developer_name("Nils Pukropp")
             .website("https://proton-drive.narl.io")
             .issue_url("https://github.com/narrrl/proton-drive-linux/issues")
@@ -1291,6 +1427,12 @@ fn install_launch_actions(ui: &Rc<Ui>, app: &adw::Application, window: &adw::App
         if ui_page.session.borrow().is_none() {
             return;
         }
+        // Signed in, but Proton refused the session (the tray's "Sign In
+        // Again…"): the login page, with the rest of the app still reachable.
+        if page == "login" {
+            show_login(&ui_page);
+            return;
+        }
         // Activity lives on as the Sync page's History view.
         if page == "activity" {
             ui_page.locations.views.set_visible_child_name("history");
@@ -1346,8 +1488,8 @@ fn debug_info(ui: &Rc<Ui>) -> String {
     format!(
         "App version: {}\nUser agent: {}\nlibadwaita: {}.{}.{}\nGTK: {}.{}.{}\n\
          Mountpoint: {}\nControl socket: {}\nMount service running: {}\n",
-        pdfs_core::config::APP_VERSION,
-        pdfs_core::config::USER_AGENT,
+        config.resolved_app_version(),
+        config.resolved_user_agent(),
         adw::major_version(),
         adw::minor_version(),
         adw::micro_version(),
@@ -1659,13 +1801,52 @@ pub(crate) fn service_unreachable(
             );
             return;
         }
-        status(
-            &ui,
-            "network-idle-symbolic",
-            &gettext("Connecting…"),
-            &gettext("Waiting for the Proton Drive service to start."),
-            false,
-        );
+        // Running but not answering may be a mount that fails on every try,
+        // which never opens the socket. Its reason is in a file the daemon
+        // keeps for this (B263); "Connecting…" alone looked like a slow start
+        // for as long as it lasted.
+        let state_dir = ui.dirs.state_dir();
+        let failure = gio::spawn_blocking(move || pdfs_core::mountfail::read(&state_dir))
+            .await
+            .ok()
+            .flatten();
+        match failure {
+            Some(failure) if failure.not_empty.is_some() => {
+                let found = failure.not_empty.as_ref().expect("checked above");
+                status(
+                    &ui,
+                    "dialog-warning-symbolic",
+                    &gettext("Can't open your Drive"),
+                    // Translators: {path} is the folder My files is mounted at.
+                    &gettext_f(
+                        "“{path}” already has files in it, and My files would hide them. Proton Drive tries again on its own once the folder is empty. You can also choose another folder for My files in Preferences.",
+                        &[("path", &found.path.display().to_string())],
+                    ),
+                    true,
+                );
+                if ui.not_empty_offered.replace(failure.since) != failure.since {
+                    offer_not_empty(&ui, found);
+                }
+            }
+            Some(failure) => status(
+                &ui,
+                "dialog-warning-symbolic",
+                &gettext("Can't open your Drive"),
+                // Translators: {error} is an error message, in English.
+                &gettext_f(
+                    "The Proton Drive service keeps failing to start and tries again on its own. The last error was: {error}",
+                    &[("error", &failure.error)],
+                ),
+                true,
+            ),
+            None => status(
+                &ui,
+                "network-idle-symbolic",
+                &gettext("Connecting…"),
+                &gettext("Waiting for the Proton Drive service to start."),
+                false,
+            ),
+        }
         glib::timeout_add_local_once(CONNECT_RETRY_INTERVAL, move || {
             if ui.stack.visible_child_name().as_deref() == Some(page) {
                 reload(&ui);
@@ -1674,6 +1855,37 @@ pub(crate) fn service_unreachable(
     });
 }
 
+/// Tell the user the daemon will not mount My files over a folder with files
+/// in it (B277), and offer the two ways out: open the folder to move them, or
+/// choose another one.
+fn offer_not_empty(ui: &Rc<Ui>, found: &pdfs_core::mountpoint::NotEmpty) {
+    let path = found.path.display().to_string();
+    let dialog = adw::AlertDialog::builder()
+        .heading(gettext("Your Proton Drive Folder Isn't Empty"))
+        // Translators: {path} is the folder My files is mounted at; {n} is how
+        // many files and folders are already in it.
+        .body(ngettext_f(
+            "“{path}” already has {n} item in it. My files would hide it, so Proton Drive does not open there. Move the item to another folder, or choose another folder for My files.",
+            "“{path}” already has {n} items in it. My files would hide them, so Proton Drive does not open there. Move the items to another folder, or choose another folder for My files.",
+            found.count as u64,
+            &[("path", &path)],
+        ))
+        .build();
+    dialog.add_response("close", &gettext("Not Now"));
+    dialog.add_response("open", &gettext("Open Folder"));
+    dialog.add_response("choose", &gettext("Choose Another Folder…"));
+    dialog.set_response_appearance("choose", adw::ResponseAppearance::Suggested);
+    dialog.set_default_response(Some("choose"));
+    dialog.set_close_response("close");
+    let ui_response = ui.clone();
+    dialog.connect_response(None, move |_, response| match response {
+        "open" => open_path(&path),
+        "choose" => prompt_mountpoint(&ui_response),
+        _ => {}
+    });
+    dialog.present(ui_window(ui).as_ref());
+}
+
 /// How long a copy button shows its check after copying.
 const COPIED_FEEDBACK: Duration = Duration::from_millis(1500);
 
@@ -1691,9 +1903,12 @@ pub(crate) fn flash_copied(button: &gtk4::Button, icon: &'static str) {
 
 /// Open a local path with the handler the user configured — `xdg-open` unless
 /// `open_with` in `config.json` overrides it for this kind of file.
+///
+/// On a thread of its own: telling a folder from a file is a `stat`, and the
+/// path is often in the mount, which may hang.
 fn open_path(path: &str) {
-    let path = Path::new(path);
-    pdfs_core::opener::open_default(path, path.is_dir());
+    let path = PathBuf::from(path);
+    std::thread::spawn(move || pdfs_core::opener::open_default(&path, path.is_dir()));
 }
 
 /// [`open_path`] for a file the daemon materialised into the content cache,

crates/pdfs-gui/src/app/pages/activity.rs

@@ -378,7 +378,9 @@ pub(crate) fn activity_status(
 ) {
     ui.activity.status.set_icon_name(Some(icon));
     ui.activity.status.set_title(title);
-    ui.activity.status.set_description(Some(description));
+    ui.activity
+        .status
+        .set_description(Some(&gtk4::glib::markup_escape_text(description)));
     ui.activity.retry.set_visible(retry);
     ui.activity.content.set_visible_child_name("status");
 }
@@ -1041,6 +1043,7 @@ pub(crate) fn activity_icon(kind: ActivityKind) -> &'static str {
         ActivityKind::Sync => "pdfs-sync-symbolic",
         ActivityKind::Rename => "document-edit-symbolic",
         ActivityKind::Move => "go-jump-symbolic",
+        ActivityKind::Copy => "edit-copy-symbolic",
         ActivityKind::CreateFolder => "folder-new-symbolic",
         ActivityKind::Trash => "user-trash-symbolic",
         ActivityKind::DeleteForever | ActivityKind::EmptyTrash => "edit-delete-symbolic",

crates/pdfs-gui/src/app/pages/activity_text.rs

@@ -179,6 +179,10 @@ pub(crate) fn activity_title(kind: ActivityKind, ok: bool, name: &str) -> String
         (ActivityKind::Move, true) => gettext_f("Moved {name}", &args),
         // Translators: {name} is a file or folder name.
         (ActivityKind::Move, false) => gettext_f("Couldn't move {name}", &args),
+        // Translators: {name} is a file or folder name.
+        (ActivityKind::Copy, true) => gettext_f("Copied {name}", &args),
+        // Translators: {name} is a file or folder name.
+        (ActivityKind::Copy, false) => gettext_f("Couldn't copy {name}", &args),
         // Translators: {name} is a folder name.
         (ActivityKind::CreateFolder, true) => gettext_f("Created folder {name}", &args),
         // Translators: {name} is a folder name.

crates/pdfs-gui/src/app/pages/albums.rs

@@ -645,7 +645,9 @@ pub(crate) fn close_album(ui: &Rc<Ui>) {
 fn albums_status(ui: &Rc<Ui>, icon: &str, title: &str, description: &str) {
     ui.gallery.albums_status.set_icon_name(Some(icon));
     ui.gallery.albums_status.set_title(title);
-    ui.gallery.albums_status.set_description(Some(description));
+    ui.gallery
+        .albums_status
+        .set_description(Some(&gtk4::glib::markup_escape_text(description)));
     ui.gallery.albums_stack.set_visible_child_name("status");
 }
 

crates/pdfs-gui/src/app/pages/browser.rs

@@ -1,4 +1,4 @@
-use crate::activation::{DriveActivation, drive_activation, mounted_path, mounted_target_rel};
+use crate::activation::{DriveActivation, drive_activation, mounted_path, present_within};
 use crate::*;
 
 pub(crate) struct BrowserState {
@@ -376,7 +376,7 @@ pub(crate) fn build_browser_page() -> (gtk4::Widget, BrowserWidgets) {
     bulk_box.append(&bulk_clear);
     let bulk = gtk4::Revealer::builder()
         .transition_type(gtk4::RevealerTransitionType::SlideDown)
-        .child(&bulk_box)
+        .child(&scroll_sideways(&bulk_box))
         .build();
 
     // The status bar: contextual text (stretch 1), then the icon-size slider.
@@ -500,7 +500,9 @@ pub(crate) fn build_browser_page() -> (gtk4::Widget, BrowserWidgets) {
 pub(crate) fn browser_status(ui: &Rc<Ui>, icon: &str, title: &str, description: &str, retry: bool) {
     ui.browser.status.set_icon_name(Some(icon));
     ui.browser.status.set_title(title);
-    ui.browser.status.set_description(Some(description));
+    ui.browser
+        .status
+        .set_description(Some(&gtk4::glib::markup_escape_text(description)));
     ui.browser.retry.set_visible(retry);
     // Only the empty-folder state offers a way to fill the folder; every other
     // status (loading, offline, error) turns them back off.
@@ -520,9 +522,9 @@ pub(crate) fn clear_selection(ui: &Rc<Ui>) {
 }
 
 /// Reflect the current selection in the bulk bar: how many are selected, and
-/// which bulk actions apply to that mix. Offline state is a file-only notion, so
-/// a folder anywhere in the selection disables the two pin buttons rather than
-/// half-failing once pressed.
+/// which bulk actions apply to that mix. An entry kept offline through a pinned
+/// folder above it cannot be made online only on its own, so it does not count
+/// towards Make online only.
 pub(crate) fn sync_bulk_bar(ui: &Rc<Ui>) {
     let entries = selected_entries(ui);
     // One selected entry is the details pane's job; the bar is for a batch.
@@ -530,8 +532,7 @@ pub(crate) fn sync_bulk_bar(ui: &Rc<Ui>) {
         ui.browser.bulk.set_reveal_child(false);
         return;
     }
-    let files_only = entries.iter().all(|e| !e.is_dir);
-    let any_pinned = entries.iter().any(|e| e.pinned);
+    let any_pinned = entries.iter().any(|e| e.pinned && !e.pinned_by_folder);
     let any_unpinned = entries.iter().any(|e| !e.pinned);
     let mounted = *ui.mounted.borrow();
     ui.browser.bulk_label.set_label(&ngettext_f(
@@ -541,12 +542,8 @@ pub(crate) fn sync_bulk_bar(ui: &Rc<Ui>) {
         &[],
     ));
     ui.browser.bulk_trash.set_sensitive(mounted);
-    ui.browser
-        .bulk_pin
-        .set_sensitive(mounted && files_only && any_unpinned);
-    ui.browser
-        .bulk_unpin
-        .set_sensitive(mounted && files_only && any_pinned);
+    ui.browser.bulk_pin.set_sensitive(mounted && any_unpinned);
+    ui.browser.bulk_unpin.set_sensitive(mounted && any_pinned);
     ui.browser.bulk.set_reveal_child(true);
 }
 
@@ -652,16 +649,19 @@ pub(crate) fn restore_uids(ui: &Rc<Ui>, uids: Vec<String>, count: usize) {
     );
 }
 
-/// Pin or unpin every selected file, one request at a time.
+/// Pin or unpin every selected entry, one request at a time. A folder's files
+/// download in the background, so its request returns before they are there.
 pub(crate) fn run_bulk_pin(ui: &Rc<Ui>, entries: Vec<DirEntry>, pin: bool) {
     let socket = ui.dirs.control_socket();
     // Only the entries that need changing: re-pinning an already-pinned file is
-    // a wasted round-trip, and it would inflate the count the toast reports.
-    let paths: Vec<String> = entries
+    // a wasted round-trip, and it would inflate the count the toast reports. One
+    // kept through a pinned folder above it has no pin of its own to remove.
+    let changing: Vec<&DirEntry> = entries
         .iter()
-        .filter(|e| !e.is_dir && e.pinned != pin)
-        .map(|e| entry_rel(ui, e))
+        .filter(|e| !e.pinned_by_folder && e.pinned != pin)
         .collect();
+    let any_folder = changing.iter().any(|e| e.is_dir);
+    let paths: Vec<String> = changing.iter().map(|e| entry_rel(ui, e)).collect();
     if paths.is_empty() {
         return;
     }
@@ -698,13 +698,27 @@ pub(crate) fn run_bulk_pin(ui: &Rc<Ui>, entries: Vec<DirEntry>, pin: bool) {
             (0, None) => {}
             (n, _) => toast(
                 &ui,
-                &if pin {
+                &if pin && any_folder {
+                    ngettext_f(
+                        "Making {n} item available offline…",
+                        "Making {n} items available offline…",
+                        n as u64,
+                        &[],
+                    )
+                } else if pin {
                     ngettext_f(
                         "{n} file is now available offline",
                         "{n} files are now available offline",
                         n as u64,
                         &[],
                     )
+                } else if any_folder {
+                    ngettext_f(
+                        "{n} item is now online only",
+                        "{n} items are now online only",
+                        n as u64,
+                        &[],
+                    )
                 } else {
                     ngettext_f(
                         "{n} file is now online only",
@@ -860,13 +874,17 @@ pub(crate) fn entry_context_menu(ui: &Rc<Ui>, entry: &DirEntry) -> ActionMenu {
     }
     menu.section();
 
-    if !entry.is_dir {
+    // Kept through a pinned folder above it, the entry has no pin of its own
+    // to remove: the check shows that state without offering to change it.
+    if entry.pinned_by_folder {
+        menu.locked_toggle(&gettext("Available offline"), true);
+    } else {
         let (ui_c, entry_c) = (ui.clone(), entry.clone());
         menu.toggle(&gettext("Available offline"), entry.pinned, move |_| {
             toggle_pin(&ui_c, &entry_c)
         });
-        menu.section();
     }
+    menu.section();
 
     let (ui_c, entry_c) = (ui.clone(), entry.clone());
     menu.item(&gettext("Share…"), move || {
@@ -886,6 +904,12 @@ pub(crate) fn entry_context_menu(ui: &Rc<Ui>, entry: &DirEntry) -> ActionMenu {
     menu.item(&gettext("Move To…"), move || {
         prompt_move(&ui_c, vec![entry_c.clone()])
     });
+    let (ui_c, entry_c) = (ui.clone(), entry.clone());
+    menu.item(&gettext("Make a Copy"), move || make_copy(&ui_c, &entry_c));
+    let (ui_c, entry_c) = (ui.clone(), entry.clone());
+    menu.item(&gettext("Copy To…"), move || {
+        prompt_copy(&ui_c, vec![entry_c.clone()])
+    });
     if !entry.is_dir {
         let (ui_c, entry_c) = (ui.clone(), entry.clone());
         menu.item(&gettext("Versions…"), move || {
@@ -908,9 +932,8 @@ pub(crate) fn entry_context_menu(ui: &Rc<Ui>, entry: &DirEntry) -> ActionMenu {
 /// simply absent here rather than offered and then refused.
 pub(crate) fn bulk_context_menu(ui: &Rc<Ui>, entries: Vec<DirEntry>) -> ActionMenu {
     let mut menu = ActionMenu::new();
-    // Offline state is a file-only notion; the check shows whether the whole
-    // batch already is.
-    if entries.iter().all(|e| !e.is_dir) {
+    // The check shows whether the whole batch already is offline.
+    {
         let (ui_c, batch) = (ui.clone(), entries.clone());
         let all_pinned = entries.iter().all(|e| e.pinned);
         menu.toggle(&gettext("Available offline"), all_pinned, move |pin| {
@@ -921,6 +944,10 @@ pub(crate) fn bulk_context_menu(ui: &Rc<Ui>, entries: Vec<DirEntry>) -> ActionMe
     menu.item(&gettext("Move To…"), move || {
         prompt_move(&ui_c, batch.clone())
     });
+    let (ui_c, batch) = (ui.clone(), entries.clone());
+    menu.item(&gettext("Copy To…"), move || {
+        prompt_copy(&ui_c, batch.clone())
+    });
     menu.labelled_section(&ngettext_f(
         "{n} selected",
         "{n} selected",
@@ -966,28 +993,27 @@ pub(crate) fn background_context_menu(ui: &Rc<Ui>) -> ActionMenu {
 pub(crate) fn open_entry_with(ui: &Rc<Ui>, entry: &DirEntry) {
     let rel = entry_rel(ui, entry);
     let mountpoint = ui.dirs.resolved_mountpoint(&ui.dirs.load_config());
-    let Some(path) = mounted_target_rel(&mountpoint, &rel) else {
-        toast_error(
-            ui,
-            &gettext("Couldn't open file"),
-            &gettext("Open With needs the Proton Drive service to be running."),
-        );
-        return;
-    };
-    let launcher = gtk4::FileLauncher::new(Some(&gio::File::for_path(path)));
-    launcher.set_always_ask(true);
     let ui = ui.clone();
-    launcher.launch(
-        ui_window(&ui).as_ref(),
-        gio::Cancellable::NONE,
-        move |result| {
+    glib::spawn_future_local(async move {
+        let Some(path) = present_within(mounted_path(&mountpoint, &rel)).await else {
+            toast_error(
+                &ui,
+                &gettext("Couldn't open file"),
+                &gettext("Open With needs the Proton Drive service to be running."),
+            );
+            return;
+        };
+        let launcher = gtk4::FileLauncher::new(Some(&gio::File::for_path(path)));
+        launcher.set_always_ask(true);
+        let window = ui_window(&ui);
+        launcher.launch(window.as_ref(), gio::Cancellable::NONE, move |result| {
             if let Err(e) = result
                 && !e.matches(gtk4::DialogError::Dismissed)
             {
                 toast_error(&ui, &gettext("Couldn't open file"), &e.to_string());
             }
-        },
-    );
+        });
+    });
 }
 
 /// Copy the entry's public link, when it has one this client can read the
@@ -1095,27 +1121,29 @@ pub(crate) fn activate_entry(ui: &Rc<Ui>, entry: &DirEntry) {
 /// [`mounted_target`](crate::activation::mounted_target).
 pub(crate) fn download_and_open(ui: &Rc<Ui>, entry: &DirEntry) {
     let rel = entry_rel(ui, entry);
-    let mountpoint = ui.dirs.resolved_mountpoint(&ui.dirs.load_config());
-    if let Some(path) = mounted_target_rel(&mountpoint, &rel) {
-        open_path(&path.to_string_lossy());
-        return;
-    }
-    // Ignore a repeat activation of a file already downloading, so an impatient
-    // double-click doesn't kick off a second round-trip.
+    // Ignore a repeat activation of a file already opening, so an impatient
+    // double-click doesn't open it twice or kick off a second round-trip.
     if !ui.opening.borrow_mut().insert(rel.clone()) {
         return;
     }
-    ui.busy_begin();
-    let name = entry.name.clone();
-    let rx = spawn_request(
-        ui.dirs.control_socket(),
-        Request::OpenFile {
-            path: rel.clone(),
-            uid: Some(entry.uid.clone()),
-        },
-    );
+    let mountpoint = ui.dirs.resolved_mountpoint(&ui.dirs.load_config());
+    let (name, uid) = (entry.name.clone(), entry.uid.clone());
     let ui = ui.clone();
     glib::spawn_future_local(async move {
+        // Asked off the main thread: a mount that hangs used to hang the app.
+        if let Some(path) = present_within(mounted_path(&mountpoint, &rel)).await {
+            ui.opening.borrow_mut().remove(&rel);
+            open_path(&path.to_string_lossy());
+            return;
+        }
+        ui.busy_begin();
+        let rx = spawn_request(
+            ui.dirs.control_socket(),
+            Request::OpenFile {
+                path: rel.clone(),
+                uid: Some(uid),
+            },
+        );
         let result = rx.recv().await;
         ui.busy_end();
         ui.opening.borrow_mut().remove(&rel);
@@ -1147,6 +1175,7 @@ pub(crate) fn toggle_pin(ui: &Rc<Ui>, entry: &DirEntry) {
     let rx = spawn_request(ui.dirs.control_socket(), req);
     let name = entry.name.clone();
     let pinned = entry.pinned;
+    let is_dir = entry.is_dir;
     let ui = ui.clone();
     glib::spawn_future_local(async move {
         match rx.recv().await {
@@ -1166,6 +1195,9 @@ pub(crate) fn toggle_pin(ui: &Rc<Ui>, entry: &DirEntry) {
                     &ui,
                     &if pinned {
                         gettext_f("“{name}” is now online only", &[("name", &name)])
+                    } else if is_dir {
+                        // The daemon downloads a folder's files in the background.
+                        gettext_f("Making “{name}” available offline…", &[("name", &name)])
                     } else {
                         gettext_f("“{name}” is now available offline", &[("name", &name)])
                     },
@@ -1220,9 +1252,7 @@ pub(crate) fn repaint_crumb(ui: &Rc<Ui>, path: &str) {
     ));
     let mut acc = String::new();
     for (i, seg) in segments.iter().enumerate() {
-        let sep = gtk4::Label::new(Some("›"));
-        sep.add_css_class("dim-label");
-        ui.browser.crumb.append(&sep);
+        ui.browser.crumb.append(&crumb_separator());
         acc = if acc.is_empty() {
             seg.to_string()
         } else {
@@ -1237,12 +1267,7 @@ pub(crate) fn repaint_crumb(ui: &Rc<Ui>, path: &str) {
 /// flat button that navigates to `target` (clearing any active search first).
 pub(crate) fn crumb_node(ui: &Rc<Ui>, label: &str, target: &str, current: bool) -> gtk4::Widget {
     if current {
-        let l = gtk4::Label::builder()
-            .label(label)
-            .ellipsize(gtk4::pango::EllipsizeMode::Start)
-            .build();
-        l.add_css_class("heading");
-        return l.upcast();
+        return crumb_current(label);
     }
     let button = gtk4::Button::builder().label(label).build();
     button.add_css_class("flat");
@@ -1925,17 +1950,63 @@ pub(crate) fn prompt_rename(ui: &Rc<Ui>, entry: &DirEntry) {
 /// still made on Proton Drive, so nothing is downloaded or uploaded again; it
 /// is sent with absolute paths, which is how the daemon tells locations apart.
 pub(crate) fn prompt_move(ui: &Rc<Ui>, entries: Vec<DirEntry>) {
+    prompt_destination(ui, entries, PickerKind::Move);
+}
+
+/// Ask where to copy `entries`, then copy them there on Proton Drive. Only
+/// My files is offered: a copy is made on the server, inside the mount.
+pub(crate) fn prompt_copy(ui: &Rc<Ui>, entries: Vec<DirEntry>) {
+    prompt_destination(ui, entries, PickerKind::Copy);
+}
+
+/// Copy one entry into the folder it is in. The copy gets a free name, such
+/// as "report (1).pdf".
+pub(crate) fn make_copy(ui: &Rc<Ui>, entry: &DirEntry) {
+    let source = entry_rel(ui, entry);
+    let parent = source
+        .rfind('/')
+        .map(|i| source[..i].to_string())
+        .unwrap_or_default();
+    run_bulk_copy(ui, vec![source], parent);
+}
+
+/// What the folder picker chooses a destination for.
+#[derive(Clone, Copy, Debug, PartialEq)]
+pub(crate) enum PickerKind {
+    Move,
+    Copy,
+}
+
+fn prompt_destination(ui: &Rc<Ui>, entries: Vec<DirEntry>, kind: PickerKind) {
     if entries.is_empty() {
         return;
     }
     let sources: Vec<String> = entries.iter().map(|e| entry_rel(ui, e)).collect();
-    let heading = match entries.as_slice() {
-        [one] => gettext_f("Move “{name}”", &[("name", &one.name)]),
-        many => ngettext_f("Move {n} item", "Move {n} items", many.len() as u64, &[]),
+    let (heading, body, confirm) = match (kind, entries.as_slice()) {
+        (PickerKind::Move, [one]) => (
+            gettext_f("Move “{name}”", &[("name", &one.name)]),
+            gettext("Choose the folder to move into."),
+            gettext("Move Here"),
+        ),
+        (PickerKind::Move, many) => (
+            ngettext_f("Move {n} item", "Move {n} items", many.len() as u64, &[]),
+            gettext("Choose the folder to move into."),
+            gettext("Move Here"),
+        ),
+        (PickerKind::Copy, [one]) => (
+            gettext_f("Copy “{name}”", &[("name", &one.name)]),
+            gettext("Choose the folder to copy into."),
+            gettext("Copy Here"),
+        ),
+        (PickerKind::Copy, many) => (
+            ngettext_f("Copy {n} item", "Copy {n} items", many.len() as u64, &[]),
+            gettext("Choose the folder to copy into."),
+            gettext("Copy Here"),
+        ),
     };
     let dialog = adw::AlertDialog::builder()
         .heading(heading)
-        .body(gettext("Choose the folder to move into."))
+        .body(body)
         .build();
 
     let up = gtk4::Button::builder()
@@ -1966,7 +2037,7 @@ pub(crate) fn prompt_move(ui: &Rc<Ui>, entries: Vec<DirEntry>) {
     body.append(&scroll);
     dialog.set_extra_child(Some(&body));
     dialog.add_response("cancel", &gettext("Cancel"));
-    dialog.add_response("move", &gettext("Move Here"));
+    dialog.add_response("move", &confirm);
     dialog.set_response_appearance("move", adw::ResponseAppearance::Suggested);
     dialog.set_default_response(Some("move"));
     dialog.set_close_response("cancel");
@@ -1979,6 +2050,7 @@ pub(crate) fn prompt_move(ui: &Rc<Ui>, entries: Vec<DirEntry>) {
         list,
         up: up.clone(),
         sources: sources.clone(),
+        kind,
         folder: RefCell::new(MoveTarget::Locations),
         generation: Cell::new(0),
     });
@@ -1998,6 +2070,10 @@ pub(crate) fn prompt_move(ui: &Rc<Ui>, entries: Vec<DirEntry>) {
         }
         match picker_done.folder.borrow().clone() {
             MoveTarget::Locations => {}
+            MoveTarget::Drive(folder) if kind == PickerKind::Copy => {
+                run_bulk_copy(&ui, sources.clone(), folder)
+            }
+            MoveTarget::Synced { .. } if kind == PickerKind::Copy => {}
             MoveTarget::Drive(folder) => run_bulk_move(&ui, sources.clone(), folder),
             MoveTarget::Synced { path, .. } => {
                 let absolute = sources
@@ -2073,8 +2149,9 @@ struct MovePicker {
     location: gtk4::Label,
     list: gtk4::ListBox,
     up: gtk4::Button,
-    /// What is being moved, mountpoint-relative.
+    /// What is being moved or copied, mountpoint-relative.
     sources: Vec<String>,
+    kind: PickerKind,
     /// The folder on show, and the destination if the user confirms now.
     folder: RefCell<MoveTarget>,
     /// Drops a listing that arrives after the user went elsewhere.
@@ -2095,11 +2172,13 @@ impl MovePicker {
         self.location.set_tooltip_text(Some(&tooltip));
         self.up
             .set_sensitive(!matches!(folder, MoveTarget::Locations));
-        let allowed = match &folder {
-            MoveTarget::Locations => false,
-            MoveTarget::Drive(rel) => move_target_allowed(&self.sources, rel),
+        let allowed = match (&folder, self.kind) {
+            (MoveTarget::Locations, _) => false,
+            (MoveTarget::Drive(rel), PickerKind::Move) => move_target_allowed(&self.sources, rel),
+            (MoveTarget::Drive(rel), PickerKind::Copy) => copy_target_allowed(&self.sources, rel),
             // What is moved is in My files, so it cannot be in a synced folder.
-            MoveTarget::Synced { .. } => true,
+            (MoveTarget::Synced { .. }, PickerKind::Move) => true,
+            (MoveTarget::Synced { .. }, PickerKind::Copy) => false,
         };
         self.dialog.set_response_enabled("move", allowed);
         *self.folder.borrow_mut() = folder.clone();
@@ -2165,6 +2244,10 @@ impl MovePicker {
     /// My files and every synced folder, as rows of the top level.
     async fn locations(&self) -> Option<Vec<PickerRow>> {
         let mut rows = vec![(gettext("My files"), None, MoveTarget::Drive(String::new()))];
+        // A copy is made on the server, so it can only land in My files.
+        if self.kind == PickerKind::Copy {
+            return Some(rows);
+        }
         let rx = spawn_request(self.ui.dirs.control_socket(), Request::ListSyncFolders);
         let Ok(Ok(Response::SyncFolders { mut items })) = rx.recv().await else {
             // My files alone is still somewhere to move to.
@@ -2271,11 +2354,16 @@ pub(crate) fn move_target_allowed(sources: &[String], target: &str) -> bool {
             .map(|i| path[..i].to_string())
             .unwrap_or_default()
     };
-    let inside = sources
-        .iter()
-        .any(|src| target == src || target.starts_with(&format!("{src}/")));
     let all_here = sources.iter().all(|src| parent(src) == target);
-    !inside && !all_here
+    copy_target_allowed(sources, target) && !all_here
+}
+
+/// Whether `target` is somewhere `sources` can be copied to: anywhere but into
+/// one of themselves. The folder they are in is fine; the copy gets a free name.
+pub(crate) fn copy_target_allowed(sources: &[String], target: &str) -> bool {
+    !sources
+        .iter()
+        .any(|src| target == src || target.starts_with(&format!("{src}/")))
 }
 
 /// Move each of `sources` into `target`, one request at a time, then report
@@ -2294,38 +2382,14 @@ pub(crate) fn run_bulk_move(ui: &Rc<Ui>, sources: Vec<String>, target: String) {
     clear_selection(ui);
     let ui = ui.clone();
     glib::spawn_future_local(async move {
-        let mut done = 0usize;
-        let mut failure: Option<(String, ErrorKind)> = None;
-        for path in sources {
-            let rx = spawn_request(
-                socket.clone(),
-                Request::Move {
-                    path,
-                    new_parent: target.clone(),
-                },
-            );
-            match rx.recv().await {
-                Ok(Ok(Response::Ok { .. })) => done += 1,
-                Ok(Ok(Response::Error { message, kind })) => {
-                    failure.get_or_insert((message, kind));
-                }
-                _ => {
-                    failure.get_or_insert_with(|| {
-                        (
-                            gettext("The Proton Drive service didn't respond."),
-                            ErrorKind::Internal,
-                        )
-                    });
-                }
-            }
-        }
+        let (done, failure) = send_each(&socket, sources, |path| Request::Move {
+            path,
+            new_parent: target.clone(),
+        })
+        .await;
         ui.busy_end();
         reload_listing(&ui);
-        let place = match target.rsplit('/').next() {
-            // Translators: a folder name in quotes, filled in as {place} in "Moved to {place}".
-            Some(name) if !name.is_empty() => gettext_f("“{name}”", &[("name", name)]),
-            _ => "Proton Drive".to_string(),
-        };
+        let place = quoted_place(&target);
         match (done, failure) {
             (0, Some((message, kind))) => {
                 toast_failure(&ui, &gettext("Couldn't move"), &message, kind)
@@ -2358,6 +2422,101 @@ pub(crate) fn run_bulk_move(ui: &Rc<Ui>, sources: Vec<String>, target: String) {
     });
 }
 
+/// Copy each of `sources` into `target` on Proton Drive, one request at a
+/// time, then report once for the lot.
+pub(crate) fn run_bulk_copy(ui: &Rc<Ui>, sources: Vec<String>, target: String) {
+    if !*ui.mounted.borrow() {
+        toast_error(
+            ui,
+            &gettext("Couldn't copy"),
+            &gettext("Proton Drive isn't connected."),
+        );
+        return;
+    }
+    let socket = ui.dirs.control_socket();
+    ui.busy_begin();
+    clear_selection(ui);
+    let ui = ui.clone();
+    glib::spawn_future_local(async move {
+        let (done, failure) = send_each(&socket, sources, |path| Request::Copy {
+            path,
+            new_parent: target.clone(),
+        })
+        .await;
+        ui.busy_end();
+        reload_listing(&ui);
+        let place = quoted_place(&target);
+        match (done, failure) {
+            (0, Some((message, kind))) => {
+                toast_failure(&ui, &gettext("Couldn't copy"), &message, kind)
+            }
+            (0, None) => {}
+            (n, Some((message, _))) => toast_error(
+                &ui,
+                // Translators: {place} is a quoted folder name or "Proton Drive".
+                &ngettext_f(
+                    "Copied {n} item to {place}, but not all",
+                    "Copied {n} items to {place}, but not all",
+                    n as u64,
+                    &[("place", &place)],
+                ),
+                &message,
+            ),
+            // Translators: {place} is a quoted folder name or "Proton Drive".
+            (1, None) => toast(&ui, &gettext_f("Copied to {place}", &[("place", &place)])),
+            (n, None) => toast(
+                &ui,
+                // Translators: {place} is a quoted folder name or "Proton Drive".
+                &ngettext_f(
+                    "Copied {n} item to {place}",
+                    "Copied {n} items to {place}",
+                    n as u64,
+                    &[("place", &place)],
+                ),
+            ),
+        }
+    });
+}
+
+/// Send one request per source, in order, and count how many succeeded. The
+/// first failure is kept for the report.
+async fn send_each(
+    socket: &Path,
+    sources: Vec<String>,
+    request: impl Fn(String) -> Request,
+) -> (usize, Option<(String, ErrorKind)>) {
+    let mut done = 0usize;
+    let mut failure: Option<(String, ErrorKind)> = None;
+    for path in sources {
+        let rx = spawn_request(socket.to_path_buf(), request(path));
+        match rx.recv().await {
+            Ok(Ok(Response::Ok { .. })) => done += 1,
+            Ok(Ok(Response::Error { message, kind })) => {
+                failure.get_or_insert((message, kind));
+            }
+            _ => {
+                failure.get_or_insert_with(|| {
+                    (
+                        gettext("The Proton Drive service didn't respond."),
+                        ErrorKind::Internal,
+                    )
+                });
+            }
+        }
+    }
+    (done, failure)
+}
+
+/// The destination folder for a report: its name in quotes, or "Proton Drive"
+/// for My files.
+fn quoted_place(target: &str) -> String {
+    match target.rsplit('/').next() {
+        // Translators: a folder name in quotes, filled in as {place} in "Moved to {place}".
+        Some(name) if !name.is_empty() => gettext_f("“{name}”", &[("name", name)]),
+        _ => "Proton Drive".to_string(),
+    }
+}
+
 /// Move one entry to Trash, through the batch path so it gets the same Undo.
 pub(crate) fn trash_entry(ui: &Rc<Ui>, entry: &DirEntry) {
     run_bulk_delete(ui, vec![entry.clone()]);
@@ -2494,16 +2653,19 @@ pub(crate) fn start_upload(ui: &Rc<Ui>, sources: Vec<String>) {
     });
 }
 
-/// The sync-state badge for an entry: `(icon, css-class)`, or `None` for folders
-/// (which carry no per-file cache state). A sync issue ranks first, on folders
-/// too: the change waits for the user. Pinned (kept offline) ranks above merely
-/// cached (downloaded, evictable); everything else is online-only.
+/// The sync-state badge for an entry: `(icon, css-class)`. A folder carries no
+/// cache state of its own, so it has one only when kept offline. A sync issue
+/// ranks first, on folders too: the change waits for the user. Pinned (kept
+/// offline) ranks above merely cached (downloaded, evictable); everything else
+/// is online-only.
 pub(crate) fn badge_for(entry: &DirEntry) -> Option<(&'static str, &'static str)> {
     if entry.issue.is_some() {
         return Some(("dialog-warning-symbolic", "badge-issue"));
     }
     if entry.is_dir {
-        return None;
+        return entry
+            .pinned
+            .then_some(("pdfs-offline-symbolic", "badge-pinned"));
     }
     Some(if entry.pinned {
         ("pdfs-offline-symbolic", "badge-pinned")
@@ -2912,6 +3074,7 @@ pub(crate) fn repaint_search(ui: &Rc<Ui>, hits: &[SearchHit]) {
             size: h.size,
             modified: h.modified,
             pinned: h.pinned,
+            pinned_by_folder: false,
             cached: h.cached,
             uid: h.uid.clone(),
             path: h.path.clone(),
@@ -2959,8 +3122,8 @@ fn listing_summary(files: usize, folders: usize, file_bytes: u64) -> String {
 #[cfg(test)]
 mod tests {
     use super::{
-        MoveTarget, badge_for, hit_location, listing_summary, move_target_allowed,
-        show_thumbnail_build_progress, sort_entries,
+        MoveTarget, badge_for, copy_target_allowed, hit_location, listing_summary,
+        move_target_allowed, show_thumbnail_build_progress, sort_entries,
     };
     use pdfs_core::config::{FileSort, FilesView};
     use pdfs_core::control::{DirEntry, SyncIssue, ThumbnailBuildStatus};
@@ -2972,6 +3135,7 @@ mod tests {
             size,
             modified,
             pinned: false,
+            pinned_by_folder: false,
             cached: false,
             uid: String::new(),
             path: String::new(),
@@ -2999,6 +3163,8 @@ mod tests {
 
         let mut folder = entry("d", true, 0, 0);
         assert_eq!(badge_for(&folder), None);
+        folder.pinned = true;
+        assert_eq!(badge_for(&folder).unwrap().1, "badge-pinned");
         folder.issue = Some(SyncIssue::Missing);
         assert_eq!(badge_for(&folder).unwrap().1, "badge-issue");
     }
@@ -3045,6 +3211,16 @@ mod tests {
         assert!(move_target_allowed(&mixed, ""));
     }
 
+    #[test]
+    fn copy_refuses_its_own_subtree_but_not_the_folder_it_is_in() {
+        let sources = ["Docs/Work".to_string()];
+        assert!(!copy_target_allowed(&sources, "Docs/Work"));
+        assert!(!copy_target_allowed(&sources, "Docs/Work/Old"));
+        assert!(copy_target_allowed(&sources, "Docs"));
+        assert!(copy_target_allowed(&sources, ""));
+        assert!(copy_target_allowed(&sources, "Docs/Workshop"));
+    }
+
     #[test]
     fn listing_summary_matches_dolphin_order_and_wording() {
         assert_eq!(listing_summary(0, 0, 0), "0 folders, 0 files");

crates/pdfs-gui/src/app/pages/devices.rs

@@ -204,7 +204,9 @@ pub(crate) fn wire_devices(ui: &Rc<Ui>, widgets: &DevicesWidgets) {
 pub(crate) fn devices_status(ui: &Rc<Ui>, icon: &str, title: &str, description: &str, retry: bool) {
     ui.devices.status.set_icon_name(Some(icon));
     ui.devices.status.set_title(title);
-    ui.devices.status.set_description(Some(description));
+    ui.devices
+        .status
+        .set_description(Some(&gtk4::glib::markup_escape_text(description)));
     ui.devices.retry.set_visible(retry);
     ui.devices.content.set_visible_child_name("status");
 }
@@ -390,6 +392,7 @@ fn this_computer_row(
     let row = adw::ActionRow::builder()
         .title(me.map_or_else(|| gettext("This computer"), |d| d.name.clone()))
         .subtitle(this_computer_subtitle(folders))
+        .use_markup(false)
         .activatable(true)
         .build();
     row.add_prefix(&gtk4::Image::from_icon_name("computer-symbolic"));
@@ -426,6 +429,7 @@ fn other_computer_row(ui: &Rc<Ui>, dev: &DeviceInfo) -> adw::ActionRow {
     let row = adw::ActionRow::builder()
         .title(&dev.name)
         .subtitle(device_subtitle(dev))
+        .use_markup(false)
         .activatable(true)
         .build();
     row.add_prefix(&gtk4::Image::from_icon_name("computer-symbolic"));
@@ -439,6 +443,14 @@ fn other_computer_row(ui: &Rc<Ui>, dev: &DeviceInfo) -> adw::ActionRow {
     menu.item(&gettext("Restore to This Computer…"), move || {
         prompt_restore_folders(&ui_c, Some((uid_c.clone(), name_c.clone())))
     });
+    let (ui_c, uid_c, name_c) = (ui.clone(), uid.clone(), name.clone());
+    menu.item(&gettext("Sync With This Computer…"), move || {
+        prompt_join_device(&ui_c, &uid_c, &name_c)
+    });
+    let (ui_c, uid_c, name_c) = (ui.clone(), uid.clone(), name.clone());
+    menu.item(&gettext("Move to This Computer…"), move || {
+        prompt_migrate_device(&ui_c, &uid_c, &name_c)
+    });
     menu.section();
     let (ui_c, uid_c, name_c) = (ui.clone(), uid.clone(), name.clone());
     menu.item(&gettext("Rename…"), move || {
@@ -483,9 +495,7 @@ fn repaint_device_crumb(ui: &Rc<Ui>, nav: &[(String, String)]) {
         nav.is_empty(),
     ));
     for (i, (_, name)) in nav.iter().enumerate() {
-        let sep = gtk4::Label::new(Some("›"));
-        sep.add_css_class("dim-label");
-        crumb.append(&sep);
+        crumb.append(&crumb_separator());
         crumb.append(&device_crumb_node(ui, name, i + 1, i + 1 == nav.len()));
     }
 }
@@ -494,12 +504,7 @@ fn repaint_device_crumb(ui: &Rc<Ui>, nav: &[(String, String)]) {
 /// that goes back up to `depth` levels below the device list.
 fn device_crumb_node(ui: &Rc<Ui>, label: &str, depth: usize, current: bool) -> gtk4::Widget {
     if current {
-        let l = gtk4::Label::builder()
-            .label(label)
-            .ellipsize(gtk4::pango::EllipsizeMode::Start)
-            .build();
-        l.add_css_class("heading");
-        return l.upcast();
+        return crumb_current(label);
     }
     let button = gtk4::Button::builder().label(label).build();
     button.add_css_class("flat");
@@ -592,6 +597,19 @@ pub(crate) fn this_computer_subtitle(folders: &[SyncFolderInfo]) -> String {
         folders.len() as u64,
         &[],
     );
+    // A folder whose first pass has not run is not backed up yet, whatever its
+    // state column says (`docs/BUGS.md` B261).
+    let waiting = folders.iter().filter(|f| never_synced(f)).count();
+    let count = match waiting {
+        0 => count,
+        // Translators: {folders} is "N folders backed up"; {n} counts the folders whose first sync has not run yet.
+        n => ngettext_f(
+            "{folders} · {n} waiting for its first sync",
+            "{folders} · {n} waiting for their first sync",
+            n as u64,
+            &[("folders", &count)],
+        ),
+    };
     let attention = folders
         .iter()
         .filter(|f| f.state == "error" || f.state == "conflict")
@@ -608,12 +626,21 @@ pub(crate) fn this_computer_subtitle(folders: &[SyncFolderInfo]) -> String {
     }
 }
 
-/// Human label for a synced folder's `state` column.
-pub(crate) fn sync_state_label(state: &str) -> String {
+/// Whether a synced folder is a mirror whose first pass has not finished.
+/// Its `state` starts out `idle`, which would read as "up to date".
+fn never_synced(folder: &SyncFolderInfo) -> bool {
+    folder.mode == "mirror" && folder.last_sync == 0 && folder.state == "idle"
+}
+
+/// Human label for a synced folder's `state` column. `never_synced` is a
+/// mirror folder whose first pass has not finished: its `state` starts out
+/// `idle`, and "up to date" would say the opposite of the truth (B261).
+pub(crate) fn sync_state_label(state: &str, never_synced: bool) -> String {
     match state {
         "syncing" => gettext("syncing…"),
         "error" => gettext("sync error"),
         "conflict" => gettext("needs attention"),
+        _ if never_synced => gettext("waiting for first sync"),
         _ => gettext("up to date"),
     }
 }
@@ -624,9 +651,17 @@ pub(crate) fn sync_state_label(state: &str) -> String {
 /// — so both read "12 of 40" rather than a percentage that could go backwards.
 pub(crate) fn sync_progress_label(p: &SyncProgress) -> String {
     match p.phase {
-        // Before the first pass finishes there is no estimate, so the count would
-        // be "checked 12 of 12" — worse than saying nothing.
-        SyncPhase::Scanning if p.total == 0 => gettext("checking for changes…"),
+        SyncPhase::Scanning if p.total == 0 && p.done == 0 => gettext("checking for changes…"),
+        // Before the first pass finishes there is no estimate, so "12 of 12" would
+        // say nothing. The count alone still shows a first scan of a large folder
+        // moving, which can take many minutes before anything downloads.
+        // Translators: {n} counts the folders and files checked so far.
+        SyncPhase::Scanning if p.total == 0 => ngettext_f(
+            "checking for changes — {n} item checked",
+            "checking for changes — {n} items checked",
+            p.done as u64,
+            &[],
+        ),
         // Translators: {done} and {total} count folders and files checked so far.
         SyncPhase::Scanning => gettext_f(
             "checking for changes — {done} of {total}",
@@ -766,7 +801,10 @@ fn show_restore_picker(
             .active(true)
             .valign(gtk4::Align::Center)
             .build();
-        let row = adw::EntryRow::builder().title(&f.name).build();
+        let row = adw::EntryRow::builder()
+            .title(&f.name)
+            .use_markup(false)
+            .build();
         row.set_text(&f.local_path);
         row.add_prefix(&check);
         group.add(&row);
@@ -1096,6 +1134,130 @@ pub(crate) fn prompt_adopt_device(ui: &Rc<Ui>, uid: &str, name: &str) {
     dialog.present(win.as_ref());
 }
 
+/// Ask before syncing into another computer's device alongside it, then offer
+/// its folders for syncing here.
+///
+/// The same adoption as "Continue This Backup Here", but the other computer
+/// goes on syncing, so the dialog says what that means: the two keep the same
+/// folders in step, deletions included.
+pub(crate) fn prompt_join_device(ui: &Rc<Ui>, uid: &str, name: &str) {
+    let win = ui_window(ui);
+    let dialog = adw::AlertDialog::builder()
+        .heading(gettext("Sync With This Computer?"))
+        // Translators: {name} is the name of the other computer this one syncs with.
+        .body(gettext_f(
+            "This computer and “{name}” keep the same folders in step. A change or a deletion on one reaches the other.\n\nNew synced folders on this computer go under “{name}” in Proton Drive. Folders already synced here stay where they are. Next you choose which of its folders to sync here.",
+            &[("name", name)],
+        ))
+        .build();
+    dialog.add_response("cancel", &gettext("Cancel"));
+    dialog.add_response("join", &gettext("Sync Here"));
+    dialog.set_response_appearance("join", adw::ResponseAppearance::Suggested);
+    dialog.set_default_response(Some("cancel"));
+    dialog.set_close_response("cancel");
+    let ui = ui.clone();
+    let uid = uid.to_string();
+    // Translators: {name} is the name of the other computer this one now syncs with.
+    let done = gettext_f("Now syncing with “{name}”", &[("name", name)]);
+    dialog.connect_response(None, move |_, resp| {
+        if resp != "join" {
+            return;
+        }
+        ui.busy_begin();
+        let rx = spawn_request(
+            ui.dirs.control_socket(),
+            Request::AdoptDevice {
+                uid: Some(uid.clone()),
+            },
+        );
+        let (ui, done) = (ui.clone(), done.clone());
+        glib::spawn_future_local(async move {
+            let result = rx.recv().await;
+            ui.busy_end();
+            let failed = gettext("Couldn't sync with that computer");
+            match result {
+                Ok(Ok(Response::Ok { .. })) => {
+                    reload_sync_pages(&ui);
+                    toast(&ui, &done);
+                    // The device is this computer's now, so its own restore
+                    // picker offers the folders.
+                    prompt_restore_folders(&ui, None);
+                }
+                Ok(Ok(Response::Error { message, kind })) => {
+                    toast_failure(&ui, &failed, &message, kind)
+                }
+                _ => toast_error(
+                    &ui,
+                    &failed,
+                    &gettext("The Proton Drive service didn't respond."),
+                ),
+            }
+        });
+    });
+    dialog.present(win.as_ref());
+}
+
+/// Ask before moving another computer's folders into this computer's backup,
+/// then offer them for syncing here.
+///
+/// Destructive-looking on purpose: the other computer keeps its device but
+/// loses its folders, and a copy of Proton Drive still running there would
+/// watch them vanish.
+pub(crate) fn prompt_migrate_device(ui: &Rc<Ui>, uid: &str, name: &str) {
+    let win = ui_window(ui);
+    let dialog = adw::AlertDialog::builder()
+        .heading(gettext("Move Backup to This Computer?"))
+        // Translators: {name} is the name of the other computer whose folders move to this one.
+        .body(gettext_f(
+            "The folders backed up by “{name}” move into this computer's backup in Proton Drive, and you choose where they go on this computer. “{name}” stays in your account, without those folders.\n\nStop Proton Drive on “{name}” first. Otherwise it sees its folders disappear.",
+            &[("name", name)],
+        ))
+        .build();
+    dialog.add_response("cancel", &gettext("Cancel"));
+    dialog.add_response("move", &gettext("Move Here"));
+    dialog.set_response_appearance("move", adw::ResponseAppearance::Destructive);
+    dialog.set_default_response(Some("cancel"));
+    dialog.set_close_response("cancel");
+    let ui = ui.clone();
+    let uid = uid.to_string();
+    // Translators: {name} is the name of the computer whose folders moved to this one.
+    let done = gettext_f("Moved the backup of “{name}”", &[("name", name)]);
+    dialog.connect_response(None, move |_, resp| {
+        if resp != "move" {
+            return;
+        }
+        ui.busy_begin();
+        let rx = spawn_request(
+            ui.dirs.control_socket(),
+            Request::MigrateDevice { uid: uid.clone() },
+        );
+        let (ui, done) = (ui.clone(), done.clone());
+        glib::spawn_future_local(async move {
+            let result = rx.recv().await;
+            ui.busy_end();
+            let failed = gettext("Couldn't move that backup");
+            match result {
+                Ok(Ok(Response::Ok { .. })) => {
+                    reload_sync_pages(&ui);
+                    toast(&ui, &done);
+                    // The folders are this computer's now, so its own restore
+                    // picker is where the user chooses their local paths.
+                    prompt_restore_folders(&ui, None);
+                }
+                Ok(Ok(Response::Error { message, kind })) => {
+                    toast_failure(&ui, &failed, &message, kind)
+                }
+                _ => toast_error(
+                    &ui,
+                    &failed,
+                    &gettext("The Proton Drive service didn't respond."),
+                ),
+            }
+        });
+    });
+    dialog.present(win.as_ref());
+}
+
 /// Run a mutation raised from Computers or Locations and reload the page on success.
 pub(crate) fn run_devices_mutation(ui: &Rc<Ui>, req: Request, done: &str, failed: &str) {
     ui.busy_begin();
@@ -1134,7 +1296,7 @@ mod tests {
             remote_uid: "vol~link".into(),
             mode: "mirror".into(),
             state: state.into(),
-            last_sync: 0,
+            last_sync: 1_700_000_000,
             pending_mode: None,
             progress: None,
             paused: false,
@@ -1146,6 +1308,33 @@ mod tests {
         assert_eq!(this_computer_subtitle(&[]), "No folders backed up yet");
     }
 
+    /// A folder added a moment ago is not backed up yet, and the row must not
+    /// say it is (`docs/BUGS.md` B261). An on-demand folder has no first sync.
+    #[test]
+    fn a_folder_before_its_first_sync_is_not_counted_as_backed_up() {
+        let new = SyncFolderInfo {
+            last_sync: 0,
+            ..folder("idle")
+        };
+        assert_eq!(
+            this_computer_subtitle(&[folder("idle"), new.clone()]),
+            "2 folders backed up · 1 waiting for its first sync"
+        );
+        let failed = SyncFolderInfo {
+            state: "error".into(),
+            ..new.clone()
+        };
+        assert_eq!(
+            this_computer_subtitle(&[new.clone(), failed]),
+            "2 folders backed up · 1 waiting for its first sync · 1 needs attention"
+        );
+        let on_demand = SyncFolderInfo {
+            mode: "ondemand".into(),
+            ..new
+        };
+        assert_eq!(this_computer_subtitle(&[on_demand]), "1 folder backed up");
+    }
+
     #[test]
     fn folders_needing_attention_are_counted_not_hidden() {
         // The per-folder rows live on the Sync page, so this row is the only
@@ -1164,6 +1353,37 @@ mod tests {
         );
     }
 
+    fn scanning(done: usize, total: usize) -> SyncProgress {
+        SyncProgress {
+            phase: SyncPhase::Scanning,
+            done,
+            total,
+            current: String::new(),
+        }
+    }
+
+    #[test]
+    fn a_first_scan_counts_what_it_checked() {
+        // A first sync of a large folder scans for many minutes before anything
+        // downloads; without a count it reads as stuck (#46).
+        assert_eq!(
+            sync_progress_label(&scanning(0, 0)),
+            "checking for changes…"
+        );
+        assert_eq!(
+            sync_progress_label(&scanning(1, 0)),
+            "checking for changes — 1 item checked"
+        );
+        assert_eq!(
+            sync_progress_label(&scanning(1234, 0)),
+            "checking for changes — 1234 items checked"
+        );
+        assert_eq!(
+            sync_progress_label(&scanning(12, 40)),
+            "checking for changes — 12 of 40"
+        );
+    }
+
     #[test]
     fn the_restore_picker_names_the_computer_it_restores_from() {
         assert!(restore_picker_body(Some("laptop")).contains("“laptop”"));

crates/pdfs-gui/src/app/pages/duplicates.rs

@@ -209,7 +209,8 @@ fn ask(view: &Rc<FinderView>, finder: Finder, generation: u32) {
             Ok(Ok(Response::Error { message, .. })) => {
                 view.status.set_icon_name(Some("dialog-warning-symbolic"));
                 view.status.set_title(&failed);
-                view.status.set_description(Some(&message));
+                view.status
+                    .set_description(Some(&gtk4::glib::markup_escape_text(&message)));
                 view.progress.set_visible(false);
                 return;
             }

crates/pdfs-gui/src/app/pages/locations.rs

@@ -46,6 +46,10 @@ pub(crate) struct SyncCard {
     pub(crate) pause: adw::SplitButton,
     /// Whether the last status said paused, so the button knows which way to go.
     pub(crate) paused: Cell<bool>,
+    /// Shown only while Proton refuses the session; opens the sign-in page.
+    pub(crate) sign_in: gtk4::Button,
+    /// Shown only while the daemon is older than the app; restarts it.
+    pub(crate) restart: gtk4::Button,
 }
 
 /// What a folder row's controls are built from. The subtitle and progress bar
@@ -108,6 +112,8 @@ pub(crate) struct LocationsWidgets {
     pub(crate) card_icon: gtk4::Image,
     pub(crate) card_title: gtk4::Label,
     pub(crate) card_detail: gtk4::Label,
+    pub(crate) card_sign_in: gtk4::Button,
+    pub(crate) card_restart: gtk4::Button,
     pub(crate) pause: adw::SplitButton,
     pub(crate) queue_group: adw::PreferencesGroup,
     pub(crate) retry_all: gtk4::Button,
@@ -134,7 +140,7 @@ pub(crate) fn build_locations_page(history: &gtk4::Widget) -> (gtk4::Widget, Loc
         .build();
     add_folder.add_css_class("flat");
     let transfers_group = build_transfers_group();
-    let (card, card_icon, card_title, card_detail) = build_sync_card();
+    let (card, card_icon, card_title, card_detail, card_sign_in, card_restart) = build_sync_card();
     let pause = build_pause_button();
     let (queue_group, retry_all) = build_queue_group();
     let conflicts_group = adw::PreferencesGroup::builder()
@@ -253,6 +259,8 @@ pub(crate) fn build_locations_page(history: &gtk4::Widget) -> (gtk4::Widget, Loc
         card_icon,
         card_title,
         card_detail,
+        card_sign_in,
+        card_restart,
         pause,
         queue_group,
         retry_all,
@@ -290,6 +298,16 @@ pub(crate) fn wire_locations(ui: &Rc<Ui>, retry: &gtk4::Button, add_folder: &gtk
     let ui_add = ui.clone();
     add_folder.connect_clicked(move |_| prompt_add_sync_folder(&ui_add));
     wire_pause(ui);
+    let ui_sign_in = ui.clone();
+    ui.locations
+        .card
+        .sign_in
+        .connect_clicked(move |_| show_login(&ui_sign_in));
+    let ui_restart = ui.clone();
+    ui.locations
+        .card
+        .restart
+        .connect_clicked(move |_| restart_service_then(&ui_restart, |_| {}));
     let ui_retry = ui.clone();
     ui.locations
         .queue
@@ -379,9 +397,16 @@ pub(crate) fn paint_sync_banner(ui: &Rc<Ui>) {
     state.banner.set_revealed(away && title.is_some());
 }
 
-/// The status hero: a large state icon, the state in words, and what it
-/// means.
-fn build_sync_card() -> (gtk4::Box, gtk4::Image, gtk4::Label, gtk4::Label) {
+/// The status hero: a large state icon, the state in words, what it means,
+/// and the way out when there is one only the user can take.
+fn build_sync_card() -> (
+    gtk4::Box,
+    gtk4::Image,
+    gtk4::Label,
+    gtk4::Label,
+    gtk4::Button,
+    gtk4::Button,
+) {
     let icon = gtk4::Image::builder()
         .icon_name("pdfs-sync-symbolic")
         .pixel_size(48)
@@ -408,9 +433,25 @@ fn build_sync_card() -> (gtk4::Box, gtk4::Image, gtk4::Label, gtk4::Label) {
     let card = gtk4::Box::new(gtk4::Orientation::Horizontal, 18);
     card.add_css_class("card");
     card.add_css_class("sync-card");
+    let sign_in = gtk4::Button::builder()
+        .label(gettext("Sign In Again"))
+        .valign(gtk4::Align::Center)
+        .visible(false)
+        .build();
+    sign_in.add_css_class("pill");
+    sign_in.add_css_class("suggested-action");
+    let restart = gtk4::Button::builder()
+        .label(gettext("Restart"))
+        .valign(gtk4::Align::Center)
+        .visible(false)
+        .build();
+    restart.add_css_class("pill");
+    restart.add_css_class("suggested-action");
     card.append(&icon);
     card.append(&text);
-    (card, icon, title, detail)
+    card.append(&sign_in);
+    card.append(&restart);
+    (card, icon, title, detail, sign_in, restart)
 }
 
 /// Pause/Resume, with timed pauses in its menu.
@@ -1104,7 +1145,9 @@ pub(crate) fn locations_status(
 ) {
     ui.locations.status.set_icon_name(Some(icon));
     ui.locations.status.set_title(title);
-    ui.locations.status.set_description(Some(description));
+    ui.locations
+        .status
+        .set_description(Some(&gtk4::glib::markup_escape_text(description)));
     ui.locations.retry.set_visible(retry);
     ui.locations.content.set_visible_child_name("status");
 }
@@ -1463,8 +1506,13 @@ fn add_device_items(ui: &Rc<Ui>, menu: &mut ActionMenu, spec: &MountSpec, id: i6
         } else {
             gettext("Pause Syncing")
         };
+        let ui_pause = ui.clone();
+        menu.item(&label, move || set_folder_paused(&ui_pause, id, !paused));
         let ui = ui.clone();
-        menu.item(&label, move || set_folder_paused(&ui, id, !paused));
+        let path = spec.local_path.clone();
+        menu.item(&gettext("Sync From Scratch…"), move || {
+            confirm_reset_sync_folder(&ui, id, &path)
+        });
         menu.section();
     }
     let ui = ui.clone();
@@ -1477,6 +1525,51 @@ fn add_device_items(ui: &Rc<Ui>, menu: &mut ActionMenu, spec: &MountSpec, id: i6
     });
 }
 
+/// Ask before syncing a folder from scratch. Nothing is deleted, but files
+/// that differ come back as conflict copies, so it is not a click to make by
+/// accident.
+fn confirm_reset_sync_folder(ui: &Rc<Ui>, id: i64, path: &str) {
+    let dialog = adw::AlertDialog::builder()
+        .heading(gettext("Sync From Scratch?"))
+        // Translators: {path} is a local folder path.
+        .body(gettext_f("This computer forgets what it synced in {path} before and compares the folder with Proton Drive again. Nothing is deleted: a file on one side only is copied to the other, and a file that differs keeps both versions.", &[("path", path)]))
+        .build();
+    dialog.add_response("cancel", &gettext("Cancel"));
+    dialog.add_response("reset", &gettext("Sync From Scratch"));
+    dialog.set_response_appearance("reset", adw::ResponseAppearance::Suggested);
+    dialog.set_default_response(Some("cancel"));
+    dialog.set_close_response("cancel");
+    let win = ui_window(ui);
+    let ui = ui.clone();
+    dialog.connect_response(None, move |_, response| {
+        if response == "reset" {
+            reset_sync_folder(&ui, id);
+        }
+    });
+    dialog.present(win.as_ref());
+}
+
+/// Forget a folder's sync records, then repaint so its row shows the new pass.
+fn reset_sync_folder(ui: &Rc<Ui>, id: i64) {
+    let rx = spawn_request(ui.dirs.control_socket(), Request::ResetSyncFolder { id });
+    let ui = ui.clone();
+    glib::spawn_future_local(async move {
+        let failed = gettext("Couldn't sync the folder from scratch");
+        match rx.recv().await {
+            Ok(Ok(Response::Ok { .. })) => toast(&ui, &gettext("Syncing folder…")),
+            Ok(Ok(Response::Error { message, kind })) => {
+                toast_failure(&ui, &failed, &message, kind)
+            }
+            _ => toast_error(
+                &ui,
+                &failed,
+                &gettext("The Proton Drive service didn't respond."),
+            ),
+        }
+        refresh_locations(&ui);
+    });
+}
+
 /// Ask before making a synced folder online only: the switch frees disk space
 /// by removing the local copies, which is not something to do by accident.
 fn confirm_online_only(ui: &Rc<Ui>, id: i64, path: &str) {
@@ -1636,7 +1729,10 @@ pub(crate) fn location_subtitle(spec: &MountSpec) -> String {
         parts.push(match &spec.progress {
             Some(p) => sync_progress_label(p),
             None if spec.paused => pgettext("state", "paused"),
-            None => sync_state_label(&spec.state).to_string(),
+            None => sync_state_label(
+                &spec.state,
+                spec.mode == MountMode::Mirror && spec.last_sync == 0,
+            ),
         });
     }
     // Only the locations that are supposed to have a session report its absence:
@@ -1682,7 +1778,25 @@ mod tests {
             MountMode::Mirror,
             false,
         );
+        assert_eq!(location_subtitle(&spec), "Synced · waiting for first sync");
+    }
+
+    /// A folder whose first pass has not run is not up to date, though its
+    /// state column starts out `idle` (`docs/BUGS.md` B261).
+    #[test]
+    fn a_folder_reads_up_to_date_only_after_its_first_sync() {
+        let mut spec = spec(
+            MountKind::Device { sync_folder_id: 7 },
+            MountMode::Mirror,
+            false,
+        );
+        assert_eq!(location_subtitle(&spec), "Synced · waiting for first sync");
+        spec.last_sync = 1_700_000_000;
         assert_eq!(location_subtitle(&spec), "Synced · up to date");
+        // A folder that failed before it ever synced says so.
+        spec.last_sync = 0;
+        spec.state = "error".into();
+        assert_eq!(location_subtitle(&spec), "Synced · sync error");
     }
 
     #[test]

crates/pdfs-gui/src/app/pages/login.rs

@@ -1,5 +1,5 @@
 use crate::*;
-use pdfs_core::proton_sdk::api::HumanVerificationCredential;
+use pdfs_core::proton_sdk::api::{HumanVerification, HumanVerificationCredential};
 
 pub(crate) struct LoginState {
     // Login page.
@@ -9,6 +9,9 @@ pub(crate) struct LoginState {
     /// Spins inside the Sign in button while a sign-in is running.
     pub(crate) login_spinner: Spinner,
     pub(crate) login_status: gtk4::Label,
+    /// Shown over the form while a saved sign-in exists but the keyring would
+    /// not hand it over; see [`keyring_unreadable`].
+    pub(crate) keyring_banner: adw::Banner,
 }
 
 /// Where the login page's account links go.
@@ -87,6 +90,12 @@ pub(crate) fn build_login_page() -> (gtk4::Widget, LoginState) {
         .child(&inner)
         .build();
     let scroll = gtk4::ScrolledWindow::builder().child(&clamp).build();
+    let keyring_banner = adw::Banner::builder()
+        .title(gettext(
+            "Couldn't read your saved sign-in. Unlock the system keyring, then try again.",
+        ))
+        .button_label(gettext("Retry"))
+        .build();
 
     (
         scroll.upcast(),
@@ -96,10 +105,80 @@ pub(crate) fn build_login_page() -> (gtk4::Widget, LoginState) {
             login_button,
             login_spinner,
             login_status,
+            keyring_banner,
         },
     )
 }
 
+/// The stored session, `None` when there is none, or the keyring's error when
+/// it could not be read. A locked or absent keyring is not a sign-out: the
+/// session is still saved, and signing in again would only replace it.
+pub(crate) fn read_session() -> pdfs_core::Result<Option<auth::StoredSession>> {
+    match auth::load() {
+        Ok(session) => Ok(Some(session)),
+        Err(pdfs_core::Error::NotLoggedIn) => Ok(None),
+        Err(e) => Err(e),
+    }
+}
+
+/// How long to wait before each automatic retry of an unreadable keyring. A
+/// keyring daemon started with the session is usually up within seconds.
+const KEYRING_RETRIES: [u32; 4] = [2, 5, 10, 30];
+
+/// The keyring refused to hand over the saved session. Keep the login page up,
+/// but say why, and pick the session up as soon as the keyring answers: on its
+/// own a few times, and whenever the user presses Retry.
+pub(crate) fn keyring_unreadable(ui: &Rc<Ui>, error: &pdfs_core::Error) {
+    tracing::warn!("cannot read the saved session: {error}");
+    let banner = &ui.login.keyring_banner;
+    if banner.is_revealed() {
+        return;
+    }
+    banner.set_revealed(true);
+    let ui_retry = ui.clone();
+    let handler = banner.connect_button_clicked(move |_| retry_session(&ui_retry));
+    // Disconnected once the banner goes, so a later failure wires it afresh.
+    let handler = RefCell::new(Some(handler));
+    banner.connect_revealed_notify(move |banner| {
+        if !banner.is_revealed()
+            && let Some(handler) = handler.borrow_mut().take()
+        {
+            banner.disconnect(handler);
+        }
+    });
+    let ui = ui.clone();
+    glib::spawn_future_local(async move {
+        for seconds in KEYRING_RETRIES {
+            glib::timeout_future_seconds(seconds).await;
+            if !ui.login.keyring_banner.is_revealed() {
+                return;
+            }
+            retry_session(&ui);
+        }
+    });
+}
+
+/// Read the saved session again after [`keyring_unreadable`]. Found: show the
+/// signed-in window. Gone: the plain login page. Still unreadable: keep waiting.
+fn retry_session(ui: &Rc<Ui>) {
+    let ui = ui.clone();
+    glib::spawn_future_local(async move {
+        let Ok(result) = gio::spawn_blocking(read_session).await else {
+            return;
+        };
+        match result {
+            Ok(session) => {
+                ui.login.keyring_banner.set_revealed(false);
+                if session.is_some() && ui.session.borrow().is_none() {
+                    *ui.session.borrow_mut() = session;
+                    refresh(&ui);
+                }
+            }
+            Err(e) => tracing::debug!("the keyring still cannot be read: {e}"),
+        }
+    });
+}
+
 /// Connect the sign-in button: read the fields, run [`auth::login`] on a worker
 /// thread, and report the outcome back on the main loop.
 pub(crate) fn wire_login(ui: &Rc<Ui>) {
@@ -128,7 +207,12 @@ pub(crate) fn wire_login(ui: &Rc<Ui>) {
 
         set_signing_in(&ui, true);
         ui.login.login_status.set_text(&gettext("Signing in…"));
-        let (rx, totp_req_rx, hv_req_rx) = spawn_login(username, password);
+        let LoginChannels {
+            result: rx,
+            totp: totp_req_rx,
+            hv: hv_req_rx,
+            mailbox: mailbox_req_rx,
+        } = spawn_login(username, password);
 
         // Surface the 2FA dialog only if the SDK actually asks for a code (i.e.
         // the account has 2FA enabled). The worker blocks until the dialog feeds
@@ -145,15 +229,40 @@ pub(crate) fn wire_login(ui: &Rc<Ui>) {
         });
 
         // Same shape for human verification: only fires when the API gates the
-        // sign-in, and the worker is blocked on the token until it does.
+        // sign-in, and the worker is blocked on the credential until it does.
         let ui_hv = ui.clone();
         glib::spawn_future_local(async move {
-            if let Ok((url, token_tx)) = hv_req_rx.recv().await {
+            if let Ok((hv, credential_tx)) = hv_req_rx.recv().await {
                 ui_hv
                     .login
                     .login_status
                     .set_text(&gettext("Complete the verification to continue…"));
-                prompt_human_verification(&ui_hv, &url, token_tx);
+                // Anything but a credential drops the sender, which the worker
+                // reads as a cancelled sign-in.
+                match verify_human(hv.verification_url()).await {
+                    Verification::Solved(token) => {
+                        let _ = credential_tx.send(HumanVerificationCredential::captcha(token));
+                    }
+                    Verification::Cancelled => {}
+                    // The web view could not start, most likely its sandbox
+                    // (B195): the user's browser can show the page instead.
+                    Verification::Failed => verify_in_browser(&ui_hv, &hv, credential_tx),
+                }
+            }
+        });
+
+        // And for the mailbox password, which only a two-password account has.
+        // The worker asks again after a wrong answer, so this loops too.
+        let ui_mailbox = ui.clone();
+        glib::spawn_future_local(async move {
+            while let Ok((attempt, answer_tx)) = mailbox_req_rx.recv().await {
+                ask_mailbox(&ui_mailbox, attempt > 0, move |answer| {
+                    // A cancelled dialog drops the sender, which the worker
+                    // reads as a cancelled login.
+                    if let Some(answer) = answer {
+                        let _ = answer_tx.send(answer);
+                    }
+                });
             }
         });
 
@@ -169,7 +278,14 @@ pub(crate) fn wire_login(ui: &Rc<Ui>) {
                     ui.login.login_status.set_text("");
                     ui.login.password.set_text("");
                     // Cache the new identity so `refresh` never hits the keyring.
-                    *ui.session.borrow_mut() = auth::load().ok();
+                    // Read on a worker: a keyring that has to be unlocked first
+                    // answers only once the user has, and the window must not
+                    // freeze until then.
+                    match gio::spawn_blocking(read_session).await {
+                        Ok(Ok(session)) => *ui.session.borrow_mut() = session,
+                        Ok(Err(e)) => keyring_unreadable(&ui, &e),
+                        Err(_) => {}
+                    }
                     // Enable+start the mount service now that we have a session.
                     let _ = gio::spawn_blocking(service::enable_start).await;
                     refresh(&ui);
@@ -197,6 +313,11 @@ pub(crate) fn login_error_message(error: &pdfs_core::Error) -> String {
         pdfs_core::Error::Proton(ProtonError::Api(api)) if api.http_status == 429 => {
             gettext("Too many sign-in attempts. Wait a few minutes and try again.")
         }
+        // Proton's text for this one asks the user to update an app that is
+        // already current.
+        pdfs_core::Error::Proton(e) if pdfs_core::error::sign_in_blocked(e) => gettext(
+            "Proton is temporarily refusing sign-in from this device. Your app version is not the problem. Wait several hours, up to a day, without trying again, then sign in.",
+        ),
         pdfs_core::Error::Proton(ProtonError::Api(api)) if !api.message.is_empty() => {
             api.message.clone()
         }
@@ -209,6 +330,12 @@ pub(crate) fn login_error_message(error: &pdfs_core::Error) -> String {
         pdfs_core::Error::Other(message) if message.contains("two-factor") => {
             gettext("Sign-in cancelled: no two-factor code was entered.")
         }
+        pdfs_core::Error::Other(message) if message.contains("mailbox") => {
+            gettext("Sign-in cancelled: no mailbox password was entered.")
+        }
+        pdfs_core::Error::WrongMailboxPassword => {
+            gettext("That mailbox password didn't unlock your account.")
+        }
         pdfs_core::Error::Other(message) if message.contains("verification") => gettext(
             "Sign-in cancelled: the verification wasn't completed. Sign in again to get a new one.",
         ),
@@ -220,26 +347,34 @@ pub(crate) fn login_error_message(error: &pdfs_core::Error) -> String {
     }
 }
 
+/// What the login worker asks the UI for, and how it reports back.
+pub(crate) struct LoginChannels {
+    /// The final outcome, once.
+    pub(crate) result: async_channel::Receiver<Result<(), String>>,
+    /// Fires only if the account needs a 2FA code; carries the sender for it.
+    pub(crate) totp: async_channel::Receiver<std::sync::mpsc::Sender<String>>,
+    /// Fires only if the sign-in is gated: the challenge, and the sender for the
+    /// credential the user earns by solving it.
+    pub(crate) hv: async_channel::Receiver<(
+        HumanVerification,
+        std::sync::mpsc::Sender<HumanVerificationCredential>,
+    )>,
+    /// Fires only for a two-password account: how many answers were already
+    /// wrong, and the sender for the password and the "remember" choice.
+    pub(crate) mailbox: async_channel::Receiver<(u32, std::sync::mpsc::Sender<(String, bool)>)>,
+}
+
 /// Run the async SRP + optional 2FA login on a dedicated current-thread Tokio
-/// runtime. Returns two channels: the first yields the final login result once;
-/// the second fires *only if* the account needs a 2FA code, carrying a
-/// [`std::sync::mpsc::Sender`] the UI uses to feed the code back. The login
-/// closure blocks the worker on that sender until the dialog answers, so the
-/// code is requested lazily and can't expire before the password proof.
-#[allow(clippy::type_complexity)]
-pub(crate) fn spawn_login(
-    username: String,
-    password: String,
-) -> (
-    async_channel::Receiver<Result<(), String>>,
-    async_channel::Receiver<std::sync::mpsc::Sender<String>>,
-    async_channel::Receiver<(String, std::sync::mpsc::Sender<String>)>,
-) {
+/// runtime. The returned [`LoginChannels`] carry the final result and the lazy
+/// prompts. Each login closure blocks the worker on a sender the UI answers, so
+/// a code is requested lazily and can't expire before the password proof.
+pub(crate) fn spawn_login(username: String, password: String) -> LoginChannels {
     let (tx, rx) = async_channel::bounded(1);
     // Two, not one: a CAPTCHA-gated login restarts, so a 2FA account is asked
     // for a code on each attempt and a single slot would deadlock the worker.
     let (totp_req_tx, totp_req_rx) = async_channel::bounded(2);
     let (hv_req_tx, hv_req_rx) = async_channel::bounded(1);
+    let (mailbox_req_tx, mailbox_req_rx) = async_channel::bounded(1);
     std::thread::spawn(move || {
         let rt = match tokio::runtime::Builder::new_current_thread()
             .enable_all()
@@ -267,19 +402,30 @@ pub(crate) fn spawn_login(
                         .recv()
                         .map_err(|_| pdfs_core::Error::Other("two-factor entry cancelled".into()))
                 },
-                |hv| {
-                    // Gated: hand the UI the page to show, block on the token the
-                    // user earns by solving it.
-                    let (token_tx, token_rx) = std::sync::mpsc::channel::<String>();
-                    hv_req_tx
-                        .send_blocking((hv.verification_url(), token_tx))
-                        .map_err(|_| {
-                            pdfs_core::Error::Other("verification prompt closed".into())
-                        })?;
-                    let token = token_rx
+                |attempt| {
+                    let (answer_tx, answer_rx) = std::sync::mpsc::channel::<(String, bool)>();
+                    mailbox_req_tx
+                        .send_blocking((attempt, answer_tx))
+                        .map_err(|_| pdfs_core::Error::Other("mailbox prompt closed".into()))?;
+                    let (password, remember) = answer_rx
                         .recv()
-                        .map_err(|_| pdfs_core::Error::Other("verification cancelled".into()))?;
-                    Ok(HumanVerificationCredential::captcha(token))
+                        .map_err(|_| pdfs_core::Error::Other("mailbox entry cancelled".into()))?;
+                    Ok(auth::Mailbox {
+                        password: password.into(),
+                        remember,
+                    })
+                },
+                |hv| {
+                    // Gated: hand the UI the challenge, block on the credential
+                    // the user earns by solving it.
+                    let (credential_tx, credential_rx) =
+                        std::sync::mpsc::channel::<HumanVerificationCredential>();
+                    hv_req_tx.send_blocking((hv, credential_tx)).map_err(|_| {
+                        pdfs_core::Error::Other("verification prompt closed".into())
+                    })?;
+                    credential_rx
+                        .recv()
+                        .map_err(|_| pdfs_core::Error::Other("verification cancelled".into()))
                 },
             )
             .await
@@ -287,7 +433,143 @@ pub(crate) fn spawn_login(
         });
         let _ = tx.send_blocking(result);
     });
-    (rx, totp_req_rx, hv_req_rx)
+    LoginChannels {
+        result: rx,
+        totp: totp_req_rx,
+        hv: hv_req_rx,
+        mailbox: mailbox_req_rx,
+    }
+}
+
+/// Ask for the mailbox password of a two-password account.
+///
+/// `done` gets the password and the "keep unlocked" choice, or `None` when the
+/// dialog was cancelled. `retry` says the last answer was wrong. The choice
+/// defaults to off: storing the mailbox unlock in the keyring trades away what
+/// a separate mailbox password is for, so it is something to opt into.
+pub(crate) fn ask_mailbox(
+    ui: &Rc<Ui>,
+    retry: bool,
+    done: impl FnOnce(Option<(String, bool)>) + 'static,
+) {
+    let body = if retry {
+        gettext("That mailbox password didn't unlock your account. Try again.")
+    } else {
+        gettext("This account has a separate mailbox password. Enter it to unlock your files.")
+    };
+    let dialog = adw::AlertDialog::builder()
+        .heading(gettext("Mailbox Password"))
+        .body(body)
+        .build();
+
+    let group = adw::PreferencesGroup::new();
+    let entry = adw::PasswordEntryRow::builder()
+        .title(gettext("Mailbox password"))
+        .activates_default(true)
+        .build();
+    let remember = adw::SwitchRow::builder()
+        .title(gettext("Keep unlocked on this computer"))
+        .subtitle(gettext(
+            "Stores the unlock in the system keyring, so Proton Drive opens without asking after every login. Otherwise you enter the password once per session.",
+        ))
+        .build();
+    group.add(&entry);
+    group.add(&remember);
+    dialog.set_extra_child(Some(&group));
+
+    dialog.add_response("cancel", &gettext("Cancel"));
+    dialog.add_response("unlock", &gettext("Unlock"));
+    dialog.set_response_appearance("unlock", adw::ResponseAppearance::Suggested);
+    dialog.set_default_response(Some("unlock"));
+    dialog.set_close_response("cancel");
+
+    let done = RefCell::new(Some(done));
+    dialog.connect_response(None, move |_, resp| {
+        let Some(done) = done.borrow_mut().take() else {
+            return;
+        };
+        let password = entry.text().to_string();
+        if resp == "unlock" && !password.is_empty() {
+            done(Some((password, remember.is_active())));
+        } else {
+            done(None);
+        }
+    });
+
+    let parent = ui_window(ui).map(|w| w.upcast::<gtk4::Window>());
+    dialog.present(parent.as_ref());
+}
+
+/// If the signed-in account is locked, ask for its mailbox password — once per
+/// run; after a cancel, a toast keeps an Unlock button within reach.
+///
+/// The key state is a keyring and kernel-keyring read, so it runs on a worker.
+pub(crate) fn offer_unlock(ui: &Rc<Ui>) {
+    if ui.unlock_offered.get() {
+        return;
+    }
+    let ui = ui.clone();
+    glib::spawn_future_local(async move {
+        let state = gio::spawn_blocking(|| auth::key_state().ok()).await;
+        if matches!(state, Ok(Some(auth::KeyState::Locked))) && !ui.unlock_offered.replace(true) {
+            prompt_unlock(&ui, false);
+        }
+    });
+}
+
+enum UnlockOutcome {
+    Unlocked,
+    Wrong,
+    Failed(String),
+}
+
+/// Ask for the mailbox password and unlock the account with it.
+fn prompt_unlock(ui: &Rc<Ui>, retry: bool) {
+    let ui_done = ui.clone();
+    ask_mailbox(ui, retry, move |answer| {
+        let Some((password, remember)) = answer else {
+            toast_action(
+                &ui_done,
+                &gettext("Proton Drive is locked. Enter your mailbox password to unlock it."),
+                &gettext("Unlock"),
+                |ui| prompt_unlock(ui, false),
+            );
+            return;
+        };
+        glib::spawn_future_local(async move {
+            // Verifying talks to Proton and the restart talks to systemd, so
+            // both run on a worker, never on the main loop.
+            let outcome = gio::spawn_blocking(move || {
+                let rt = match tokio::runtime::Builder::new_current_thread()
+                    .enable_all()
+                    .build()
+                {
+                    Ok(rt) => rt,
+                    Err(e) => return UnlockOutcome::Failed(e.to_string()),
+                };
+                match rt.block_on(auth::unlock(&password, remember)) {
+                    Ok(()) => {
+                        service::restart();
+                        UnlockOutcome::Unlocked
+                    }
+                    Err(pdfs_core::Error::WrongMailboxPassword) => UnlockOutcome::Wrong,
+                    Err(e) => UnlockOutcome::Failed(login_error_message(&e)),
+                }
+            })
+            .await;
+            match outcome {
+                Ok(UnlockOutcome::Unlocked) => {
+                    toast(&ui_done, &gettext("Unlocked."));
+                    refresh(&ui_done);
+                }
+                Ok(UnlockOutcome::Wrong) => prompt_unlock(&ui_done, true),
+                Ok(UnlockOutcome::Failed(message)) => {
+                    toast_error(&ui_done, &gettext("Couldn't unlock"), &message)
+                }
+                Err(_) => {}
+            }
+        });
+    });
 }
 
 /// Show the lazy two-factor dialog and feed the entered code back to the waiting
@@ -330,6 +612,63 @@ pub(crate) fn prompt_2fa(ui: &Rc<Ui>, code_tx: std::sync::mpsc::Sender<String>)
     dialog.present(parent.as_ref());
 }
 
+/// Let the user solve the challenge in their own browser, for when the
+/// verification window could not come up. The page cannot hand its token back
+/// to us, so the user says when they are done, and the retry carries the
+/// challenge token, which the solved page made good (see
+/// [`auth::browser_verified`]).
+fn verify_in_browser(
+    ui: &Rc<Ui>,
+    hv: &HumanVerification,
+    credential_tx: std::sync::mpsc::Sender<HumanVerificationCredential>,
+) {
+    let dialog = adw::AlertDialog::builder()
+        .heading(gettext("Verify in Your Browser"))
+        .body(gettext(
+            "The verification page can't be shown in the app on this system. Open it in your browser, complete it there, then come back and choose Continue.",
+        ))
+        .build();
+
+    let url = auth::browser_verification_url(hv);
+    let open = gtk4::Button::builder()
+        .label(gettext("Open Verification Page"))
+        .halign(gtk4::Align::Center)
+        .build();
+    open.add_css_class("pill");
+    dialog.set_extra_child(Some(&open));
+
+    dialog.add_response("cancel", &gettext("Cancel"));
+    dialog.add_response("continue", &gettext("Continue"));
+    dialog.set_response_appearance("continue", adw::ResponseAppearance::Suggested);
+    // Continuing before the page was even opened would only fail the retry.
+    dialog.set_response_enabled("continue", false);
+    dialog.set_default_response(Some("continue"));
+    dialog.set_close_response("cancel");
+
+    let dialog_weak = dialog.downgrade();
+    open.connect_clicked(move |_| {
+        open_uri(&url);
+        if let Some(dialog) = dialog_weak.upgrade() {
+            dialog.set_response_enabled("continue", true);
+        }
+    });
+
+    let credential = auth::browser_verified(hv);
+    let credential_tx = RefCell::new(Some(credential_tx));
+    dialog.connect_response(None, move |_, resp| {
+        // On cancel/close we take + drop `tx` without sending, so the worker's
+        // recv errors out and the login is reported as cancelled.
+        if let Some(tx) = credential_tx.borrow_mut().take()
+            && resp == "continue"
+        {
+            let _ = tx.send(credential.clone());
+        }
+    });
+
+    let parent = ui.login.login_button.root().and_downcast::<gtk4::Window>();
+    dialog.present(parent.as_ref());
+}
+
 /// Sign out, after a confirmation: disable+stop the mount service (so the
 /// daemon isn't left running without credentials), forget the stored session,
 /// and drop back to the login page.
@@ -349,7 +688,7 @@ pub(crate) fn sign_out(ui: &Rc<Ui>) {
             glib::spawn_future_local(async move {
                 let result = gio::spawn_blocking(|| {
                     service::disable_stop();
-                    auth::logout().map_err(|e| e.to_string())
+                    auth::logout().map(|_| ()).map_err(|e| e.to_string())
                 })
                 .await;
                 if let Ok(Err(e)) = result {
@@ -374,6 +713,27 @@ mod tests {
         assert!(login_error_message(&hv).contains("verification wasn't completed"));
     }
 
+    #[test]
+    fn a_cancelled_mailbox_prompt_is_reported_as_such() {
+        let error = pdfs_core::Error::Other("mailbox entry cancelled".into());
+        assert!(login_error_message(&error).contains("no mailbox password"));
+    }
+
+    #[test]
+    fn a_blocked_sign_in_does_not_ask_for_an_update() {
+        use pdfs_core::proton_sdk::api::ResponseCode;
+        use pdfs_core::proton_sdk::{ProtonApiError, ProtonError};
+        let error = pdfs_core::Error::Proton(ProtonError::Api(ProtonApiError {
+            code: ResponseCode::Blocked,
+            http_status: 422,
+            message: "This version of the app is no longer supported, please update to continue using the app".into(),
+            details: None,
+        }));
+        let message = login_error_message(&error);
+        assert!(message.contains("temporarily refusing"), "{message}");
+        assert!(!message.contains("update"), "{message}");
+    }
+
     #[test]
     fn an_unmapped_error_keeps_its_text() {
         let error = pdfs_core::Error::Other("something odd".into());

crates/pdfs-gui/src/app/pages/photo_viewer.rs

@@ -275,14 +275,42 @@ pub(crate) fn load_photo(ui: &Rc<Ui>, viewer: &Rc<Viewer>, uid: String) {
             viewer.status.set_label(message);
             viewer.status.set_visible(true);
         };
-        match result {
-            Ok(Ok(Response::FilePath { path })) if is_video => {
+        let path = match result {
+            Ok(Ok(Response::FilePath { path })) => path,
+            Ok(Ok(Response::Error { message, .. })) => return fail(&message),
+            Ok(Ok(_)) => return fail(&gettext("Unexpected reply from the Proton Drive service.")),
+            Ok(Err(_)) | Err(_) => return fail(&gettext("Couldn't reach Proton Drive.")),
+        };
+        // Decoding a full-size photo and reading its EXIF take a good part of
+        // a second for a large one, which froze the whole app on the main
+        // thread. Done on a worker; a reply for a photo the user has since
+        // left is dropped like the request's own.
+        let loaded = {
+            let path = path.clone();
+            gio::spawn_blocking(move || {
+                let size = std::fs::metadata(&path).ok().map(|meta| meta.len());
+                if is_video {
+                    return (size, None, ExifInfo::default());
+                }
+                let texture = gtk4::gdk::Texture::from_filename(&path);
+                (size, Some(texture), read_exif(&path))
+            })
+            .await
+        };
+        if *viewer.uid.borrow() != uid {
+            return;
+        }
+        let Ok((size, texture, info)) = loaded else {
+            return fail(&gettext("Couldn't render this photo."));
+        };
+        match texture {
+            None => {
                 viewer.video.set_filename(Some(&path));
                 viewer.media.set_visible_child_name("video");
                 *viewer.path.borrow_mut() = Some(path.clone());
-                show_info(&viewer, &path, ExifInfo::default());
+                show_info(&viewer, size, ExifInfo::default());
             }
-            Ok(Ok(Response::FilePath { path })) => match gtk4::gdk::Texture::from_filename(&path) {
+            Some(texture) => match texture {
                 Ok(texture) => {
                     // Zoomed in on the thumbnail: keep the photo the size it is
                     // on screen, now drawn from the full-size pixels.
@@ -297,16 +325,13 @@ pub(crate) fn load_photo(ui: &Rc<Ui>, viewer: &Rc<Viewer>, uid: String) {
                         zoom_to(&viewer, Some(zoom), None);
                     }
                     *viewer.path.borrow_mut() = Some(path.clone());
-                    show_info(&viewer, &path, read_exif(&path));
+                    show_info(&viewer, size, info);
                 }
                 Err(e) => {
                     tracing::error!("Failed to load texture for {path}: {e}");
                     fail(&gettext("Couldn't render this photo."));
                 }
             },
-            Ok(Ok(Response::Error { message, .. })) => fail(&message),
-            Ok(Ok(_)) => fail(&gettext("Unexpected reply from the Proton Drive service.")),
-            Ok(Err(_)) | Err(_) => fail(&gettext("Couldn't reach Proton Drive.")),
         }
     });
 }
@@ -452,16 +477,16 @@ pub(crate) fn clear_info(viewer: &Rc<Viewer>) {
 }
 
 /// Fill the details drawer for the photo now on screen: its own file facts
-/// (size, dimensions) plus whatever EXIF it carries.
-pub(crate) fn show_info(viewer: &Rc<Viewer>, path: &str, info: ExifInfo) {
+/// (`size`, dimensions) plus whatever EXIF it carries.
+pub(crate) fn show_info(viewer: &Rc<Viewer>, size: Option<u64>, info: ExifInfo) {
     while let Some(row) = viewer.info_rows.first_child() {
         viewer.info_rows.remove(&row);
     }
 
     let mut fields: Vec<(String, String)> = Vec::new();
-    if let Ok(meta) = std::fs::metadata(path) {
+    if let Some(size) = size {
         // Translators: label of a photo's file size in the details panel.
-        fields.push((pgettext("property", "Size"), human_bytes(meta.len())));
+        fields.push((pgettext("property", "Size"), human_bytes(size)));
     }
     fields.extend(info.fields);
 
@@ -481,6 +506,7 @@ pub(crate) fn show_info(viewer: &Rc<Viewer>, path: &str, info: ExifInfo) {
             let row = adw::ActionRow::builder()
                 .title(label.as_str())
                 .subtitle(value)
+                .use_markup(false)
                 .subtitle_selectable(true)
                 .build();
             row.add_css_class("property");
@@ -1259,8 +1285,11 @@ pub(crate) fn open_photo_viewer(ui: &Rc<Ui>, initial_uid: String) {
     // Any real pointer movement brings the controls back; resting over one of
     // them keeps them up.
     let motion = gtk4::EventControllerMotion::new();
-    let viewer_motion = viewer.clone();
+    let viewer_motion = Rc::downgrade(&viewer);
     motion.connect_motion(move |_, x, y| {
+        let Some(viewer_motion) = viewer_motion.upgrade() else {
+            return;
+        };
         let (last_x, last_y) = viewer_motion.pointer.get();
         viewer_motion.pointer.set((x, y));
         if (x - last_x).abs() > 1.0 || (y - last_y).abs() > 1.0 {
@@ -1270,10 +1299,17 @@ pub(crate) fn open_photo_viewer(ui: &Rc<Ui>, initial_uid: String) {
     body.add_controller(motion);
     for revealer in [&top_reveal, &prev_reveal, &next_reveal] {
         let hover = gtk4::EventControllerMotion::new();
-        let viewer_enter = viewer.clone();
-        hover.connect_enter(move |_, _, _| viewer_enter.chrome_hover.set(true));
-        let viewer_leave = viewer.clone();
+        let viewer_enter = Rc::downgrade(&viewer);
+        hover.connect_enter(move |_, _, _| {
+            if let Some(viewer) = viewer_enter.upgrade() {
+                viewer.chrome_hover.set(true);
+            }
+        });
+        let viewer_leave = Rc::downgrade(&viewer);
         hover.connect_leave(move |_| {
+            let Some(viewer_leave) = viewer_leave.upgrade() else {
+                return;
+            };
             viewer_leave.chrome_hover.set(false);
             show_chrome(&viewer_leave);
         });
@@ -1283,8 +1319,11 @@ pub(crate) fn open_photo_viewer(ui: &Rc<Ui>, initial_uid: String) {
     // Ctrl+scroll zooms around the pointer; a plain scroll pans a zoomed photo.
     let wheel = gtk4::EventControllerScroll::new(gtk4::EventControllerScrollFlags::VERTICAL);
     wheel.set_propagation_phase(gtk4::PropagationPhase::Capture);
-    let viewer_wheel = viewer.clone();
+    let viewer_wheel = Rc::downgrade(&viewer);
     wheel.connect_scroll(move |controller, _, dy| {
+        let Some(viewer_wheel) = viewer_wheel.upgrade() else {
+            return glib::Propagation::Proceed;
+        };
         if !controller
             .current_event_state()
             .contains(gtk4::gdk::ModifierType::CONTROL_MASK)
@@ -1304,14 +1343,20 @@ pub(crate) fn open_photo_viewer(ui: &Rc<Ui>, initial_uid: String) {
     scroller.add_controller(wheel);
 
     let pinch = gtk4::GestureZoom::new();
-    let viewer_pinch = viewer.clone();
+    let viewer_pinch = Rc::downgrade(&viewer);
     pinch.connect_begin(move |_, _| {
+        let Some(viewer_pinch) = viewer_pinch.upgrade() else {
+            return;
+        };
         viewer_pinch
             .pinch_start
             .set(current_scale(&viewer_pinch).unwrap_or(1.0));
     });
-    let viewer_pinch = viewer.clone();
+    let viewer_pinch = Rc::downgrade(&viewer);
     pinch.connect_scale_changed(move |gesture, delta| {
+        let Some(viewer_pinch) = viewer_pinch.upgrade() else {
+            return;
+        };
         let start = viewer_pinch.pinch_start.get();
         zoom_to(
             &viewer_pinch,
@@ -1323,8 +1368,11 @@ pub(crate) fn open_photo_viewer(ui: &Rc<Ui>, initial_uid: String) {
 
     // Dragging a zoomed photo pans it.
     let drag = gtk4::GestureDrag::new();
-    let viewer_drag = viewer.clone();
+    let viewer_drag = Rc::downgrade(&viewer);
     drag.connect_drag_begin(move |_, _, _| {
+        let Some(viewer_drag) = viewer_drag.upgrade() else {
+            return;
+        };
         let scroller = &viewer_drag.scroller;
         viewer_drag.drag_start.set((
             scroller.hadjustment().value(),
@@ -1334,8 +1382,11 @@ pub(crate) fn open_photo_viewer(ui: &Rc<Ui>, initial_uid: String) {
             viewer_drag.picture.set_cursor_from_name(Some("grabbing"));
         }
     });
-    let viewer_drag = viewer.clone();
+    let viewer_drag = Rc::downgrade(&viewer);
     drag.connect_drag_update(move |_, dx, dy| {
+        let Some(viewer_drag) = viewer_drag.upgrade() else {
+            return;
+        };
         if viewer_drag.zoom.get().is_none() {
             return;
         }
@@ -1343,39 +1394,58 @@ pub(crate) fn open_photo_viewer(ui: &Rc<Ui>, initial_uid: String) {
         viewer_drag.scroller.hadjustment().set_value(x - dx);
         viewer_drag.scroller.vadjustment().set_value(y - dy);
     });
-    let viewer_drag = viewer.clone();
+    let viewer_drag = Rc::downgrade(&viewer);
     drag.connect_drag_end(move |_, _, _| {
+        let Some(viewer_drag) = viewer_drag.upgrade() else {
+            return;
+        };
         if viewer_drag.zoom.get().is_some() {
             viewer_drag.picture.set_cursor_from_name(Some("grab"));
         }
     });
     scroller.add_controller(drag);
 
-    let w_close = window.clone();
+    let w_close = window.downgrade();
     close_btn.connect_clicked(move |_| {
+        let Some(w_close) = w_close.upgrade() else {
+            return;
+        };
         w_close.close();
     });
 
-    let viewer_closing = viewer.clone();
+    // The one strong handle on the viewer. Every handler holds a weak one: a
+    // strong one in a handler of a widget the viewer holds is a cycle, which
+    // kept every closed lightbox, its window and its full-size photo in memory
+    // for the life of the app.
+    let keep = RefCell::new(Some(viewer.clone()));
     window.connect_close_request(move |_| {
-        stop_video(&viewer_closing);
-        disarm_slide(&viewer_closing);
-        if let Some(source) = viewer_closing.chrome_source.borrow_mut().take() {
-            source.remove();
+        if let Some(viewer) = keep.borrow_mut().take() {
+            stop_video(&viewer);
+            disarm_slide(&viewer);
+            if let Some(source) = viewer.chrome_source.borrow_mut().take() {
+                source.remove();
+            }
+            viewer.picture.set_paintable(gtk4::gdk::Paintable::NONE);
         }
         glib::Propagation::Proceed
     });
 
-    let viewer_info = viewer.clone();
+    let viewer_info = Rc::downgrade(&viewer);
     info_toggle.connect_toggled(move |toggle| {
+        let Some(viewer_info) = viewer_info.upgrade() else {
+            return;
+        };
         viewer_info
             .info_revealer
             .set_reveal_child(toggle.is_active());
     });
 
     let ui_slides = ui.clone();
-    let viewer_slides = viewer.clone();
+    let viewer_slides = Rc::downgrade(&viewer);
     slideshow_btn.connect_toggled(move |toggle| {
+        let Some(viewer_slides) = viewer_slides.upgrade() else {
+            return;
+        };
         if toggle.is_active() {
             start_slideshow(&ui_slides, &viewer_slides);
         } else {
@@ -1387,9 +1457,15 @@ pub(crate) fn open_photo_viewer(ui: &Rc<Ui>, initial_uid: String) {
     info_close.connect_clicked(move |_| toggle_off.set_active(false));
 
     let ui_map = ui.clone();
-    let viewer_map = viewer.clone();
-    let w_map = window.clone();
+    let viewer_map = Rc::downgrade(&viewer);
+    let w_map = window.downgrade();
     info_map.connect_clicked(move |_| {
+        let Some(w_map) = w_map.upgrade() else {
+            return;
+        };
+        let Some(viewer_map) = viewer_map.upgrade() else {
+            return;
+        };
         let coords = *viewer_map.coords.borrow();
         if let Some((lat, lon)) = coords {
             w_map.close();
@@ -1398,8 +1474,11 @@ pub(crate) fn open_photo_viewer(ui: &Rc<Ui>, initial_uid: String) {
     });
 
     let ui_fav = ui.clone();
-    let viewer_fav = viewer.clone();
+    let viewer_fav = Rc::downgrade(&viewer);
     favorite_btn.connect_toggled(move |btn| {
+        let Some(viewer_fav) = viewer_fav.upgrade() else {
+            return;
+        };
         if viewer_fav.favorite_suppress.get() {
             return;
         }
@@ -1443,17 +1522,26 @@ pub(crate) fn open_photo_viewer(ui: &Rc<Ui>, initial_uid: String) {
     // gone, and leaving it open on a trashed photo invites a second Delete on
     // something the user cannot see.
     let ui_delete = ui.clone();
-    let viewer_delete = viewer.clone();
-    let w_delete = window.clone();
+    let viewer_delete = Rc::downgrade(&viewer);
+    let w_delete = window.downgrade();
     delete_btn.connect_clicked(move |_| {
+        let Some(w_delete) = w_delete.upgrade() else {
+            return;
+        };
+        let Some(viewer_delete) = viewer_delete.upgrade() else {
+            return;
+        };
         let uid = viewer_delete.uid.borrow().clone();
         w_delete.close();
         trash_photos(&ui_delete, vec![uid], false);
     });
 
     let ui_group = ui.clone();
-    let viewer_group = viewer.clone();
+    let viewer_group = Rc::downgrade(&viewer);
     group_btn.connect_clicked(move |_| {
+        let Some(viewer_group) = viewer_group.upgrade() else {
+            return;
+        };
         let uid = viewer_group.uid.borrow().clone();
         let next =
             next_group_member(&viewer_group.group.borrow(), &uid).map(|item| item.uid.clone());
@@ -1464,9 +1552,15 @@ pub(crate) fn open_photo_viewer(ui: &Rc<Ui>, initial_uid: String) {
     });
 
     let ui_download = ui.clone();
-    let w_download = window.clone();
-    let viewer_download = viewer.clone();
+    let w_download = window.downgrade();
+    let viewer_download = Rc::downgrade(&viewer);
     download_btn.connect_clicked(move |_| {
+        let Some(w_download) = w_download.upgrade() else {
+            return;
+        };
+        let Some(viewer_download) = viewer_download.upgrade() else {
+            return;
+        };
         if let Some(path) = viewer_download.path.borrow().as_deref() {
             let name = viewer_download.name.borrow();
             save_photo_to_disk(
@@ -1478,23 +1572,35 @@ pub(crate) fn open_photo_viewer(ui: &Rc<Ui>, initial_uid: String) {
         }
     });
 
-    let w_ext = window.clone();
-    let viewer_ext = viewer.clone();
+    let w_ext = window.downgrade();
+    let viewer_ext = Rc::downgrade(&viewer);
     open_ext_btn.connect_clicked(move |_| {
+        let Some(w_ext) = w_ext.upgrade() else {
+            return;
+        };
+        let Some(viewer_ext) = viewer_ext.upgrade() else {
+            return;
+        };
         if let Some(path) = viewer_ext.path.borrow().as_deref() {
             open_with(&w_ext, path, viewer_ext.name.borrow().as_deref());
         }
     });
 
     let ui_prev = ui.clone();
-    let viewer_prev = viewer.clone();
+    let viewer_prev = Rc::downgrade(&viewer);
     prev_btn.connect_clicked(move |_| {
+        let Some(viewer_prev) = viewer_prev.upgrade() else {
+            return;
+        };
         navigate_photo(&ui_prev, &viewer_prev, -1);
     });
 
     let ui_next = ui.clone();
-    let viewer_next = viewer.clone();
+    let viewer_next = Rc::downgrade(&viewer);
     next_btn.connect_clicked(move |_| {
+        let Some(viewer_next) = viewer_next.upgrade() else {
+            return;
+        };
         navigate_photo(&ui_next, &viewer_next, 1);
     });
 
@@ -1503,8 +1609,11 @@ pub(crate) fn open_photo_viewer(ui: &Rc<Ui>, initial_uid: String) {
     // reaching for the image doesn't fling the window shut; a zoomed photo has
     // no backdrop to speak of. Double-click toggles between fitted and 100 %.
     let backdrop = gtk4::GestureClick::new();
-    let viewer_click = viewer.clone();
+    let viewer_click = Rc::downgrade(&viewer);
     backdrop.connect_pressed(move |_, n_press, x, y| {
+        let Some(viewer_click) = viewer_click.upgrade() else {
+            return;
+        };
         if n_press != 2 {
             return;
         }
@@ -1521,9 +1630,15 @@ pub(crate) fn open_photo_viewer(ui: &Rc<Ui>, initial_uid: String) {
             zoom_to(&viewer_click, Some((fit * 2.0).max(1.0)), Some(anchor));
         }
     });
-    let viewer_click = viewer.clone();
-    let w_click = window.clone();
+    let viewer_click = Rc::downgrade(&viewer);
+    let w_click = window.downgrade();
     backdrop.connect_released(move |_, n_press, x, y| {
+        let Some(w_click) = w_click.upgrade() else {
+            return;
+        };
+        let Some(viewer_click) = viewer_click.upgrade() else {
+            return;
+        };
         if n_press == 1
             && viewer_click.zoom.get().is_none()
             && !over_photo(&viewer_click.picture, x, y)
@@ -1535,9 +1650,15 @@ pub(crate) fn open_photo_viewer(ui: &Rc<Ui>, initial_uid: String) {
 
     let key_controller = gtk4::EventControllerKey::new();
     let ui_key = ui.clone();
-    let viewer_key = viewer.clone();
-    let w_key = window.clone();
+    let viewer_key = Rc::downgrade(&viewer);
+    let w_key = window.downgrade();
     key_controller.connect_key_pressed(move |_, key, _keycode, state| {
+        let Some(w_key) = w_key.upgrade() else {
+            return glib::Propagation::Proceed;
+        };
+        let Some(viewer_key) = viewer_key.upgrade() else {
+            return glib::Propagation::Proceed;
+        };
         let ctrl = state.contains(gtk4::gdk::ModifierType::CONTROL_MASK);
         let playing_video = viewer_key.media.visible_child_name().as_deref() == Some("video");
         match key.name().as_deref() {

crates/pdfs-gui/src/app/pages/photos.rs

@@ -140,6 +140,9 @@ pub(crate) struct GalleryState {
     pub(crate) loading: Cell<bool>,
     /// Whether the last page came back full, so there may be more to load.
     pub(crate) has_more: Cell<bool>,
+    /// Whether the account has a photo library. Until the daemon says it has
+    /// none, assume it does, so Upload is not greyed out while the page loads.
+    pub(crate) library: Cell<bool>,
     /// Run once the page in flight has landed in [`Self::model`] — how the
     /// lightbox steps past the last loaded photo.
     pub(crate) page_waiters: RefCell<Vec<Box<dyn FnOnce()>>>,
@@ -606,7 +609,7 @@ pub(crate) fn build_gallery_page() -> (gtk4::Widget, GalleryWidgets) {
     select_box.append(&select_done);
     let select_bar = gtk4::Revealer::builder()
         .transition_type(gtk4::RevealerTransitionType::SlideDown)
-        .child(&select_box)
+        .child(&scroll_sideways(&select_box))
         .build();
 
     // All / Photos / Videos / Raw filter. Linked toggles acting as one segmented
@@ -1376,11 +1379,9 @@ pub(crate) fn wire_gallery(
                     "tiff" | "tif" => "image/tiff",
                     _ => "image/jpeg",
                 };
-                let capture_time = std::fs::metadata(&path)
-                    .and_then(|m| m.modified())
-                    .ok()
-                    .and_then(|t| t.duration_since(std::time::SystemTime::UNIX_EPOCH).ok())
-                    .map(|d| d.as_secs() as i64);
+                // The daemon dates the photo: by its EXIF, or by the file's
+                // modification time when it has none.
+                let capture_time = None;
 
                 ui.busy_begin();
                 let rx = spawn_request(
@@ -3341,6 +3342,12 @@ pub(crate) fn load_gallery(ui: &Rc<Ui>, append: bool) {
                 items,
                 counts,
             })) => {
+                // Nothing can go into a library the account does not have; the
+                // SDK refuses the upload before sending it (issue #38).
+                ui.gallery.library.set(available);
+                ui.gallery
+                    .upload
+                    .set_sensitive(available && *ui.mounted.borrow());
                 if !available {
                     gallery_status(
                         &ui,
@@ -3450,7 +3457,9 @@ pub(crate) fn load_gallery(ui: &Rc<Ui>, append: bool) {
 pub(crate) fn gallery_status(ui: &Rc<Ui>, icon: &str, title: &str, description: &str, retry: bool) {
     ui.gallery.status.set_icon_name(Some(icon));
     ui.gallery.status.set_title(title);
-    ui.gallery.status.set_description(Some(description));
+    ui.gallery
+        .status
+        .set_description(Some(&gtk4::glib::markup_escape_text(description)));
     ui.gallery.retry.set_visible(retry);
     // Only the empty timeline offers a way to fill it; every other status turns
     // those buttons back off.
@@ -3470,10 +3479,10 @@ pub(crate) fn gallery_unreachable(ui: &Rc<Ui>) {
 /// right tool for the HEVC `.mkv`s this is aimed at — and falls back to the
 /// user's default handler when mpv isn't installed.
 pub(crate) fn play_external(path: &str) {
-    if Command::new("mpv").arg(path).spawn().is_ok() {
-        return;
+    match Command::new("mpv").arg(path).spawn() {
+        Ok(child) => pdfs_core::opener::reap(child),
+        Err(_) => open_path(path),
     }
-    open_path(path);
 }
 
 #[cfg(test)]

crates/pdfs-gui/src/app/pages/places.rs

@@ -448,7 +448,9 @@ pub(crate) fn close_place(ui: &Rc<Ui>) {
 fn places_status(ui: &Rc<Ui>, icon: &str, title: &str, description: &str) {
     ui.gallery.places_status.set_icon_name(Some(icon));
     ui.gallery.places_status.set_title(title);
-    ui.gallery.places_status.set_description(Some(description));
+    ui.gallery
+        .places_status
+        .set_description(Some(&gtk4::glib::markup_escape_text(description)));
     ui.gallery.places_stack.set_visible_child_name("status");
 }
 

crates/pdfs-gui/src/app/pages/shared.rs

@@ -311,7 +311,9 @@ pub(crate) fn wire_shared(ui: &Rc<Ui>, widgets: &SharedWidgets) {
 pub(crate) fn shared_status(ui: &Rc<Ui>, icon: &str, title: &str, description: &str, retry: bool) {
     ui.shared.status.set_icon_name(Some(icon));
     ui.shared.status.set_title(title);
-    ui.shared.status.set_description(Some(description));
+    ui.shared
+        .status
+        .set_description(Some(&gtk4::glib::markup_escape_text(description)));
     ui.shared.retry.set_visible(retry);
     ui.shared.content.set_visible_child_name("status");
 }
@@ -484,9 +486,7 @@ fn repaint_shared_crumb(ui: &Rc<Ui>, nav: &[(String, String)]) {
         nav.is_empty(),
     ));
     for (i, (_, name)) in nav.iter().enumerate() {
-        let sep = gtk4::Label::new(Some("›"));
-        sep.add_css_class("dim-label");
-        crumb.append(&sep);
+        crumb.append(&crumb_separator());
         crumb.append(&shared_crumb_node(ui, name, i + 1, i + 1 == nav.len()));
     }
 }
@@ -495,12 +495,7 @@ fn repaint_shared_crumb(ui: &Rc<Ui>, nav: &[(String, String)]) {
 /// that goes back up to `depth` folders below the top level.
 fn shared_crumb_node(ui: &Rc<Ui>, label: &str, depth: usize, current: bool) -> gtk4::Widget {
     if current {
-        let l = gtk4::Label::builder()
-            .label(label)
-            .ellipsize(gtk4::pango::EllipsizeMode::Start)
-            .build();
-        l.add_css_class("heading");
-        return l.upcast();
+        return crumb_current(label);
     }
     let button = gtk4::Button::builder().label(label).build();
     button.add_css_class("flat");
@@ -825,6 +820,7 @@ fn invitation_row(inv: &InvitationInfo) -> adw::ActionRow {
         .title(&item)
         // Translators: {email} is the address of the person who sent the invitation.
         .subtitle(gettext_f("From {email}", &[("email", &inv.inviter_email)]))
+        .use_markup(false)
         .build();
     row.add_prefix(&gtk4::Image::from_icon_name(if inv.is_dir {
         "folder-symbolic"
@@ -869,6 +865,7 @@ fn repaint_links(ui: &Rc<Ui>, bookmarks: &[BookmarkInfo]) {
         let row = adw::ActionRow::builder()
             .title(&title)
             .subtitle(&bm.url)
+            .use_markup(false)
             .subtitle_lines(1)
             .activatable(true)
             .tooltip_text(gettext("Open in browser"))

crates/pdfs-gui/src/app/pages/shared_by_me.rs

@@ -329,7 +329,9 @@ pub(crate) fn shared_by_me_status(
 ) {
     ui.shared_by_me.status.set_icon_name(Some(icon));
     ui.shared_by_me.status.set_title(title);
-    ui.shared_by_me.status.set_description(Some(description));
+    ui.shared_by_me
+        .status
+        .set_description(Some(&gtk4::glib::markup_escape_text(description)));
     ui.shared_by_me.retry.set_visible(retry);
     ui.shared_by_me.content.set_visible_child_name("status");
     ui.shared_by_me.subtitle.set_subtitle("");
@@ -565,6 +567,7 @@ pub(crate) fn prompt_stop_sharing(ui: &Rc<Ui>, entries: &[DirEntry]) {
     let uids: Vec<String> = entries.iter().map(|e| e.uid.clone()).collect();
     dialog.connect_response(Some("stop"), move |_, _| {
         let done = done.clone();
+        let stopped = uids.clone();
         run_requests(
             &ui_c,
             uids.iter()
@@ -572,6 +575,7 @@ pub(crate) fn prompt_stop_sharing(ui: &Rc<Ui>, entries: &[DirEntry]) {
                 .collect(),
             gettext_noop("Couldn't stop sharing"),
             move |ui| {
+                forget_shared_by_me(ui, &stopped);
                 reload_listing(ui);
                 toast(ui, &done);
             },
@@ -580,6 +584,18 @@ pub(crate) fn prompt_stop_sharing(ui: &Rc<Ui>, entries: &[DirEntry]) {
     dialog.present(ui_window(ui).as_ref());
 }
 
+/// Take items whose sharing just stopped off the page now, rather than when
+/// the reload that confirms it comes back: that reload asks after every share
+/// in turn and takes a while with many of them.
+fn forget_shared_by_me(ui: &Rc<Ui>, uids: &[String]) {
+    let items = {
+        let mut items = ui.shared_by_me.items.borrow_mut();
+        items.retain(|item| !uids.contains(&item.uid));
+        items.clone()
+    };
+    repaint_shared_by_me(ui, &items);
+}
+
 /// Open a shared item: a folder in My Files, a file the way My Files would.
 fn open_shared_by_me(ui: &Rc<Ui>, entry: &DirEntry) {
     if entry.is_dir {
@@ -608,6 +624,7 @@ pub(crate) fn shared_item_as_entry(item: &SharedItem) -> DirEntry {
         size: 0,
         modified: item.modified,
         pinned: false,
+        pinned_by_folder: false,
         cached: false,
         uid: item.uid.clone(),
         path: item.path.clone(),

crates/pdfs-gui/src/app/pages/status.rs

@@ -52,6 +52,9 @@ pub(crate) struct StatusState {
     pub(crate) online_map_row: adw::SwitchRow,
     /// "Show tray icon" toggle. Guarded by [`Self::settings_suppress`].
     pub(crate) tray_row: adw::SwitchRow,
+    /// "Check for updates" toggle, not shown where a package manager brings
+    /// updates. Guarded by [`Self::settings_suppress`].
+    pub(crate) update_row: adw::SwitchRow,
     /// Language picker: "System Default", then [`i18n::LANGUAGES`]. Guarded by
     /// [`Self::settings_suppress`].
     pub(crate) language_row: adw::ComboRow,
@@ -164,6 +167,7 @@ pub(crate) struct MainWidgets {
     pub(crate) theme_row: adw::SwitchRow,
     pub(crate) online_map_row: adw::SwitchRow,
     pub(crate) tray_row: adw::SwitchRow,
+    pub(crate) update_row: adw::SwitchRow,
     pub(crate) language_row: adw::ComboRow,
 }
 
@@ -250,6 +254,17 @@ pub(crate) fn build_main_page() -> MainWidgets {
     let language_row = build_language_row();
     appearance_group.add(&language_row);
 
+    let updates_group = adw::PreferencesGroup::builder()
+        .title(gettext("Updates"))
+        .build();
+    let update_row = adw::SwitchRow::builder()
+        .title(gettext("Check for updates"))
+        .subtitle(gettext(
+            "Ask GitHub once a day whether a new version is out. GitHub learns your IP address and which version you use.",
+        ))
+        .build();
+    updates_group.add(&update_row);
+
     let general = adw::PreferencesPage::builder()
         .title(gettext("General"))
         .icon_name("preferences-system-symbolic")
@@ -258,6 +273,10 @@ pub(crate) fn build_main_page() -> MainWidgets {
     general.add(&location_group);
     general.add(&network_group);
     general.add(&appearance_group);
+    // A package manager brings new versions, so there is nothing to tell.
+    if !updates_managed_here() {
+        general.add(&updates_group);
+    }
 
     // ---- Preferences: Storage
     let storage_group = adw::PreferencesGroup::builder()
@@ -381,23 +400,34 @@ pub(crate) fn build_main_page() -> MainWidgets {
         .hexpand(true)
         .ellipsize(gtk4::pango::EllipsizeMode::Middle)
         .build();
+    // The app's one menu, on the account row the way Proton's own apps keep it:
+    // app-wide entries first, the account's last. The whole row opens it, and
+    // F10 too, as the primary menu.
+    let app_section = gio::Menu::new();
+    app_section.append(Some(&gettext("Preferences")), Some("win.preferences"));
+    app_section.append(Some(&gettext("Keyboard Shortcuts")), Some("win.shortcuts"));
+    app_section.append(
+        Some(&gettext("About Proton Drive for Linux")),
+        Some("win.about"),
+    );
+    let account_section = gio::Menu::new();
+    account_section.append(Some(&gettext("Sign Out…")), Some("win.sign-out"));
     let account_menu = gio::Menu::new();
-    account_menu.append(Some(&gettext("Preferences")), Some("win.preferences"));
-    let sign_out = gio::Menu::new();
-    sign_out.append(Some(&gettext("Sign Out…")), Some("win.sign-out"));
-    account_menu.append_section(None, &sign_out);
-    let account_button = gtk4::MenuButton::builder()
-        .icon_name("view-more-symbolic")
-        .tooltip_text(gettext("Account"))
+    account_menu.append_section(None, &app_section);
+    account_menu.append_section(None, &account_section);
+    let row = gtk4::Box::new(gtk4::Orientation::Horizontal, 10);
+    row.append(&avatar);
+    row.append(&account_name);
+    row.append(&gtk4::Image::from_icon_name("view-more-symbolic"));
+    let account = gtk4::MenuButton::builder()
+        .child(&row)
+        .tooltip_text(gettext("Main menu"))
         .menu_model(&account_menu)
-        .valign(gtk4::Align::Center)
+        .direction(gtk4::ArrowType::Up)
+        .primary(true)
         .build();
-    account_button.add_css_class("flat");
-    let account = gtk4::Box::new(gtk4::Orientation::Horizontal, 10);
+    account.add_css_class("flat");
     account.add_css_class("sidebar-account");
-    account.append(&avatar);
-    account.append(&account_name);
-    account.append(&account_button);
 
     let footer = gtk4::Box::new(gtk4::Orientation::Vertical, 10);
     footer.add_css_class("sidebar-footer");
@@ -431,6 +461,7 @@ pub(crate) fn build_main_page() -> MainWidgets {
         theme_row,
         online_map_row,
         tray_row,
+        update_row,
         language_row,
     }
 }
@@ -530,6 +561,7 @@ pub(crate) fn wire_settings(
         .set_active(config.proton_theme.unwrap_or(false));
     ui.status.online_map_row.set_active(config.online_map);
     ui.status.tray_row.set_active(!config.tray_hidden);
+    ui.status.update_row.set_active(config.update_check);
     ui.status
         .language_row
         .set_selected(language_index(config.language.as_deref()));
@@ -679,6 +711,26 @@ pub(crate) fn wire_settings(
         }
     });
 
+    // Update check: saved, and the first check runs right away if one is due.
+    let ui_update = ui.clone();
+    ui.status.update_row.connect_active_notify(move |row| {
+        if ui_update.status.settings_suppress.get() {
+            return;
+        }
+        let mut config = ui_update.dirs.load_config();
+        config.update_check = row.is_active();
+        if let Err(e) = ui_update.dirs.save_config(&config) {
+            toast_error(
+                &ui_update,
+                &gettext("Couldn't save the update setting"),
+                &e.to_string(),
+            );
+            return;
+        }
+        show_latest(&ui_update);
+        start_update_checks(&ui_update);
+    });
+
     // Tray icon: the tray reads the same flag at start, so hiding it here also
     // keeps the login autostart from bringing it back.
     let ui_tray = ui.clone();
@@ -754,7 +806,8 @@ pub(crate) fn settings_request(ui: &Rc<Ui>, req: Request, done: String, failed:
 }
 
 /// Prompt for a new mountpoint folder, persist it to config, and offer to restart
-/// the mount service so the daemon picks it up.
+/// the mount service so the daemon picks it up. A folder with files in it is
+/// refused: the mount would hide them (B277).
 pub(crate) fn prompt_mountpoint(ui: &Rc<Ui>) {
     let win = ui_window(ui);
     let dialog = gtk4::FileDialog::builder()
@@ -764,46 +817,89 @@ pub(crate) fn prompt_mountpoint(ui: &Rc<Ui>) {
     dialog.select_folder(win.as_ref(), gio::Cancellable::NONE, move |res| {
         let Ok(folder) = res else { return };
         let Some(path) = folder.path() else { return };
-        let path_str = path.display().to_string();
-
-        // Persist the choice to config so the next mount uses it.
-        let mut config = ui.dirs.load_config();
-        config.mountpoint = Some(path_str.clone());
-        if let Err(e) = ui.dirs.save_config(&config) {
-            toast_error(&ui, &gettext("Couldn't save the folder"), &e.to_string());
+        // The folder My files is mounted at lists Drive's files, not its own,
+        // so picking it again is not checked.
+        if path == ui.dirs.resolved_mountpoint(&ui.dirs.load_config()) {
+            use_mountpoint(&ui, &path);
             return;
         }
-        ui.status.mountpoint_row.set_subtitle(&path_str);
-        // The Locations page shows the same path as a row title. Any other page
-        // reads it again on the next visit.
-        if ui.stack.visible_child_name().as_deref() == Some("locations") {
-            load_locations(&ui);
-        }
-
-        // The daemon only reads the mountpoint at mount time, so offer a restart.
-        let confirm = adw::AlertDialog::builder()
-            .heading(gettext("Restart Proton Drive?"))
-            // Translators: {path} is the folder the drive is mounted at.
-            .body(gettext_f(
-                "My files now appears in “{path}” after Proton Drive restarts.",
-                &[("path", &path_str)],
-            ))
-            .build();
-        confirm.add_response("later", &gettext("Later"));
-        confirm.add_response("restart", &gettext("Restart Now"));
-        confirm.set_response_appearance("restart", adw::ResponseAppearance::Suggested);
-        confirm.set_default_response(Some("restart"));
-        confirm.set_close_response("later");
-        let ui_restart = ui.clone();
-        confirm.connect_response(None, move |_, resp| {
-            if resp == "restart" {
-                restart_service_then(&ui_restart, |_| {});
+        let ui = ui.clone();
+        glib::spawn_future_local(async move {
+            let checked = path.clone();
+            let found = gio::spawn_blocking(move || pdfs_core::mountpoint::not_empty(&checked))
+                .await
+                .unwrap_or_else(|_| Err(std::io::Error::other("the check did not finish")));
+            match found {
+                Ok(None) => use_mountpoint(&ui, &path),
+                Ok(Some(found)) => refuse_mountpoint(&ui, &found),
+                Err(e) => toast_error(&ui, &gettext("Couldn't read the folder"), &e.to_string()),
             }
         });
-        confirm.present(ui_window(&ui).as_ref());
     });
 }
 
+/// Explain why the folder `found` cannot hold My files.
+fn refuse_mountpoint(ui: &Rc<Ui>, found: &pdfs_core::mountpoint::NotEmpty) {
+    let path = found.path.display().to_string();
+    let dialog = adw::AlertDialog::builder()
+        .heading(gettext("Choose an Empty Folder"))
+        // Translators: {path} is the folder the user picked; {n} is how many
+        // files and folders are already in it.
+        .body(ngettext_f(
+            "“{path}” already has {n} item in it. My files would hide it while Proton Drive runs, and it would not be uploaded.",
+            "“{path}” already has {n} items in it. My files would hide them while Proton Drive runs, and they would not be uploaded.",
+            found.count as u64,
+            &[("path", &path)],
+        ))
+        .build();
+    dialog.add_response("close", &gettext("Close"));
+    dialog.set_default_response(Some("close"));
+    dialog.set_close_response("close");
+    dialog.present(ui_window(ui).as_ref());
+}
+
+/// Make `path` the folder My files is mounted at, and offer the restart that
+/// moves it there.
+fn use_mountpoint(ui: &Rc<Ui>, path: &std::path::Path) {
+    let path_str = path.display().to_string();
+
+    // Persist the choice to config so the next mount uses it.
+    let mut config = ui.dirs.load_config();
+    config.mountpoint = Some(path_str.clone());
+    if let Err(e) = ui.dirs.save_config(&config) {
+        toast_error(ui, &gettext("Couldn't save the folder"), &e.to_string());
+        return;
+    }
+    ui.status.mountpoint_row.set_subtitle(&path_str);
+    // The Locations page shows the same path as a row title. Any other page
+    // reads it again on the next visit.
+    if ui.stack.visible_child_name().as_deref() == Some("locations") {
+        load_locations(ui);
+    }
+
+    // The daemon only reads the mountpoint at mount time, so offer a restart.
+    let confirm = adw::AlertDialog::builder()
+        .heading(gettext("Restart Proton Drive?"))
+        // Translators: {path} is the folder the drive is mounted at.
+        .body(gettext_f(
+            "My files now appears in “{path}” after Proton Drive restarts.",
+            &[("path", &path_str)],
+        ))
+        .build();
+    confirm.add_response("later", &gettext("Later"));
+    confirm.add_response("restart", &gettext("Restart Now"));
+    confirm.set_response_appearance("restart", adw::ResponseAppearance::Suggested);
+    confirm.set_default_response(Some("restart"));
+    confirm.set_close_response("later");
+    let ui_restart = ui.clone();
+    confirm.connect_response(None, move |_, resp| {
+        if resp == "restart" {
+            restart_service_then(&ui_restart, |_| {});
+        }
+    });
+    confirm.present(ui_window(ui).as_ref());
+}
+
 /// Connect the Files/Photos "Retry" buttons (shown by [`browser_unreachable`] /
 /// [`gallery_unreachable`] when the mount is down): restart the systemd unit and
 /// reload the page.
@@ -825,6 +921,13 @@ pub(crate) fn wire_retry(ui: &Rc<Ui>) {
         .connect_clicked(move |_| restart_service_then(&ui_trash, load_trash));
 }
 
+/// Show the sign-in page while a session is still stored, because Proton has
+/// refused it. The sidebar stays, so the user can go back to cached files; a
+/// login moves on to the files as from any sign-in ([`refresh`]).
+pub(crate) fn show_login(ui: &Rc<Ui>) {
+    ui.stack.set_visible_child_name("login");
+}
+
 /// Repaint the window from the cached login identity, then ask the daemon for
 /// its status and transfers. Runs at startup, after a login and after a service
 /// restart; the daemon's event feed keeps both current in between. The identity
@@ -842,7 +945,7 @@ pub(crate) fn refresh(ui: &Rc<Ui>) {
                 if ui.stack.visible_child_name().as_deref() == Some("login") {
                     ui.stack.set_visible_child_name("browser");
                 }
-                ui.nav.set_collapsed(false);
+                ui.nav.set_collapsed(ui.narrow.get());
                 if ui.status.account_name.label() != s.username {
                     ui.status.account_name.set_label(&s.username);
                     ui.status.account_name.set_tooltip_text(Some(&s.username));
@@ -860,6 +963,7 @@ pub(crate) fn refresh(ui: &Rc<Ui>) {
         }
     }
 
+    offer_unlock(ui);
     refresh_status(ui);
     refresh_transfers(ui);
 }
@@ -939,7 +1043,9 @@ fn quota_display(max_space: i64, used_space: i64) -> (f64, String) {
 pub(crate) fn set_mounted(ui: &Rc<Ui>, mounted: bool) {
     *ui.mounted.borrow_mut() = mounted;
     sync_mounted_actions(ui, mounted);
-    ui.gallery.upload.set_sensitive(mounted);
+    ui.gallery
+        .upload
+        .set_sensitive(mounted && ui.gallery.library.get());
     ui.details.details.pin_row.set_sensitive(mounted);
     ui.details.details.rename_button.set_sensitive(mounted);
     ui.details.details.trash_button.set_sensitive(mounted);
@@ -1209,6 +1315,9 @@ pub(crate) fn paint_status(ui: &Rc<Ui>, status: Response) {
         failing_error,
         paused,
         paused_until,
+        session_expired,
+        tokens_unsaved,
+        version,
         ..
     } = status
     else {
@@ -1219,7 +1328,13 @@ pub(crate) fn paint_status(ui: &Rc<Ui>, status: Response) {
     // in it: it is why a file that looks saved is not on the remote
     // yet, and offline is usually the reason it is still queued.
     let queued = i18n::pending_summary(pending_uploads, pending_changes);
-    let state = if paused {
+    let state = if session_expired {
+        SyncState::SessionExpired { queued }
+    } else if tokens_unsaved {
+        SyncState::TokensUnsaved
+    } else if pdfs_core::control::daemon_outdated(&version) {
+        SyncState::Outdated { running: version }
+    } else if paused {
         SyncState::Paused {
             until: paused_until,
             queued,
@@ -1272,16 +1387,57 @@ pub(crate) fn paint_status(ui: &Rc<Ui>, status: Response) {
 /// read-out so the page doesn't flicker on a blip.
 pub(crate) fn paint_disconnected(ui: &Rc<Ui>) {
     set_mounted(ui, false);
-    paint_sync_status(ui, SyncState::Disconnected);
     for r in ui.status.pin_rows.borrow().iter() {
         if let Some(b) = &r.unpin {
             b.set_sensitive(false);
         }
     }
+    // A running daemon whose mount fails on every try never answers either,
+    // and "isn't running" would be wrong for it (B263, B277). The pages read
+    // the same failure record.
+    let ui = ui.clone();
+    glib::spawn_future_local(async move {
+        let failure = if service_down().await {
+            None
+        } else {
+            let state_dir = ui.dirs.state_dir();
+            gio::spawn_blocking(move || pdfs_core::mountfail::read(&state_dir))
+                .await
+                .ok()
+                .flatten()
+        };
+        // The daemon may have answered while this looked.
+        if *ui.mounted.borrow() {
+            return;
+        }
+        paint_sync_status(
+            &ui,
+            match failure {
+                Some(failure) => SyncState::CannotOpen {
+                    not_empty: failure.not_empty.is_some(),
+                },
+                None => SyncState::Disconnected,
+            },
+        );
+    });
 }
 
 /// What the sidebar's status strip reports, most urgent first.
 pub(crate) enum SyncState {
+    /// Proton refused the session: nothing reaches it until the user signs in
+    /// again. Outranks a pause, which it makes moot.
+    SessionExpired {
+        queued: Option<String>,
+    },
+    /// The keyring refuses the session's refreshed tokens. Sync goes on, but
+    /// a reboot before the keyring takes them signs the user out.
+    TokensUnsaved,
+    /// The daemon is an older release than this window: an upgrade replaced
+    /// the files but left the service running, with the old release's bugs,
+    /// until it restarts (#33). `running` is empty when it is too old to say.
+    Outdated {
+        running: String,
+    },
     /// The user paused syncing; nothing goes up until it resumes. Outranks
     /// everything else, because it is the reason for everything else.
     Paused {
@@ -1307,6 +1463,11 @@ pub(crate) enum SyncState {
     },
     /// No mount daemon answered: still starting, or the service is down.
     Disconnected,
+    /// The service runs, but its mount fails on every try. `not_empty` when
+    /// it refuses a folder that already has files in it.
+    CannotOpen {
+        not_empty: bool,
+    },
     /// The daemon is running but didn't answer in time.
     NotResponding,
 }
@@ -1315,8 +1476,48 @@ pub(crate) enum SyncState {
 /// one-line state, and a detail line.
 fn paint_sync_status(ui: &Rc<Ui>, state: SyncState) {
     let paused = matches!(state, SyncState::Paused { .. });
-    let connected = !matches!(state, SyncState::Disconnected | SyncState::NotResponding);
+    let connected = !matches!(
+        state,
+        SyncState::Disconnected | SyncState::CannotOpen { .. } | SyncState::NotResponding
+    );
+    let expired = matches!(state, SyncState::SessionExpired { .. });
+    let outdated = matches!(state, SyncState::Outdated { .. });
     let (icon, class, title, detail) = match state {
+        SyncState::SessionExpired { queued } => (
+            "dialog-password-symbolic",
+            Some("error"),
+            gettext("Session expired"),
+            Some(match queued {
+                // Translators: {queued} says what is waiting, such as "3 uploads
+                // queued".
+                Some(queued) => {
+                    gettext_f("{queued} · sign in again to sync", &[("queued", &queued)])
+                }
+                None => gettext("Sign in again to sync"),
+            }),
+        ),
+        SyncState::TokensUnsaved => (
+            "dialog-warning-symbolic",
+            Some("warning"),
+            gettext("Sign-in not saved"),
+            Some(gettext(
+                "Unlock your keyring, or the next reboot signs you out",
+            )),
+        ),
+        SyncState::Outdated { running } => (
+            "dialog-warning-symbolic",
+            Some("warning"),
+            gettext("Restart to finish updating"),
+            Some(if running.is_empty() {
+                gettext("An older version of Proton Drive is still running")
+            } else {
+                // Translators: {version} is a release number such as "3.2.0".
+                gettext_f(
+                    "Proton Drive {version} is still running",
+                    &[("version", &running)],
+                )
+            }),
+        ),
         SyncState::Paused { until, queued } => (
             "media-playback-pause-symbolic",
             Some("warning"),
@@ -1370,6 +1571,16 @@ fn paint_sync_status(ui: &Rc<Ui>, state: SyncState) {
             gettext("Not connected"),
             Some(gettext("Proton Drive isn't running")),
         ),
+        SyncState::CannotOpen { not_empty } => (
+            "dialog-warning-symbolic",
+            Some("warning"),
+            gettext("Can't open your Drive"),
+            Some(if not_empty {
+                gettext("Your Proton Drive folder isn't empty")
+            } else {
+                gettext("Proton Drive keeps trying to start")
+            }),
+        ),
         SyncState::NotResponding => (
             "dialog-warning-symbolic",
             Some("warning"),
@@ -1387,6 +1598,8 @@ fn paint_sync_status(ui: &Rc<Ui>, state: SyncState) {
     if let Some(class) = class {
         image.add_css_class(class);
     }
+    ui.locations.card.sign_in.set_visible(expired);
+    ui.locations.card.restart.set_visible(outdated);
     ui.status.status_title.set_label(&title);
     ui.status.status_detail.set_visible(detail.is_some());
     ui.status
@@ -1455,7 +1668,7 @@ pub(crate) fn repaint_pins(ui: &Rc<Ui>, pins: &[pdfs_core::cache::Pin], mounted:
         let row = adw::ActionRow::builder()
             .title(gettext("No files kept offline"))
             .subtitle(gettext(
-                "Right-click a file and choose “Make available offline”.",
+                "Right-click a file or folder and choose “Available offline”.",
             ))
             .build();
         ui.status.pins_group.add(&row);
@@ -1483,6 +1696,7 @@ pub(crate) fn repaint_pins(ui: &Rc<Ui>, pins: &[pdfs_core::cache::Pin], mounted:
         let row = adw::ActionRow::builder()
             .title(&name)
             .subtitle(&pin.path)
+            .use_markup(false)
             .build();
         let icon = gtk4::Image::from_icon_name("pdfs-offline-symbolic");
         row.add_prefix(&icon);

crates/pdfs-gui/src/app/pages/takeout.rs

@@ -510,6 +510,7 @@ pub(crate) fn repaint_archives(ui: &Rc<Ui>) {
                         .unwrap_or_else(|| path.display().to_string()),
                 )
                 .subtitle(human_bytes(size))
+                .use_markup(false)
                 .build();
             let remove = gtk4::Button::builder()
                 .icon_name("edit-delete-symbolic")
@@ -645,7 +646,12 @@ pub(crate) fn refresh_takeout(ui: &Rc<Ui>) {
             // An import runs for hours, so its ending is announced rather than
             // left to be discovered: a toast for whoever is looking at the
             // window, and a desktop notification for whoever is not.
-            if was_running {
+            let failed = summary.as_ref().and_then(|s| s.error.clone());
+            if was_running && let Some(error) = &failed {
+                let headline = gettext("Couldn't import from Google Photos");
+                toast_error(&ui, &headline, error);
+                notify("takeout-import", &headline, error);
+            } else if was_running {
                 let dry = ui.takeout.dry_run.get();
                 let headline = if dry {
                     gettext("Scan finished")
@@ -701,7 +707,18 @@ fn repaint_summary(ui: &Rc<Ui>, summary: &ImportSummary) {
     } else {
         gettext("Last import")
     });
-    ui.takeout.summary_group.set_description(Some(&if dry {
+    ui.takeout.summary_group.set_description(Some(&if let Some(error) = &summary.error {
+        // The reason is the service's own text, which is not translated. A
+        // group's description is markup, and the reason may name a path.
+        glib::markup_escape_text(&gettext_f(
+            "{what}: {detail}",
+            &[
+                ("what", &gettext("Couldn't import from Google Photos")),
+                ("detail", error),
+            ],
+        ))
+        .to_string()
+    } else if dry {
         gettext("Nothing was uploaded — this is what an import would do.")
     } else if summary.cancelled {
         gettext("Stopped early. Everything uploaded so far is in your timeline; run it again to continue where it left off.")

crates/pdfs-gui/src/app/pages/trash.rs

@@ -330,7 +330,9 @@ pub(crate) fn trash_unreachable(ui: &Rc<Ui>) {
 pub(crate) fn trash_status(ui: &Rc<Ui>, icon: &str, title: &str, description: &str, retry: bool) {
     ui.trash.status.set_icon_name(Some(icon));
     ui.trash.status.set_title(title);
-    ui.trash.status.set_description(Some(description));
+    ui.trash
+        .status
+        .set_description(Some(&gtk4::glib::markup_escape_text(description)));
     ui.trash.retry.set_visible(retry);
     ui.trash.content.set_visible_child_name("status");
     ui.trash.subtitle.set_subtitle("");
@@ -524,6 +526,7 @@ mod tests {
             size: 0,
             modified,
             pinned: false,
+            pinned_by_folder: false,
             cached: false,
             uid: name.into(),
             path: String::new(),

crates/pdfs-gui/src/app/pages/verify.rs

@@ -1,4 +1,4 @@
-//! The human-verification (CAPTCHA) dialog.
+//! The human-verification (CAPTCHA) window.
 //!
 //! Proton gates logins it does not recognise — a new IP, a VPN exit — behind a
 //! CAPTCHA. The API answers the login with a challenge instead of a session, and
@@ -8,10 +8,26 @@
 //! The page is hosted in a `WebKitWebView` rather than handed to the system
 //! browser because it reports completion by posting a message to its host, not
 //! by redirecting: a browser has nowhere to post it back to.
+//!
+//! The webview runs in a child `pdfs-app` started with [`VERIFY_ARG`], not in the
+//! app itself. WebKit aborts its whole process when its sandbox cannot start, as
+//! on hardened systems that keep bubblewrap from the journal socket
+//! (`docs/BUGS.md` B195); in a child that costs the verification, not the app.
+//! The URL goes to the child on stdin, so it never shows in a process list, and
+//! the token comes back on stdout.
 
 use crate::*;
+use std::io::{BufRead, BufReader, Write as _};
+use std::process::{ExitStatus, Stdio};
 use webkit6::prelude::*;
 
+/// The argument that makes `pdfs-app` the verification window instead of the app.
+pub(crate) const VERIFY_ARG: &str = "--human-verification";
+
+/// Marks the token among whatever else lands on the child's stdout: GLib and
+/// WebKit write debug output there.
+const TOKEN_PREFIX: &str = "hv-token ";
+
 /// Bridge the verification page's `postMessage` to a handler this side can read.
 ///
 /// The page targets its embedding host (`window.parent`), which in a webview is
@@ -26,15 +42,100 @@ window.addEventListener('message', function (event) {
 });
 "#;
 
-/// Present the challenge and hand the solved token back through `token_tx`.
-///
-/// Closing the dialog without solving drops the sender, which the waiting login
-/// worker reads as a cancelled sign-in — the same contract as the 2FA prompt.
-pub(crate) fn prompt_human_verification(
-    ui: &Rc<Ui>,
-    url: &str,
-    token_tx: std::sync::mpsc::Sender<String>,
-) {
+/// How the verification window ended.
+#[derive(Debug, PartialEq, Eq)]
+pub(crate) enum Verification {
+    Solved(String),
+    /// Closed without solving.
+    Cancelled,
+    /// Never came up, or died: most likely WebKit could not start its sandbox.
+    Failed,
+}
+
+/// Show the challenge in the verification window and wait until it closes.
+pub(crate) async fn verify_human(url: String) -> Verification {
+    match gio::spawn_blocking(move || run_verification_child(&url)).await {
+        Ok(Ok(verification)) => verification,
+        Ok(Err(e)) => {
+            tracing::error!("cannot run the verification window: {e}");
+            Verification::Failed
+        }
+        Err(_) => Verification::Failed,
+    }
+}
+
+fn run_verification_child(url: &str) -> std::io::Result<Verification> {
+    let mut child = Command::new(own_exe())
+        .arg(VERIFY_ARG)
+        .stdin(Stdio::piped())
+        .stdout(Stdio::piped())
+        .spawn()?;
+    if let Some(mut stdin) = child.stdin.take() {
+        // A failed write means the child is already gone; its exit status says
+        // how. Dropping `stdin` closes it.
+        let _ = writeln!(stdin, "{url}");
+    }
+    // Stops reading at the token rather than at EOF: WebKit's helper processes
+    // inherit the pipe and may hold it open a moment after the child quits.
+    let token = child
+        .stdout
+        .take()
+        .and_then(|out| find_token(BufReader::new(out)));
+    let status = child.wait()?;
+    Ok(outcome(token, status))
+}
+
+/// This very binary, so a development build opens its own window. After an
+/// upgrade replaced the file, `current_exe` names a deleted path, and the
+/// installed `pdfs-app` is the next best.
+fn own_exe() -> PathBuf {
+    std::env::current_exe()
+        .ok()
+        .filter(|path| path.is_file())
+        .unwrap_or_else(|| PathBuf::from("pdfs-app"))
+}
+
+fn find_token(out: impl BufRead) -> Option<String> {
+    out.lines()
+        .map_while(Result::ok)
+        .find_map(|line| line.strip_prefix(TOKEN_PREFIX).map(str::to_owned))
+}
+
+/// A token wins over the exit status: the user solved the page, even if
+/// WebKit's teardown crashed after it.
+fn outcome(token: Option<String>, status: ExitStatus) -> Verification {
+    match token {
+        Some(token) => Verification::Solved(token),
+        None if status.success() => Verification::Cancelled,
+        None => {
+            tracing::error!(%status, "the verification window failed");
+            Verification::Failed
+        }
+    }
+}
+
+/// Run as the verification window: read the page's URL from stdin, show it, and
+/// print the token once the user has solved it. Closing the window exits
+/// without a token, which the app reads as a cancelled sign-in.
+pub(crate) fn run_verification_window() -> glib::ExitCode {
+    let mut url = String::new();
+    if std::io::stdin().lock().read_line(&mut url).is_err() || url.trim().is_empty() {
+        tracing::error!("{VERIFY_ARG} expects the verification URL on stdin");
+        return glib::ExitCode::FAILURE;
+    }
+    let url = url.trim().to_owned();
+
+    // Not unique: the app that started it already holds APP_ID.
+    let app = adw::Application::builder()
+        .flags(gio::ApplicationFlags::NON_UNIQUE)
+        .build();
+    app.connect_activate(move |app| build_verification_window(app, &url));
+    // GApplication would refuse VERIFY_ARG as an unknown option.
+    let argv0 = std::env::args().next().unwrap_or_default();
+    app.run_with_args(&[argv0])
+}
+
+fn build_verification_window(app: &adw::Application, url: &str) {
     let content = webkit6::UserContentManager::new();
     content.add_script(&webkit6::UserScript::new(
         BRIDGE,
@@ -53,24 +154,19 @@ pub(crate) fn prompt_human_verification(
         .hexpand(true)
         .build();
 
-    let dialog = adw::Dialog::builder()
+    let body = gtk4::Box::new(gtk4::Orientation::Vertical, 0);
+    body.append(&adw::HeaderBar::new());
+    body.append(&webview);
+    let window = adw::ApplicationWindow::builder()
+        .application(app)
         .title(gettext("Verification"))
-        .content_width(420)
-        .content_height(560)
+        .icon_name(APP_ID)
+        .default_width(420)
+        .default_height(560)
+        .content(&body)
         .build();
 
-    let header = adw::HeaderBar::new();
-    let body = gtk4::Box::new(gtk4::Orientation::Vertical, 0);
-    body.append(&header);
-    body.append(&webview);
-    dialog.set_child(Some(&body));
-
-    // Taken on the first success *or* on close, so the token is sent at most
-    // once and a cancelled dialog always drops the sender.
-    let token_tx = Rc::new(RefCell::new(Some(token_tx)));
-
-    let tx = token_tx.clone();
-    let dlg_weak = dialog.downgrade();
+    let app = app.downgrade();
     content.connect_script_message_received(Some("hv"), move |_, value| {
         let Some(token) = extract_token(&value.to_str()) else {
             // Every `postMessage` on the page reaches here, most of them the
@@ -78,25 +174,17 @@ pub(crate) fn prompt_human_verification(
             // is simply not ours.
             return;
         };
-        if let Some(tx) = tx.borrow_mut().take() {
-            let _ = tx.send(token);
+        let mut stdout = std::io::stdout().lock();
+        if let Err(e) = writeln!(stdout, "{TOKEN_PREFIX}{token}").and_then(|()| stdout.flush()) {
+            tracing::error!("cannot hand the verification token back: {e}");
         }
-        if let Some(dlg) = dlg_weak.upgrade() {
-            dlg.close();
+        if let Some(app) = app.upgrade() {
+            app.quit();
         }
     });
 
-    // Covers the close button, Escape, and the user giving up.
-    dialog.connect_closed(move |_| {
-        token_tx.borrow_mut().take();
-    });
-
     webview.load_uri(url);
-
-    let parent = ui.login.login_button.root().and_downcast::<gtk4::Window>();
-    // Returns immediately; the login worker stays blocked on the channel until
-    // the handler above sends, or the dialog closes and drops the sender.
-    dialog.present(parent.as_ref());
+    window.present();
 }
 
 /// Pull the verification token out of a message posted by the verification page.
@@ -133,7 +221,12 @@ fn extract_token(raw: &str) -> Option<String> {
 
 #[cfg(test)]
 mod tests {
-    use super::extract_token;
+    use super::{Verification, extract_token, find_token, outcome};
+    use std::os::unix::process::ExitStatusExt as _;
+    use std::process::ExitStatus;
+
+    /// The wait status of a process killed by SIGABRT.
+    const ABORTED: i32 = 6;
 
     #[test]
     fn a_completion_message_yields_its_token() {
@@ -163,4 +256,39 @@ mod tests {
             assert!(extract_token(raw).is_none(), "accepted: {raw}");
         }
     }
+
+    #[test]
+    fn the_token_is_found_among_other_output() {
+        let out = "Gtk-Message: something\nhv-token tok-1\nmore\n";
+        assert_eq!(find_token(out.as_bytes()).as_deref(), Some("tok-1"));
+        assert_eq!(find_token("only chatter\n".as_bytes()), None);
+    }
+
+    #[test]
+    fn a_window_closed_without_a_token_cancels() {
+        assert_eq!(
+            outcome(None, ExitStatus::from_raw(0)),
+            Verification::Cancelled
+        );
+    }
+
+    /// WebKit aborts when its sandbox cannot start (B195). That must read as a
+    /// failure the app explains, not as the user giving up.
+    #[test]
+    fn a_window_that_died_fails() {
+        assert_eq!(
+            outcome(None, ExitStatus::from_raw(ABORTED)),
+            Verification::Failed
+        );
+        let exited_1 = ExitStatus::from_raw(1 << 8);
+        assert_eq!(outcome(None, exited_1), Verification::Failed);
+    }
+
+    #[test]
+    fn a_token_counts_even_if_the_window_died_after_it() {
+        assert_eq!(
+            outcome(Some("tok-1".into()), ExitStatus::from_raw(ABORTED)),
+            Verification::Solved("tok-1".into())
+        );
+    }
 }

crates/pdfs-gui/src/app/update.rs

@@ -0,0 +1,168 @@
+//! Tells the user when a newer release is out, if they turned on Preferences →
+//! Updates. The decisions are [`pdfs_core::update`]'s; this asks GitHub and
+//! shows the banner.
+
+use crate::*;
+
+use std::time::{SystemTime, UNIX_EPOCH};
+
+use pdfs_core::update::{
+    RELEASES_LATEST_API, is_newer, latest_version, next_check_in, release_url, updates_managed,
+};
+
+/// How long one request to GitHub may take.
+const FETCH_TIMEOUT: Duration = Duration::from_secs(10);
+
+/// How long to wait after a failed check, such as one made offline, before
+/// trying again. Not saved, so a restart tries again straight away.
+const RETRY_AFTER: Duration = Duration::from_secs(60 * 60);
+
+pub(crate) struct UpdateState {
+    /// Over the sidebar, so it shows whichever page is open.
+    pub(crate) banner: adw::Banner,
+    /// The check loop is running. Turning the setting off and on again while it
+    /// sleeps must not start a second one.
+    running: Cell<bool>,
+    /// The release page the banner's button opens.
+    url: RefCell<String>,
+}
+
+impl UpdateState {
+    pub(crate) fn new() -> Self {
+        Self {
+            banner: adw::Banner::builder()
+                .button_label(gettext("Download"))
+                .build(),
+            running: Cell::new(false),
+            url: RefCell::new(String::new()),
+        }
+    }
+}
+
+/// Whether a package manager brings new releases to this install. The app then
+/// never asks, and Preferences does not offer to.
+pub(crate) fn updates_managed_here() -> bool {
+    std::env::current_exe().is_ok_and(|exe| updates_managed(&exe))
+}
+
+/// Wire the banner, show a release an earlier check found, and start checking
+/// if the user asked for it.
+pub(crate) fn wire_update(ui: &Rc<Ui>) {
+    let ui_open = ui.clone();
+    ui.update
+        .banner
+        .connect_button_clicked(move |_| open_uri(&ui_open.update.url.borrow()));
+    show_latest(ui);
+    start_update_checks(ui);
+}
+
+/// Start the daily check, unless it is off, managed elsewhere, or running.
+pub(crate) fn start_update_checks(ui: &Rc<Ui>) {
+    if updates_managed_here()
+        || !ui.dirs.load_config().update_check
+        || ui.update.running.replace(true)
+    {
+        return;
+    }
+    let ui = ui.clone();
+    glib::spawn_future_local(async move {
+        // Also kept here, so a config that cannot be saved does not make every
+        // pass ask GitHub again.
+        let mut checked = None;
+        loop {
+            let config = ui.dirs.load_config();
+            if !config.update_check {
+                break;
+            }
+            let wait = next_check_in(config.update_last_checked.max(checked), unix_now());
+            if !wait.is_zero() {
+                glib::timeout_future(wait).await;
+                continue;
+            }
+            match fetch_latest().await {
+                Ok(latest) => {
+                    checked = Some(unix_now());
+                    let mut config = ui.dirs.load_config();
+                    config.update_last_checked = checked;
+                    config.update_latest = latest;
+                    if let Err(e) = ui.dirs.save_config(&config) {
+                        tracing::warn!("update check: cannot save the result: {e}");
+                    }
+                    show_latest(&ui);
+                }
+                Err(e) => {
+                    tracing::warn!("update check: {e}");
+                    glib::timeout_future(RETRY_AFTER).await;
+                }
+            }
+        }
+        ui.update.running.set(false);
+    });
+}
+
+/// Reveal the banner if the last check found a release newer than this one,
+/// and hide it otherwise.
+pub(crate) fn show_latest(ui: &Ui) {
+    let config = ui.dirs.load_config();
+    let newer = config
+        .update_latest
+        .filter(|latest| config.update_check && is_newer(latest, env!("CARGO_PKG_VERSION")));
+    match newer {
+        Some(version) => {
+            ui.update.banner.set_title(&gettext_f(
+                "Proton Drive {version} is available",
+                &[("version", &version)],
+            ));
+            *ui.update.url.borrow_mut() = release_url(&version);
+            ui.update.banner.set_revealed(!updates_managed_here());
+        }
+        None => ui.update.banner.set_revealed(false),
+    }
+}
+
+fn unix_now() -> i64 {
+    SystemTime::now()
+        .duration_since(UNIX_EPOCH)
+        .map_or(0, |d| d.as_secs() as i64)
+}
+
+/// The latest release's version, asked on a worker thread so the window never
+/// waits on GitHub. `Ok(None)` when the answer names no `X.Y.Z` release.
+async fn fetch_latest() -> Result<Option<String>, String> {
+    let (tx, rx) = async_channel::bounded(1);
+    std::thread::spawn(move || {
+        let _ = tx.send_blocking(fetch_latest_blocking());
+    });
+    rx.recv().await.map_err(|e| e.to_string())?
+}
+
+fn fetch_latest_blocking() -> Result<Option<String>, String> {
+    let runtime = tokio::runtime::Builder::new_current_thread()
+        .enable_all()
+        .build()
+        .map_err(|e| format!("no runtime: {e}"))?;
+    let client = reqwest::Client::builder()
+        .user_agent(concat!(
+            "proton-drive-linux/",
+            env!("CARGO_PKG_VERSION"),
+            " (",
+            env!("CARGO_PKG_REPOSITORY"),
+            ")"
+        ))
+        .timeout(FETCH_TIMEOUT)
+        .build()
+        .map_err(|e| format!("no HTTP client: {e}"))?;
+    runtime.block_on(async {
+        let reply = client
+            .get(RELEASES_LATEST_API)
+            .header("Accept", "application/vnd.github+json")
+            .send()
+            .await
+            .map_err(|e| e.to_string())?;
+        if !reply.status().is_success() {
+            return Err(format!("GitHub answered {}", reply.status()));
+        }
+        let body = reply.bytes().await.map_err(|e| e.to_string())?;
+        Ok(latest_version(&body))
+    })
+}

crates/pdfs-gui/src/app/widgets/crumb.rs

@@ -0,0 +1,21 @@
+use crate::*;
+
+/// The "›" between two breadcrumb segments.
+pub(crate) fn crumb_separator() -> gtk4::Label {
+    let sep = gtk4::Label::new(Some("›"));
+    sep.add_css_class("dim-label");
+    sep
+}
+
+/// The last breadcrumb segment, the folder on screen: a heading rather than a
+/// button. It carries a flat button's side padding (`.crumb-current`), so the
+/// "›" before it sits as far from it as from the button before.
+pub(crate) fn crumb_current(label: &str) -> gtk4::Widget {
+    let l = gtk4::Label::builder()
+        .label(label)
+        .ellipsize(gtk4::pango::EllipsizeMode::Start)
+        .build();
+    l.add_css_class("heading");
+    l.add_css_class("crumb-current");
+    l.upcast()
+}

crates/pdfs-gui/src/app/widgets/details.rs

@@ -98,6 +98,8 @@ pub(crate) fn build_details_pane() -> (gtk4::Widget, DetailsWidgets) {
         .title(gettext("Location"))
         .subtitle("—")
         .subtitle_lines(3)
+        // A folder path, which may hold `&` or `<`.
+        .use_markup(false)
         .build();
     path_row.add_css_class("property");
     props.add(&size_row);
@@ -366,12 +368,19 @@ pub(crate) fn show_details(ui: &Rc<Ui>, entry: &DirEntry) {
     } else {
         gettext("File")
     });
-    d.size_row.set_subtitle(&if entry.is_dir {
-        "—".to_string()
+    // A folder's size is Proton Drive's count, which takes a request; it lands
+    // in `load_details_extras`.
+    if entry.is_dir {
+        d.size_row.set_title(&gettext("Size on Proton Drive"));
+        d.size_row.set_subtitle("—");
+        d.size_row.set_tooltip_text(Some(&gettext(
+            "Counted by Proton Drive, including items in the trash.",
+        )));
     } else {
-        human_bytes(entry.size)
-    });
-    d.size_row.set_visible(!entry.is_dir);
+        d.size_row.set_title(&pgettext("column", "Size"));
+        d.size_row.set_subtitle(&human_bytes(entry.size));
+        d.size_row.set_tooltip_text(None);
+    }
     d.modified_row
         .set_subtitle(&dates::short_date(entry.modified));
     let rel = entry_rel(ui, entry);
@@ -384,11 +393,20 @@ pub(crate) fn show_details(ui: &Rc<Ui>, entry: &DirEntry) {
     } else {
         parent.to_string()
     });
-    // Pinning is per file: the context menu and the selection bar offer it for
-    // files only, so the pane must not offer it for folders either.
+    // Kept through a pinned folder above it, the entry has no pin of its own
+    // to remove, so the switch shows that state without offering to change it.
     d.pin_row.set_active(entry.pinned);
-    d.pin_row.set_visible(!entry.is_dir);
-    d.pin_row.set_sensitive(*ui.mounted.borrow());
+    d.pin_row.set_subtitle(&if entry.pinned_by_folder {
+        gettext("Kept on this computer because a folder it is in is available offline.")
+    } else if entry.is_dir {
+        gettext(
+            "Keep a copy of everything in this folder on this computer, even without a connection.",
+        )
+    } else {
+        gettext("Keep a copy on this computer, even without a connection.")
+    });
+    d.pin_row
+        .set_sensitive(*ui.mounted.borrow() && !entry.pinned_by_folder);
     d.open_button.set_label(&if entry.is_dir {
         gettext("Open folder")
     } else {
@@ -415,8 +433,8 @@ pub(crate) fn show_details(ui: &Rc<Ui>, entry: &DirEntry) {
     d.pages.set_visible_child_name("details");
 }
 
-/// Fill the Sharing and Versions rows, which need the network. The answers
-/// land only if the pane still shows the same entry.
+/// Fill the Sharing and Versions rows, and a folder's size, which need the
+/// network. The answers land only if the pane still shows the same entry.
 fn load_details_extras(ui: &Rc<Ui>, entry: &DirEntry) {
     let by_uid = entry.path.is_empty() && !entry.uid.is_empty();
     let rel = entry_rel(ui, entry);
@@ -442,6 +460,24 @@ fn load_details_extras(ui: &Rc<Ui>, entry: &DirEntry) {
     });
 
     if entry.is_dir {
+        let req = if by_uid {
+            Request::FolderSizeByUid {
+                uid: entry.uid.clone(),
+            }
+        } else {
+            Request::FolderSize { path: rel }
+        };
+        let rx = spawn_request(ui.dirs.control_socket(), req);
+        let (ui_c, uid) = (ui.clone(), entry.uid.clone());
+        glib::spawn_future_local(async move {
+            let text = match rx.recv().await {
+                Ok(Ok(Response::FolderSize { size, items })) => folder_size_summary(size, items),
+                _ => gettext("Couldn't load the size"),
+            };
+            if details_showing(&ui_c, &uid) {
+                ui_c.details.details.size_row.set_subtitle(&text);
+            }
+        });
         return;
     }
     let req = if by_uid {
@@ -488,6 +524,18 @@ pub(crate) fn sharing_summary(people: usize, link: bool) -> String {
     }
 }
 
+/// "1.2 GiB · 340 items": what a folder holds, as Proton Drive counts it.
+pub(crate) fn folder_size_summary(size: u64, items: u64) -> String {
+    // Translators: {size} is a size such as "1.2 GiB"; {n} counts the files
+    // and folders inside a folder.
+    ngettext_f(
+        "{size} · {n} item",
+        "{size} · {n} items",
+        items,
+        &[("size", &human_bytes(size))],
+    )
+}
+
 /// "3 versions · latest 2 Sep 2026".
 pub(crate) fn versions_summary(items: &[RevisionInfo]) -> String {
     let latest = items.iter().map(|r| r.created).max();
@@ -536,6 +584,12 @@ pub(crate) fn selected_entry(ui: &Rc<Ui>) -> Option<DirEntry> {
 mod tests {
     use super::*;
 
+    #[test]
+    fn folder_size_summary_reads_size_and_item_count() {
+        assert_eq!(folder_size_summary(0, 0), "0 bytes · 0 items");
+        assert_eq!(folder_size_summary(2048, 1), "2.0 KiB · 1 item");
+    }
+
     #[test]
     fn sharing_summary_names_people_and_link() {
         assert_eq!(sharing_summary(0, false), "Only you");

crates/pdfs-gui/src/app/widgets/file_list.rs

@@ -132,8 +132,13 @@ impl FileList {
                 // and the grid collapses to a single column. Allowing a mid-word
                 // break is what keeps the two-line-then-ellipsis budget below
                 // enforceable for *every* name rather than only the ones that
-                // happen to have spaces.
+                // happen to have spaces. Pango marks such a break with a hyphen
+                // that is not in the name ("SteamSetup.e-xe"); a file name is
+                // not prose, so break it bare, as Nautilus does.
+                let no_hyphens = gtk4::pango::AttrList::new();
+                no_hyphens.insert(gtk4::pango::AttrInt::new_insert_hyphens(false));
                 let label = gtk4::Label::builder()
+                    .attributes(&no_hyphens)
                     .ellipsize(gtk4::pango::EllipsizeMode::End)
                     .justify(gtk4::Justification::Center)
                     .max_width_chars(13)

crates/pdfs-gui/src/app/widgets/menu.rs

@@ -61,6 +61,18 @@ impl ActionMenu {
         self
     }
 
+    /// A greyed-out check item showing `active`, for a state the user cannot
+    /// change from here.
+    pub(crate) fn locked_toggle(&mut self, label: &str, active: bool) -> &mut Self {
+        let name = self.next_action();
+        let action = gio::SimpleAction::new_stateful(&name, None, &active.to_variant());
+        action.set_enabled(false);
+        self.group.add_action(&action);
+        self.section
+            .append(Some(label), Some(&format!("menu.{name}")));
+        self
+    }
+
     /// Close the current section; the next item starts a new one below a
     /// separator. An empty section is skipped, so callers can end a group of
     /// conditional items unconditionally.
@@ -128,20 +140,34 @@ impl ActionMenu {
     }
 }
 
-/// Where a menu opened over `anchor` should live in the widget tree: the
-/// outermost grid or list view around it, or `anchor` itself. CSS descendant
-/// selectors reach through a popover to its parent, and themes style the
-/// insides of list items (`gridview > child box { margin: 12px }` in
-/// Catppuccin); a menu parented to a tile picks those rules up and puts a wide
-/// margin around every section. Under the view itself it is no item's child.
+/// Where a menu opened over `anchor` should live in the widget tree.
+///
+/// Not inside a list item: CSS descendant selectors reach through a popover to
+/// its parent, and themes style the insides of list items (`gridview > child
+/// box { margin: 12px }` in Catppuccin); a menu parented to a tile picks those
+/// rules up and puts a wide margin around every section. So the search starts
+/// at the outermost grid or list view around `anchor`.
+///
+/// Not on a widget without a layout manager either: a popover is sized and
+/// placed again when its parent's layout manager allocates it. The list views
+/// and `ScrolledWindow` have none, so a menu parented there kept the size it was
+/// first given, often too small, and opened scrolling. The host is the first
+/// widget from there up that has one.
 fn popover_host(anchor: &gtk4::Widget) -> gtk4::Widget {
-    let mut host = anchor.clone();
+    let mut start = anchor.clone();
     let mut widget = anchor.parent();
     while let Some(w) = widget {
         widget = w.parent();
         if w.is::<gtk4::GridView>() || w.is::<gtk4::ListView>() || w.is::<gtk4::ColumnView>() {
-            host = w;
+            start = w;
         }
     }
-    host
+    let mut host = Some(start.clone());
+    while let Some(w) = host {
+        if w.layout_manager().is_some() {
+            return w;
+        }
+        host = w.parent();
+    }
+    start
 }