version bumped to 1.2

Version bump in b93e41e updated Cargo.toml only, so the release
workflow's tag/manifest/PKGBUILD agreement check failed on v1.1.1.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01BEWKS8smdPfLMZacgDXjAR

Cargo.lock

@@ -3518,7 +3518,7 @@ checksum = "35fb2e5f958ec131621fdd531e9fc186ed768cbe395337403ae56c17a74c68ec"
 
 [[package]]
 name = "pdfs-cli"
-version = "1.1.0"
+version = "1.2.0"
 dependencies = [
  "anyhow",
  "clap 4.6.4",
@@ -3533,7 +3533,7 @@ dependencies = [
 
 [[package]]
 name = "pdfs-core"
-version = "1.1.0"
+version = "1.2.0"
 dependencies = [
  "directories",
  "ignore",
@@ -3553,7 +3553,7 @@ dependencies = [
 
 [[package]]
 name = "pdfs-fuse"
-version = "1.1.0"
+version = "1.2.0"
 dependencies = [
  "fuser",
  "image",
@@ -3569,7 +3569,7 @@ dependencies = [
 
 [[package]]
 name = "pdfs-gui"
-version = "1.1.0"
+version = "1.2.0"
 dependencies = [
  "anyhow",
  "async-channel",
@@ -3830,9 +3830,9 @@ dependencies = [
 
 [[package]]
 name = "proton-drive-rs"
-version = "0.2.2"
+version = "0.3.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "692610fbead83735a0415d9d068c1e9b467b12cce013ea19b3063f05206ce3d6"
+checksum = "a02afd5a53ecbf0e1ea18f3102e7b99e5ad61977ee0709bd214279b2376e0077"
 dependencies = [
  "async-trait",
  "base64",
@@ -3857,9 +3857,9 @@ dependencies = [
 
 [[package]]
 name = "proton-sdk"
-version = "0.2.2"
+version = "0.3.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "6b3f2ad9cd1ba69b67cbafcaf7c159b3a200162a3c518b1bc7e25df837343b41"
+checksum = "46b5f84f0c33ac7a19b0131e971e7a17f10f12d6dc6df64c3b9dda7f37aa35bb"
 dependencies = [
  "aes-gcm 0.11.0",
  "async-trait",

Cargo.toml

@@ -3,15 +3,15 @@ resolver = "2"
 members = ["crates/pdfs-core", "crates/pdfs-fuse", "crates/pdfs-cli", "crates/pdfs-gui"]
 
 [workspace.package]
-version = "1.1.0"
+version = "1.2.0"
 edition = "2024"
 license = "MIT"
 authors = ["Nils Pukropp <contact@narl.io>"]
 rust-version = "1.96"
 
 [workspace.dependencies]
-proton-sdk = { version = "0.2.2" }
-proton-drive-rs = { version = "0.2.2" }
+proton-sdk = { version = "0.3.1" }
+proton-drive-rs = { version = "0.3.1" }
 
 # Internal crates.
 pdfs-core = { path = "crates/pdfs-core" }

crates/pdfs-cli/src/main.rs

@@ -13,7 +13,7 @@ use pdfs_core::auth;
 use pdfs_core::cache::ContentCache;
 use pdfs_core::config::AppDirs;
 use pdfs_core::control::{
-    ErrorKind, RefreshScope, Request as CtlRequest, Response as CtlResponse,
+    ErrorKind, MountKind, RefreshScope, Request as CtlRequest, Response as CtlResponse,
     RestoreItem as CtlRestoreItem, ShareEntryKind, SyncPhase, pending_summary,
 };
 use pdfs_core::db::Db;
@@ -28,7 +28,7 @@ struct Cli {
     /// Emit machine-readable JSON instead of formatted text.
     ///
     /// Applies to the query commands (`status`, `ls`, `pins`, `sync list`,
-    /// `devices list`, `transfers`, `activity`, `cache inspect`). Commands that
+    /// `devices list`, `locations`, `transfers`, `activity`, `cache inspect`). Commands that
     /// perform an action keep their human output — a script that needs to know
     /// whether one succeeded has the exit code.
     #[arg(long, global = true)]
@@ -105,6 +105,8 @@ enum Command {
     Logout,
     /// Show account login state, and mount status if a daemon is running.
     Status,
+    /// List every local Proton Drive location.
+    Locations,
     /// Mount Proton Drive at the given (or default) path. Blocks until unmounted.
     Mount {
         /// Mountpoint; defaults to ~/ProtonDrive.
@@ -507,6 +509,7 @@ fn main() -> Result<()> {
         Command::Login { username } => cmd_login(username),
         Command::Logout => cmd_logout(),
         Command::Status => cmd_status(),
+        Command::Locations => cmd_locations(),
         Command::Mount { mountpoint } => cmd_mount(mountpoint),
         Command::Daemon { mountpoint } => cmd_daemon(mountpoint),
         Command::Pin { path } => cmd_pin(path),
@@ -1201,6 +1204,45 @@ fn cmd_status() -> Result<()> {
     Ok(())
 }
 
+fn cmd_locations() -> Result<()> {
+    let response = control_request(CtlRequest::ListLocations)?;
+    if emit_json(&response)? {
+        return Ok(());
+    }
+    match response {
+        CtlResponse::Locations { items } if items.is_empty() => {
+            println!("No Proton Drive locations.");
+        }
+        CtlResponse::Locations { items } => {
+            for location in items {
+                let kind = match &location.kind {
+                    MountKind::MyFiles => "My Files".to_string(),
+                    MountKind::Device { sync_folder_id } => {
+                        format!("Device folder {sync_folder_id}")
+                    }
+                    MountKind::Shared { .. } => "Shared folder".to_string(),
+                };
+                let mode = match location.pending_mode {
+                    Some(pending) => format!("{} -> {pending}", location.mode),
+                    None => location.mode.to_string(),
+                };
+                let mounted = if location.mounted {
+                    "mounted"
+                } else {
+                    "not mounted"
+                };
+                println!(
+                    "{kind}: {} ({mode}, {}, {}, {mounted})",
+                    location.local_path, location.access, location.state
+                );
+            }
+        }
+        CtlResponse::Error { message, kind } => bail!("{}", cli_error(kind, &message)),
+        other => bail!("unexpected response: {other:?}"),
+    }
+    Ok(())
+}
+
 fn cmd_mount(mountpoint: Option<PathBuf>) -> Result<()> {
     mount_once(mountpoint)?;
     Ok(())

crates/pdfs-core/src/access.rs

@@ -0,0 +1,108 @@
+//! Effective access carried by mounted Drive nodes.
+
+use proton_drive_rs::MemberRole;
+
+/// Effective write access for a node in a mounted tree.
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+pub enum Access {
+    Owner,
+    Editor,
+    Viewer,
+    Unknown,
+}
+
+impl Access {
+    pub fn writable(self) -> bool {
+        matches!(self, Self::Owner | Self::Editor)
+    }
+
+    pub(crate) fn as_db_str(self) -> &'static str {
+        match self {
+            Self::Owner => "owner",
+            Self::Editor => "editor",
+            Self::Viewer => "viewer",
+            Self::Unknown => "unknown",
+        }
+    }
+
+    pub(crate) fn from_db_str(value: &str) -> Option<Self> {
+        match value {
+            "owner" => Some(Self::Owner),
+            "editor" => Some(Self::Editor),
+            "viewer" => Some(Self::Viewer),
+            "unknown" => Some(Self::Unknown),
+            _ => None,
+        }
+    }
+}
+
+/// Resolve a share root's effective access from its exact membership role.
+///
+/// Owned trees fail open. A share whose role is absent or unrecognised fails
+/// closed. Descendants normally inherit directly at intern time; `Inherited`
+/// exists for the explicit wire role and therefore returns `parent`.
+pub fn access_for(role: Option<MemberRole>, parent: Access, under_share: bool) -> Access {
+    match role {
+        Some(MemberRole::Viewer) => Access::Viewer,
+        Some(MemberRole::Editor | MemberRole::Admin) => Access::Editor,
+        Some(MemberRole::Inherited) => parent,
+        None if under_share => Access::Viewer,
+        None => Access::Owner,
+    }
+}
+
+/// POSIX permission bits advertised for a mounted node.
+pub fn perm_bits(is_dir: bool, access: Access) -> u16 {
+    match (is_dir, access.writable()) {
+        (true, true) => 0o755,
+        (false, true) => 0o644,
+        (true, false) => 0o555,
+        (false, false) => 0o444,
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn access_for_covers_the_fail_open_and_fail_closed_table() {
+        for parent in [
+            Access::Owner,
+            Access::Editor,
+            Access::Viewer,
+            Access::Unknown,
+        ] {
+            assert_eq!(access_for(None, parent, false), Access::Owner);
+            assert_eq!(access_for(None, parent, true), Access::Viewer);
+            assert_eq!(
+                access_for(Some(MemberRole::Viewer), parent, true),
+                Access::Viewer
+            );
+            assert_eq!(
+                access_for(Some(MemberRole::Editor), parent, true),
+                Access::Editor
+            );
+            assert_eq!(
+                access_for(Some(MemberRole::Admin), parent, true),
+                Access::Editor
+            );
+            assert_eq!(
+                access_for(Some(MemberRole::Inherited), parent, true),
+                parent
+            );
+        }
+    }
+
+    #[test]
+    fn permission_bits_follow_effective_access() {
+        for writable in [Access::Owner, Access::Editor] {
+            assert_eq!(perm_bits(true, writable), 0o755);
+            assert_eq!(perm_bits(false, writable), 0o644);
+        }
+        for read_only in [Access::Viewer, Access::Unknown] {
+            assert_eq!(perm_bits(true, read_only), 0o555);
+            assert_eq!(perm_bits(false, read_only), 0o444);
+        }
+    }
+}

crates/pdfs-core/src/cache.rs

@@ -17,6 +17,7 @@
 //! [`Node`]: proton_drive_rs::Node
 
 use std::collections::{BTreeMap, HashSet};
+use std::fmt;
 use std::io::{Read, Seek, SeekFrom};
 use std::path::{Path, PathBuf};
 use std::sync::Arc;
@@ -28,10 +29,11 @@ use serde::{Deserialize, Serialize};
 use sha2::{Digest, Sha256};
 
 use crate::db::{CacheEntryInput, Db};
-use crate::error::Result;
+use crate::error::{Error, Result};
 
 /// `cache_entries.kind` tag for whole-file content blobs.
 const KIND_BLOB: &str = "blob";
+static STAGING_N: AtomicU64 = AtomicU64::new(0);
 /// `cache_entries.kind` tag for on-demand block-cache chunks.
 const KIND_BLOCK: &str = "block";
 /// `cache_entries.kind` tag for cached thumbnails.
@@ -169,6 +171,35 @@ pub struct Baseline {
     pub revision_id: Option<String>,
 }
 
+/// A denied-write rescue that retained the bytes but could not fully publish
+/// their recovery metadata.
+#[derive(Debug)]
+pub struct PreserveWriteError {
+    /// The actual path that still contains the accepted bytes.
+    pub surviving_path: PathBuf,
+    /// The recovery metadata that still describes those bytes, when one could
+    /// be made durable. Callers must never clear this after an error.
+    pub marker_path: Option<PathBuf>,
+    error: Error,
+}
+
+impl fmt::Display for PreserveWriteError {
+    fn fmt(&self, formatter: &mut fmt::Formatter<'_>) -> fmt::Result {
+        write!(
+            formatter,
+            "{} (bytes retained at {})",
+            self.error,
+            self.surviving_path.display()
+        )
+    }
+}
+
+impl std::error::Error for PreserveWriteError {
+    fn source(&self) -> Option<&(dyn std::error::Error + 'static)> {
+        Some(&self.error)
+    }
+}
+
 /// Content cache rooted at a directory, with a sibling pin-registry file.
 pub struct ContentCache {
     /// Directory holding `<key>` blobs and `<key>.meta` tags.
@@ -225,6 +256,18 @@ pub struct ContentCache {
 }
 
 impl ContentCache {
+    fn staging_path(&self, meta: &StagedWrite) -> PathBuf {
+        // The uid goes in the name so a staged file can be tied back to its node
+        // without a database; `/` in a uid would otherwise open a path.
+        let safe_uid = meta.uid.replace(['/', '\\'], "_");
+        self.staging_dir.join(format!(
+            "{}-{}-{}",
+            safe_uid,
+            now_millis(),
+            STAGING_N.fetch_add(1, Ordering::Relaxed)
+        ))
+    }
+
     /// Open (and create) a cache under `content_dir`, with the pin registry at
     /// `pins_path` and a `max_bytes` size cap (`0` = unlimited). Both parent
     /// directories are created if missing. `db` is the shared metadata database
@@ -910,16 +953,7 @@ impl ContentCache {
     pub fn stage_write(&self, meta: &StagedWrite, scratch: &Path) -> Result<PathBuf> {
         use std::io::Write as _;
 
-        static N: AtomicU64 = AtomicU64::new(0);
-        // The uid goes in the name so a staged file can be tied back to its node
-        // without a database; `/` in a uid would otherwise open a path.
-        let safe_uid = meta.uid.replace(['/', '\\'], "_");
-        let path = self.staging_dir.join(format!(
-            "{}-{}-{}",
-            safe_uid,
-            now_millis(),
-            N.fetch_add(1, Ordering::Relaxed)
-        ));
+        let path = self.staging_path(meta);
         let copied = if let Err(e) = std::fs::rename(scratch, &path) {
             if e.kind() != std::io::ErrorKind::CrossesDevices {
                 return Err(e.into());
@@ -949,6 +983,154 @@ impl ContentCache {
         Ok(path)
     }
 
+    /// Preserve accepted bytes which cannot be queued.
+    ///
+    /// Scratch and staging normally share a filesystem, so the normal path is
+    /// an atomic rename. If that is impossible, the source first receives a
+    /// durable recovery marker and remains in place until a copied destination,
+    /// its sidecar, and the staging directory are all synced.
+    pub fn preserve_write(
+        &self,
+        meta: &StagedWrite,
+        scratch: &Path,
+    ) -> std::result::Result<PathBuf, PreserveWriteError> {
+        let path = self.staging_path(meta);
+        self.preserve_write_at(meta, scratch, &path)
+    }
+
+    fn preserve_write_at(
+        &self,
+        meta: &StagedWrite,
+        scratch: &Path,
+        path: &Path,
+    ) -> std::result::Result<PathBuf, PreserveWriteError> {
+        use std::io::Write as _;
+
+        let retained = |surviving_path: &Path, error: Error| {
+            let adjacent = Self::scratch_sidecar(surviving_path);
+            let source = Self::scratch_sidecar(scratch);
+            let marker_path = [adjacent, source].into_iter().find(|path| path.is_file());
+            PreserveWriteError {
+                surviving_path: surviving_path.to_path_buf(),
+                marker_path,
+                error,
+            }
+        };
+        // If rename cannot happen, this marker is what lets the next open move
+        // the still-authoritative source into recovery instead of deleting it.
+        let marker_result = self.mark_scratch_durable(scratch, meta);
+        let side = path.with_extension("json");
+        let side_tmp = path.with_extension("json.tmp");
+        let publish_sidecar = || -> Result<()> {
+            let mut side_file = std::fs::OpenOptions::new()
+                .write(true)
+                .create_new(true)
+                .open(&side_tmp)?;
+            side_file.write_all(&serde_json::to_vec_pretty(meta)?)?;
+            side_file.sync_all()?;
+            drop(side_file);
+            std::fs::rename(&side_tmp, &side)?;
+            std::fs::File::open(&self.staging_dir)?.sync_all()?;
+            Ok(())
+        };
+
+        match std::fs::rename(scratch, path) {
+            Ok(()) => {
+                if let Err(error) = std::fs::File::open(path).and_then(|file| file.sync_all()) {
+                    if std::fs::rename(path, scratch).is_ok() {
+                        if !Self::scratch_sidecar(scratch).is_file() {
+                            let _ = self.mark_scratch_durable(scratch, meta);
+                        }
+                        let _ =
+                            std::fs::File::open(&self.scratch_dir).and_then(|dir| dir.sync_all());
+                        return Err(retained(scratch, error.into()));
+                    }
+                    return Err(retained(path, error.into()));
+                }
+                let scratch_side = Self::scratch_sidecar(scratch);
+                let side_result = if marker_result.is_ok() {
+                    std::fs::rename(&scratch_side, &side)
+                        .map_err(Error::from)
+                        .and_then(|()| {
+                            std::fs::File::open(&self.staging_dir)?
+                                .sync_all()
+                                .map_err(Error::from)
+                        })
+                } else {
+                    publish_sidecar()
+                };
+                if let Err(error) = side_result {
+                    let _ = std::fs::remove_file(&side_tmp);
+                    // Publication did not complete. Put the blob back beside
+                    // the source marker so startup recovery still has a
+                    // reconstructable pair, rather than an unexplained staging
+                    // blob and a marker whose source vanished.
+                    if std::fs::rename(path, scratch).is_ok() {
+                        if !Self::scratch_sidecar(scratch).is_file() {
+                            let _ = self.mark_scratch_durable(scratch, meta);
+                        }
+                        let _ =
+                            std::fs::File::open(&self.scratch_dir).and_then(|dir| dir.sync_all());
+                        return Err(retained(scratch, error));
+                    }
+                    return Err(retained(path, error));
+                }
+                Ok(path.to_path_buf())
+            }
+            Err(rename_error) => {
+                let source_marked =
+                    marker_result.is_ok() || Self::scratch_sidecar(scratch).exists();
+                if let Err(marker_error) = marker_result {
+                    tracing::warn!(
+                        error = %marker_error,
+                        path = %scratch.display(),
+                        "could not mark rescue source durable before copy fallback"
+                    );
+                }
+                if let Err(error) = std::fs::copy(scratch, path) {
+                    if !source_marked {
+                        let recovery = self.recovery_dir.join(
+                            path.file_name()
+                                .unwrap_or_else(|| std::ffi::OsStr::new("denied-write")),
+                        );
+                        if std::fs::rename(scratch, &recovery).is_ok() {
+                            let _ = std::fs::File::open(&self.recovery_dir)
+                                .and_then(|dir| dir.sync_all());
+                            return Err(retained(
+                                &recovery,
+                                Error::Other(format!(
+                                    "rename failed ({rename_error}); copy fallback failed ({error})"
+                                )),
+                            ));
+                        }
+                    }
+                    return Err(retained(
+                        scratch,
+                        Error::Other(format!(
+                            "rename failed ({rename_error}); copy fallback failed ({error})"
+                        )),
+                    ));
+                }
+                if let Err(error) = std::fs::File::open(path).and_then(|file| file.sync_all()) {
+                    let surviving = if source_marked { scratch } else { path };
+                    return Err(retained(surviving, error.into()));
+                }
+                if let Err(error) = publish_sidecar() {
+                    let _ = std::fs::remove_file(&side_tmp);
+                    let surviving = if source_marked { scratch } else { path };
+                    return Err(retained(surviving, error));
+                }
+                // Deliberately last: fallback never removes its marked source
+                // until destination publication is complete.
+                if let Err(error) = std::fs::remove_file(scratch) {
+                    return Err(retained(path, error.into()));
+                }
+                self.clear_scratch_durable(scratch);
+                Ok(path.to_path_buf())
+            }
+        }
+    }
+
     /// Drop a staged blob and its sidecar, once its bytes are safely on the
     /// remote (or the op that owned them has been superseded). Best effort:
     /// leftovers cost disk, while failing here would strand a drained op.
@@ -1906,6 +2088,92 @@ mod tests {
         );
     }
 
+    fn preservation_meta() -> StagedWrite {
+        StagedWrite {
+            uid: uid("preserved").to_string(),
+            len: 14,
+            base_size: 0,
+            base_mtime: 100,
+            authored: vec![(0, 14)],
+            complete: true,
+            based_on: None,
+        }
+    }
+
+    #[test]
+    fn orphan_preservation_publishes_exact_bytes_then_removes_source() {
+        use std::io::Write as _;
+
+        let (c, _dir) = cache();
+        let (mut file, scratch) = c.create_scratch().unwrap();
+        file.write_all(b"accepted bytes").unwrap();
+        file.sync_all().unwrap();
+        drop(file);
+
+        let preserved = c.preserve_write(&preservation_meta(), &scratch).unwrap();
+
+        assert!(!scratch.exists());
+        assert_eq!(std::fs::read(&preserved).unwrap(), b"accepted bytes");
+        let sidecar: StagedWrite =
+            serde_json::from_slice(&std::fs::read(preserved.with_extension("json")).unwrap())
+                .unwrap();
+        let expected = preservation_meta();
+        assert_eq!(sidecar.uid, expected.uid);
+        assert_eq!(sidecar.len, expected.len);
+        assert_eq!(sidecar.authored, expected.authored);
+        assert_eq!(sidecar.complete, expected.complete);
+    }
+
+    #[test]
+    fn orphan_preservation_sidecar_failure_reports_surviving_blob_across_reopen() {
+        use std::io::Write as _;
+
+        let (c, dir) = cache();
+        let (mut file, scratch) = c.create_scratch().unwrap();
+        file.write_all(b"only surviving copy").unwrap();
+        file.sync_all().unwrap();
+        drop(file);
+
+        let destination = c.staging_dir.join("forced-preservation-failure");
+        let side = destination.with_extension("json");
+        std::fs::create_dir(&side).unwrap();
+
+        let error = c
+            .preserve_write_at(&preservation_meta(), &scratch, &destination)
+            .unwrap_err();
+        assert_eq!(error.surviving_path, scratch);
+        assert!(
+            scratch.exists(),
+            "failed sidecar publication must roll the blob back beside its marker"
+        );
+        assert_eq!(
+            std::fs::read(&error.surviving_path).unwrap(),
+            b"only surviving copy"
+        );
+        assert_eq!(
+            error.marker_path,
+            Some(ContentCache::scratch_sidecar(&scratch))
+        );
+        assert!(
+            side.is_dir(),
+            "the induced sidecar failure remains observable"
+        );
+
+        let content = dir.path().join("content");
+        let pins = dir.path().join("pins-reopen.json");
+        drop(c);
+        let reopened =
+            ContentCache::open(content, pins, 0, Arc::new(Db::open_in_memory().unwrap())).unwrap();
+        let recovered = reopened.recovered_writes();
+        assert_eq!(recovered.len(), 1);
+        assert_eq!(
+            std::fs::read(&recovered[0].0).unwrap(),
+            b"only surviving copy"
+        );
+        assert_eq!(recovered[0].1.uid, preservation_meta().uid);
+        drop(reopened);
+    }
+
     /// A2: `fsync(2)` promises the bytes survive a crash, but queueing happens
     /// at `release`. A scratch file marked durable must therefore outlive the
     /// open that clears the scratch directory — and an unmarked one must not,

crates/pdfs-core/src/control.rs

@@ -14,6 +14,7 @@ use serde::{Deserialize, Serialize};
 
 use crate::cache::Pin;
 use crate::error::Result;
+pub use crate::mounts::{MountAccess, MountKind, MountMode, MountSpec};
 
 /// Cap on the *write* half of a round-trip. A crashed daemon can leave its
 /// listening socket in the kernel (e.g. as a `<defunct>` zombie): `connect`
@@ -194,6 +195,11 @@ pub enum Request {
     /// it invalidates, it does not fetch.
     Refresh { scope: RefreshScope },
 
+    // ---- locations --------------------------------------------------------
+    /// List every local Proton Drive location. Replies with
+    /// [`Response::Locations`].
+    ListLocations,
+
     // ---- devices ----------------------------------------------------------
     /// List the account's registered devices. Replies with [`Response::Devices`].
     ListDevices,
@@ -240,9 +246,20 @@ pub enum Request {
         role: String,
         message: Option<String>,
     },
+    /// The by-uid twin of [`Request::ShareNode`], for nodes proven to belong to
+    /// an on-demand or mirror device location. This is a distinct variant so an
+    /// older daemon rejects it instead of ignoring `uid` and acting on `path`.
+    ShareNodeByUid {
+        uid: String,
+        emails: Vec<String>,
+        role: String,
+        message: Option<String>,
+    },
     /// List the members, pending invitations and public link of the node at
     /// mountpoint-relative `path`. Replies with [`Response::Share`].
     ListShare { path: String },
+    /// The by-uid twin of [`Request::ListShare`].
+    ListShareByUid { uid: String },
     /// Change the role of a share entry (member or pending invitation) on the node
     /// at `path`. `id` and `kind` identify the entry (from [`Response::Share`]).
     /// Replies with [`Response::Ok`].
@@ -252,6 +269,13 @@ pub enum Request {
         kind: ShareEntryKind,
         role: String,
     },
+    /// The by-uid twin of [`Request::UpdateShareRole`].
+    UpdateShareRoleByUid {
+        uid: String,
+        id: String,
+        kind: ShareEntryKind,
+        role: String,
+    },
     /// Remove a share entry (member, pending Proton invite, or external invite)
     /// from the node at `path`. Replies with [`Response::Ok`].
     RemoveShareEntry {
@@ -259,6 +283,12 @@ pub enum Request {
         id: String,
         kind: ShareEntryKind,
     },
+    /// The by-uid twin of [`Request::RemoveShareEntry`].
+    RemoveShareEntryByUid {
+        uid: String,
+        id: String,
+        kind: ShareEntryKind,
+    },
     /// Create a public link on the node at `path`. `role` is "viewer" or "editor";
     /// `password` optionally adds a custom password; `expires` is an optional Unix
     /// expiry. Replies with [`Response::PublicLink`] (carrying the shareable URL).
@@ -268,9 +298,18 @@ pub enum Request {
         password: Option<String>,
         expires: Option<i64>,
     },
+    /// The by-uid twin of [`Request::CreatePublicLink`].
+    CreatePublicLinkByUid {
+        uid: String,
+        role: String,
+        password: Option<String>,
+        expires: Option<i64>,
+    },
     /// Remove the public link `id` from the node at `path`. Replies with
     /// [`Response::Ok`].
     RemovePublicLink { path: String, id: String },
+    /// The by-uid twin of [`Request::RemovePublicLink`].
+    RemovePublicLinkByUid { uid: String, id: String },
 
     // ---- shared by me -----------------------------------------------------
     /// List the nodes I have shared with others — collaborative shares that still
@@ -1094,6 +1133,8 @@ pub enum Response {
     },
     /// The account's devices (reply to [`Request::ListDevices`]).
     Devices { items: Vec<DeviceInfo> },
+    /// Every local Proton Drive location (reply to [`Request::ListLocations`]).
+    Locations { items: Vec<MountSpec> },
     /// This device's synced folders (reply to [`Request::ListSyncFolders`]).
     SyncFolders { items: Vec<SyncFolderInfo> },
     /// Folders offered for restore (reply to [`Request::ListRestorableFolders`]).
@@ -1541,6 +1582,7 @@ mod tests {
     #[test]
     fn sharing_requests_roundtrip() {
         let reqs = [
+            Request::ListLocations,
             Request::ListDevices,
             Request::RenameDevice {
                 uid: "dev-1".into(),
@@ -1580,28 +1622,58 @@ mod tests {
                 role: "editor".into(),
                 message: Some("hi".into()),
             },
+            Request::ShareNodeByUid {
+                uid: "vol~link".into(),
+                emails: vec!["x@proton.me".into(), "y@example.com".into()],
+                role: "editor".into(),
+                message: Some("hi".into()),
+            },
             Request::ListShare { path: "a/b".into() },
+            Request::ListShareByUid {
+                uid: "vol~link".into(),
+            },
             Request::UpdateShareRole {
                 path: "a/b".into(),
                 id: "mid-1".into(),
                 kind: ShareEntryKind::Member,
                 role: "admin".into(),
             },
+            Request::UpdateShareRoleByUid {
+                uid: "vol~link".into(),
+                id: "mid-1".into(),
+                kind: ShareEntryKind::Member,
+                role: "admin".into(),
+            },
             Request::RemoveShareEntry {
                 path: "a/b".into(),
                 id: "iid-1".into(),
                 kind: ShareEntryKind::ExternalInvite,
             },
+            Request::RemoveShareEntryByUid {
+                uid: "vol~link".into(),
+                id: "iid-1".into(),
+                kind: ShareEntryKind::ExternalInvite,
+            },
             Request::CreatePublicLink {
                 path: "a/b".into(),
                 role: "viewer".into(),
                 password: Some("pw".into()),
                 expires: Some(1_700_000_000),
             },
+            Request::CreatePublicLinkByUid {
+                uid: "vol~link".into(),
+                role: "viewer".into(),
+                password: Some("pw".into()),
+                expires: Some(1_700_000_000),
+            },
             Request::RemovePublicLink {
                 path: "a/b".into(),
                 id: "url-1".into(),
             },
+            Request::RemovePublicLinkByUid {
+                uid: "vol~link".into(),
+                id: "url-1".into(),
+            },
             Request::ListSharedByMe,
             Request::ListActivity { limit: 100 },
             Request::ListSharedWithMe,
@@ -1635,6 +1707,323 @@ mod tests {
         }
     }
 
+    #[test]
+    fn locations_response_roundtrips_typed_mounts() {
+        let response = Response::Locations {
+            items: vec![
+                MountSpec {
+                    id: 1,
+                    kind: MountKind::MyFiles,
+                    local_path: "/home/me/ProtonDrive".into(),
+                    root_uid: "vol~root".into(),
+                    root_share_id: "share-main".into(),
+                    mode: MountMode::OnDemand,
+                    access: MountAccess::Rw,
+                    state: "idle".into(),
+                    last_sync: 0,
+                    pending_mode: None,
+                    mounted: true,
+                    progress: None,
+                },
+                MountSpec {
+                    id: 2,
+                    kind: MountKind::Device { sync_folder_id: 7 },
+                    local_path: "/home/me/Work".into(),
+                    root_uid: "device-vol~work".into(),
+                    root_share_id: "device-share".into(),
+                    mode: MountMode::Mirror,
+                    access: MountAccess::Rw,
+                    state: "syncing".into(),
+                    last_sync: 42,
+                    pending_mode: Some(MountMode::OnDemand),
+                    mounted: false,
+                    progress: None,
+                },
+                MountSpec {
+                    id: 3,
+                    kind: MountKind::Shared {
+                        share_root_uid: "shared-vol~root".into(),
+                    },
+                    local_path: "/home/me/Shared".into(),
+                    root_uid: "shared-vol~root".into(),
+                    root_share_id: "shared-share".into(),
+                    mode: MountMode::Unknown,
+                    access: MountAccess::Ro,
+                    state: "error".into(),
+                    last_sync: 0,
+                    pending_mode: Some(MountMode::Unknown),
+                    mounted: false,
+                    progress: Some(SyncProgress {
+                        phase: SyncPhase::Applying,
+                        done: 2,
+                        total: 5,
+                        current: "report.pdf".into(),
+                    }),
+                },
+            ],
+        };
+        let wire = serde_json::to_string(&response).unwrap();
+        assert!(!wire.contains('\n'), "wire form must be a single line");
+        assert!(wire.contains(r#""mode":"ondemand""#));
+        assert!(wire.contains(r#""kind":"shared""#));
+        assert!(wire.contains(r#""access":"ro""#));
+        assert!(wire.contains(r#""mode":"unknown""#));
+        let back: Response = serde_json::from_str(&wire).unwrap();
+        match back {
+            Response::Locations { items } => {
+                assert_eq!(items.len(), 3);
+                assert!(matches!(
+                    items[1].kind,
+                    MountKind::Device { sync_folder_id: 7 }
+                ));
+                assert_eq!(items[1].pending_mode, Some(MountMode::OnDemand));
+                assert!(matches!(
+                    &items[2].kind,
+                    MountKind::Shared { share_root_uid }
+                        if share_root_uid == "shared-vol~root"
+                ));
+                assert_eq!(items[2].access, MountAccess::Ro);
+                assert_eq!(items[2].mode, MountMode::Unknown);
+                assert_eq!(items[2].pending_mode, Some(MountMode::Unknown));
+                let progress = items[2].progress.as_ref().unwrap();
+                assert_eq!(progress.phase, SyncPhase::Applying);
+                assert_eq!((progress.done, progress.total), (2, 5));
+            }
+            other => panic!("unexpected response: {other:?}"),
+        }
+    }
+
+    #[test]
+    fn legacy_daemons_reject_list_locations_cleanly() {
+        #[allow(dead_code)]
+        #[derive(serde::Deserialize)]
+        enum LegacyLocationRequest {
+            ListSyncFolders,
+        }
+
+        let wire = serde_json::to_string(&Request::ListLocations).unwrap();
+        assert!(
+            serde_json::from_str::<LegacyLocationRequest>(&wire).is_err(),
+            "an old daemon must reject ListLocations instead of interpreting another request"
+        );
+    }
+
+    #[test]
+    fn path_share_requests_keep_their_existing_wire_shape() {
+        let cases = [
+            (
+                Request::ShareNode {
+                    path: "a/b".into(),
+                    emails: vec!["x@example.com".into()],
+                    role: "viewer".into(),
+                    message: None,
+                },
+                r#"{"ShareNode":{"path":"a/b","emails":["x@example.com"],"role":"viewer","message":null}}"#,
+            ),
+            (
+                Request::ListShare { path: "a/b".into() },
+                r#"{"ListShare":{"path":"a/b"}}"#,
+            ),
+            (
+                Request::UpdateShareRole {
+                    path: "a/b".into(),
+                    id: "member".into(),
+                    kind: ShareEntryKind::Member,
+                    role: "editor".into(),
+                },
+                r#"{"UpdateShareRole":{"path":"a/b","id":"member","kind":"Member","role":"editor"}}"#,
+            ),
+            (
+                Request::RemoveShareEntry {
+                    path: "a/b".into(),
+                    id: "invite".into(),
+                    kind: ShareEntryKind::ProtonInvite,
+                },
+                r#"{"RemoveShareEntry":{"path":"a/b","id":"invite","kind":"ProtonInvite"}}"#,
+            ),
+            (
+                Request::CreatePublicLink {
+                    path: "a/b".into(),
+                    role: "viewer".into(),
+                    password: None,
+                    expires: None,
+                },
+                r#"{"CreatePublicLink":{"path":"a/b","role":"viewer","password":null,"expires":null}}"#,
+            ),
+            (
+                Request::RemovePublicLink {
+                    path: "a/b".into(),
+                    id: "link".into(),
+                },
+                r#"{"RemovePublicLink":{"path":"a/b","id":"link"}}"#,
+            ),
+        ];
+
+        for (request, expected) in cases {
+            assert_eq!(serde_json::to_string(&request).unwrap(), expected);
+            assert!(
+                !expected.contains("\"uid\""),
+                "path variants must never acquire an optional uid"
+            );
+        }
+    }
+
+    #[test]
+    fn by_uid_share_requests_are_distinct_wire_variants() {
+        let cases = [
+            (
+                Request::ShareNodeByUid {
+                    uid: "vol~link".into(),
+                    emails: vec!["x@example.com".into()],
+                    role: "viewer".into(),
+                    message: None,
+                },
+                "ShareNodeByUid",
+            ),
+            (
+                Request::ListShareByUid {
+                    uid: "vol~link".into(),
+                },
+                "ListShareByUid",
+            ),
+            (
+                Request::UpdateShareRoleByUid {
+                    uid: "vol~link".into(),
+                    id: "member".into(),
+                    kind: ShareEntryKind::Member,
+                    role: "editor".into(),
+                },
+                "UpdateShareRoleByUid",
+            ),
+            (
+                Request::RemoveShareEntryByUid {
+                    uid: "vol~link".into(),
+                    id: "invite".into(),
+                    kind: ShareEntryKind::ProtonInvite,
+                },
+                "RemoveShareEntryByUid",
+            ),
+            (
+                Request::CreatePublicLinkByUid {
+                    uid: "vol~link".into(),
+                    role: "viewer".into(),
+                    password: None,
+                    expires: None,
+                },
+                "CreatePublicLinkByUid",
+            ),
+            (
+                Request::RemovePublicLinkByUid {
+                    uid: "vol~link".into(),
+                    id: "link".into(),
+                },
+                "RemovePublicLinkByUid",
+            ),
+        ];
+
+        for (request, variant) in cases {
+            let wire = serde_json::to_string(&request).unwrap();
+            let object = serde_json::from_str::<serde_json::Value>(&wire)
+                .unwrap()
+                .as_object()
+                .cloned()
+                .unwrap();
+            assert_eq!(object.len(), 1);
+            assert!(object.contains_key(variant));
+            let decoded = serde_json::from_str::<Request>(&wire).unwrap();
+            let decoded_uid = match &decoded {
+                Request::ShareNodeByUid { uid, .. }
+                | Request::ListShareByUid { uid }
+                | Request::UpdateShareRoleByUid { uid, .. }
+                | Request::RemoveShareEntryByUid { uid, .. }
+                | Request::CreatePublicLinkByUid { uid, .. }
+                | Request::RemovePublicLinkByUid { uid, .. } => uid,
+                other => panic!("decoded into the wrong dispatch variant: {other:?}"),
+            };
+            assert_eq!(decoded_uid, "vol~link");
+            assert_eq!(serde_json::to_string(&decoded).unwrap(), wire);
+        }
+    }
+
+    #[test]
+    fn legacy_daemons_reject_new_by_uid_variants() {
+        #[allow(dead_code)]
+        #[derive(serde::Deserialize)]
+        enum LegacyShareRequest {
+            ShareNode {
+                path: String,
+                emails: Vec<String>,
+                role: String,
+                message: Option<String>,
+            },
+            ListShare {
+                path: String,
+            },
+            UpdateShareRole {
+                path: String,
+                id: String,
+                kind: ShareEntryKind,
+                role: String,
+            },
+            RemoveShareEntry {
+                path: String,
+                id: String,
+                kind: ShareEntryKind,
+            },
+            CreatePublicLink {
+                path: String,
+                role: String,
+                password: Option<String>,
+                expires: Option<i64>,
+            },
+            RemovePublicLink {
+                path: String,
+                id: String,
+            },
+        }
+
+        let requests = [
+            Request::ShareNodeByUid {
+                uid: "vol~link".into(),
+                emails: Vec::new(),
+                role: "viewer".into(),
+                message: None,
+            },
+            Request::ListShareByUid {
+                uid: "vol~link".into(),
+            },
+            Request::UpdateShareRoleByUid {
+                uid: "vol~link".into(),
+                id: "member".into(),
+                kind: ShareEntryKind::Member,
+                role: "viewer".into(),
+            },
+            Request::RemoveShareEntryByUid {
+                uid: "vol~link".into(),
+                id: "member".into(),
+                kind: ShareEntryKind::Member,
+            },
+            Request::CreatePublicLinkByUid {
+                uid: "vol~link".into(),
+                role: "viewer".into(),
+                password: None,
+                expires: None,
+            },
+            Request::RemovePublicLinkByUid {
+                uid: "vol~link".into(),
+                id: "link".into(),
+            },
+        ];
+
+        for request in requests {
+            let wire = serde_json::to_string(&request).unwrap();
+            assert!(
+                serde_json::from_str::<LegacyShareRequest>(&wire).is_err(),
+                "an old daemon must reject {wire}, never reinterpret it as a path request"
+            );
+        }
+    }
+
     /// A daemon built before `kind` existed sends `Error` without the field.
     /// It must still parse, and land on the class that promises the least.
     #[test]

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

@@ -77,10 +77,12 @@ const REPORTED_TABLES: &[&str] = &[
     "trash",
     "device",
     "sync_folder",
+    "mount",
     "sync_entry",
     "pending_op",
     "activity",
     "local_files",
+    "share_access",
 ];
 
 impl Db {

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

@@ -9,7 +9,7 @@ use super::Db;
 use crate::Result;
 
 /// Current schema version. Bump on every forward migration added below.
-pub(super) const SCHEMA_VERSION: i64 = 16;
+pub(super) const SCHEMA_VERSION: i64 = 18;
 
 impl Db {
     pub(super) fn migrate(&self) -> Result<()> {
@@ -89,6 +89,12 @@ impl Db {
         if current < 16 {
             tx.execute_batch(MIGRATION_V16)?;
         }
+        if current < 17 {
+            tx.execute_batch(MIGRATION_V17)?;
+        }
+        if current < 18 {
+            tx.execute_batch(MIGRATION_V18)?;
+        }
         tx.execute(
             "INSERT INTO sync_state (key, value) VALUES ('schema_version', ?1)
              ON CONFLICT(key) DO UPDATE SET value = excluded.value",
@@ -411,3 +417,58 @@ CREATE INDEX IF NOT EXISTS idx_local_files_name_nocase
   ON local_files(name COLLATE NOCASE);
 INSERT INTO local_fts(local_fts) VALUES('rebuild');
 ";
+
+/// Schema v17: effective access for roots shared with this account. The role is
+/// persisted separately from `nodes.node_json` so a cold/offline mount can
+/// enforce the last known permission even when the SDK cannot refresh metadata.
+const MIGRATION_V17: &str = "
+CREATE TABLE share_access (
+  root_uid TEXT PRIMARY KEY,
+  access   TEXT NOT NULL
+           CHECK (access IN ('owner', 'editor', 'viewer', 'unknown'))
+);
+";
+
+/// Schema v18: unified location presentation. Device rows carry only their
+/// `sync_folder` identity; reads join all device state from that authoritative
+/// table. The trigger projects future folders, while the foreign key removes a
+/// presentation row with its sync folder.
+const MIGRATION_V18: &str = "
+CREATE TABLE mount (
+  id              INTEGER PRIMARY KEY,
+  kind            TEXT NOT NULL
+                  CHECK (kind IN ('myfiles', 'device', 'shared')),
+  sync_folder_id  INTEGER REFERENCES sync_folder(id) ON DELETE CASCADE,
+  share_root_uid  TEXT,
+  local_path      TEXT NOT NULL DEFAULT '',
+  root_uid        TEXT NOT NULL DEFAULT '',
+  root_share_id   TEXT NOT NULL DEFAULT '',
+  mode            TEXT NOT NULL DEFAULT 'unknown',
+  access          TEXT NOT NULL DEFAULT 'rw'
+                  CHECK (access IN ('rw', 'ro')),
+  CHECK (
+    (kind = 'myfiles' AND sync_folder_id IS NULL AND share_root_uid IS NULL)
+    OR
+    (kind = 'device' AND sync_folder_id IS NOT NULL AND share_root_uid IS NULL)
+    OR
+    (kind = 'shared' AND sync_folder_id IS NULL AND share_root_uid IS NOT NULL)
+  )
+);
+
+CREATE UNIQUE INDEX mount_myfiles
+  ON mount(kind) WHERE kind = 'myfiles';
+CREATE UNIQUE INDEX mount_device
+  ON mount(sync_folder_id) WHERE kind = 'device';
+CREATE UNIQUE INDEX mount_shared
+  ON mount(share_root_uid) WHERE kind = 'shared';
+
+INSERT INTO mount (kind, sync_folder_id)
+SELECT 'device', id FROM sync_folder;
+
+CREATE TRIGGER mount_sync_folder_insert
+AFTER INSERT ON sync_folder
+BEGIN
+  INSERT OR IGNORE INTO mount (kind, sync_folder_id)
+  VALUES ('device', NEW.id);
+END;
+";

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

@@ -27,10 +27,12 @@ mod devices;
 mod local;
 mod maintenance;
 mod migrations;
+mod mounts;
 mod nodes;
 mod ops;
 mod photos;
 mod pins;
+mod share_access;
 mod state;
 mod sync;
 mod trash;
@@ -40,10 +42,10 @@ pub use cache::CacheEntryInput;
 pub use devices::StoredDevice;
 pub use local::LocalFileHit;
 pub use maintenance::{DbStats, VacuumOutcome};
-pub use nodes::{SearchHit, StoredNode};
+pub use nodes::{PublishedSharedRoot, SearchHit, StoredNode};
 pub use ops::{
     AttachedBlob, LOCAL_VOLUME, OP_CREATE, OP_MKDIR, OP_RENAME, OP_REVISION, OP_TRASH, PARK_UNTIL,
-    PendingCounts, PendingOp, op_supersedes,
+    PendingCounts, PendingOp, RenameMeta, op_supersedes,
 };
 pub use photos::{StoredPhoto, THUMB_HAVE, THUMB_NONE, THUMB_UNKNOWN};
 pub use sync::{StoredSyncEntry, StoredSyncFolder};
@@ -109,6 +111,10 @@ impl Db {
     #[cfg(test)]
     pub fn open_in_memory() -> Result<Self> {
         let conn = Connection::open_in_memory()?;
+        // Keep relational behavior identical to `open`: V18 relies on the
+        // `mount.sync_folder_id` cascade, and SQLite disables foreign keys per
+        // connection unless explicitly enabled.
+        conn.pragma_update(None, "foreign_keys", "ON")?;
         let db = Self {
             conn: Mutex::new(conn),
         };

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

@@ -0,0 +1,178 @@
+//! Unified mount/location presentation rows.
+//!
+//! A device row stores only its `sync_folder` identity. Its path, remote root,
+//! mode, state, pending mode, and last-sync timestamp are selected from
+//! `sync_folder`, which remains the authoritative sync-engine table.
+
+use rusqlite::params;
+
+use super::Db;
+use crate::mounts::{MountAccess, MountKind, MountMode, MountSpec};
+use crate::{Error, Result};
+
+impl Db {
+    /// Project the configured primary mount into the presentation table.
+    ///
+    /// `root_share_id` is optional because an offline startup may only have the
+    /// cached root node. A previously learned share id is retained only when it
+    /// belongs to the same root uid.
+    pub fn mount_upsert_my_files(
+        &self,
+        local_path: &str,
+        root_uid: &str,
+        root_share_id: Option<&str>,
+    ) -> Result<i64> {
+        let mut conn = self.conn.lock();
+        let tx = conn.transaction()?;
+        let updated = tx.execute(
+            "UPDATE mount
+                SET local_path = ?1,
+                    root_share_id = CASE
+                        WHEN root_uid = ?2
+                          THEN COALESCE(NULLIF(?3, ''), root_share_id)
+                        ELSE COALESCE(?3, '')
+                    END,
+                    root_uid = ?2,
+                    mode = 'ondemand',
+                    access = 'rw'
+              WHERE kind = 'myfiles'",
+            params![local_path, root_uid, root_share_id],
+        )?;
+        let id = if updated == 0 {
+            tx.execute(
+                "INSERT INTO mount
+                    (kind, local_path, root_uid, root_share_id, mode, access)
+                 VALUES ('myfiles', ?1, ?2, COALESCE(?3, ''), 'ondemand', 'rw')",
+                params![local_path, root_uid, root_share_id],
+            )?;
+            tx.last_insert_rowid()
+        } else {
+            tx.query_row("SELECT id FROM mount WHERE kind = 'myfiles'", [], |row| {
+                row.get(0)
+            })?
+        };
+        tx.commit()?;
+        Ok(id)
+    }
+
+    /// Store a share id learned asynchronously, but only if the projection still
+    /// names the root it was resolved for.
+    pub fn mount_repair_my_files_share_id(
+        &self,
+        root_uid: &str,
+        root_share_id: &str,
+    ) -> Result<bool> {
+        let conn = self.conn.lock();
+        Ok(conn.execute(
+            "UPDATE mount
+                SET root_share_id = ?2
+              WHERE kind = 'myfiles'
+                AND root_uid = ?1",
+            params![root_uid, root_share_id],
+        )? > 0)
+    }
+
+    /// Every local location, with device fields joined from `sync_folder`.
+    pub fn mount_list(&self) -> Result<Vec<MountSpec>> {
+        let conn = self.conn.lock();
+        let mut stmt = conn.prepare(
+            "SELECT
+                 m.id,
+                 m.kind,
+                 m.sync_folder_id,
+                 m.share_root_uid,
+                 CASE WHEN m.kind = 'device' THEN sf.local_path ELSE m.local_path END,
+                 CASE WHEN m.kind = 'device' THEN sf.remote_uid ELSE m.root_uid END,
+                 CASE WHEN m.kind = 'device' THEN sf.remote_share_id ELSE m.root_share_id END,
+                 CASE WHEN m.kind = 'device' THEN sf.mode ELSE m.mode END,
+                 m.access,
+                 CASE WHEN m.kind = 'device' THEN sf.state ELSE 'idle' END,
+                 CASE WHEN m.kind = 'device' THEN sf.last_sync ELSE 0 END,
+                 CASE WHEN m.kind = 'device' THEN sf.pending_mode ELSE NULL END
+               FROM mount AS m
+               LEFT JOIN sync_folder AS sf ON sf.id = m.sync_folder_id
+              ORDER BY CASE m.kind
+                         WHEN 'myfiles' THEN 0
+                         WHEN 'device' THEN 1
+                         ELSE 2
+                       END,
+                       m.id",
+        )?;
+        let rows = stmt.query_map([], |row| {
+            Ok((
+                row.get::<_, i64>(0)?,
+                row.get::<_, String>(1)?,
+                row.get::<_, Option<i64>>(2)?,
+                row.get::<_, Option<String>>(3)?,
+                row.get::<_, String>(4)?,
+                row.get::<_, String>(5)?,
+                row.get::<_, String>(6)?,
+                row.get::<_, String>(7)?,
+                row.get::<_, String>(8)?,
+                row.get::<_, String>(9)?,
+                row.get::<_, i64>(10)?,
+                row.get::<_, Option<String>>(11)?,
+            ))
+        })?;
+
+        let mut mounts = Vec::new();
+        for row in rows {
+            let (
+                id,
+                kind,
+                sync_folder_id,
+                share_root_uid,
+                local_path,
+                root_uid,
+                root_share_id,
+                mode,
+                access,
+                state,
+                last_sync,
+                pending_mode,
+            ) = row?;
+            let kind = match kind.as_str() {
+                "myfiles" => MountKind::MyFiles,
+                "device" => MountKind::Device {
+                    sync_folder_id: sync_folder_id.ok_or_else(|| {
+                        Error::Other(format!("mount row {id} has no sync_folder_id"))
+                    })?,
+                },
+                "shared" => MountKind::Shared {
+                    share_root_uid: share_root_uid.ok_or_else(|| {
+                        Error::Other(format!("mount row {id} has no share_root_uid"))
+                    })?,
+                },
+                other => {
+                    return Err(Error::Other(format!(
+                        "mount row {id} has unknown kind {other:?}"
+                    )));
+                }
+            };
+            let access = match access.as_str() {
+                "rw" => MountAccess::Rw,
+                "ro" => MountAccess::Ro,
+                other => {
+                    return Err(Error::Other(format!(
+                        "mount row {id} has unknown access {other:?}"
+                    )));
+                }
+            };
+            mounts.push(MountSpec {
+                id,
+                kind,
+                local_path,
+                root_uid,
+                root_share_id,
+                mode: MountMode::from(mode.as_str()),
+                access,
+                state,
+                last_sync,
+                pending_mode: pending_mode.as_deref().map(MountMode::from),
+                mounted: false,
+                progress: None,
+            });
+        }
+        Ok(mounts)
+    }
+}

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

@@ -1,11 +1,13 @@
 //! Node rows: the persisted mirror of the remote tree, plus the trigram
 //! full-text index over names and paths that backs `Request::Search`.
 
-use rusqlite::{OptionalExtension, params};
+use std::collections::HashSet;
+
+use rusqlite::{OptionalExtension, Transaction, params};
 
 use super::Db;
-use crate::Result;
-use proton_drive_rs::proton_sdk::ids::NodeUid;
+use crate::{Access, Result};
+use proton_drive_rs::proton_sdk::ids::{LinkId, NodeUid, VolumeId};
 use proton_drive_rs::{Node, NodeKind};
 
 use super::utils::{TRIGRAM_MIN, collect_pairs, like_escape, pair, path_of};
@@ -22,6 +24,11 @@ pub struct SearchHit {
     pub path: String,
 }
 
+pub struct PublishedSharedRoot {
+    pub node: Node,
+    pub access: Access,
+}
+
 impl Db {
     pub fn upsert_node(&self, node: &Node) -> Result<()> {
         self.upsert_nodes(std::slice::from_ref(node))
@@ -42,87 +49,188 @@ impl Db {
         let mut conn = self.conn.lock();
         let tx = conn.transaction()?;
         for node in nodes {
-            let json = serde_json::to_string(node)?;
-            let uid = node.uid.to_string();
-            tx.execute(
-                "INSERT INTO nodes
-                   (uid, parent_uid, name, is_dir, size, mtime, trashed, node_json)
-                 VALUES (?1, ?2, ?3, ?4, ?5, ?6, ?7, ?8)
-                 ON CONFLICT(uid) DO UPDATE SET
-                   parent_uid = excluded.parent_uid,
-                   name       = excluded.name,
-                   is_dir     = excluded.is_dir,
-                   size       = excluded.size,
-                   mtime      = excluded.mtime,
-                   trashed    = excluded.trashed,
-                   node_json  = excluded.node_json",
-                params![
-                    uid,
-                    node.parent_uid.as_ref().map(|u| u.to_string()),
-                    node.name,
-                    node.is_folder() as i64,
-                    node_size(node),
-                    node.modification_time,
-                    node.trashed as i64,
-                    json,
-                ],
-            )?;
-            // FTS5 has no UPSERT, so refresh the row by delete-then-insert.
-            // Trashed nodes are kept out of the index entirely so they never
-            // surface in search results.
-            //
-            // Keyed by the node's rowid, never by its uid: the uid is not an
-            // indexed FTS column, so deleting by it scans the entire index once
-            // per node written (B12). The rowid is stable across the upsert
-            // above — `ON CONFLICT DO UPDATE` keeps the existing row — so it is
-            // the same key before and after.
-            let rowid: i64 = tx.query_row(
-                "SELECT rowid FROM nodes WHERE uid = ?1",
-                params![uid],
-                |row| row.get(0),
-            )?;
-            // A folder rename/move changes every descendant's searchable path.
-            // Refresh the affected subtree, while retaining efficient rowid
-            // deletes for the overwhelmingly common one-file case.
-            let mut affected = vec![rowid];
-            if node.is_folder() {
-                let mut stmt = tx.prepare(
-                    "WITH RECURSIVE descendants(rowid, uid) AS (
-                       SELECT rowid, uid FROM nodes WHERE parent_uid = ?1
-                       UNION ALL
-                       SELECT n.rowid, n.uid FROM nodes n
-                         JOIN descendants d ON n.parent_uid = d.uid
-                     ) SELECT rowid FROM descendants",
-                )?;
-                for descendant in stmt.query_map(params![uid], |row| row.get(0))? {
-                    affected.push(descendant?);
-                }
-            }
-            for affected_rowid in affected {
-                tx.execute(
-                    "DELETE FROM nodes_fts WHERE rowid = ?1",
-                    params![affected_rowid],
-                )?;
-                let indexed: Option<(String, String)> = tx
-                    .query_row(
-                        "SELECT name, uid FROM nodes WHERE rowid = ?1 AND trashed = 0",
-                        params![affected_rowid],
-                        |row| Ok((row.get(0)?, row.get(1)?)),
-                    )
-                    .optional()?;
-                if let Some((name, indexed_uid)) = indexed {
-                    let path = path_of(&tx, &indexed_uid)?;
-                    tx.execute(
-                        "INSERT INTO nodes_fts (rowid, name, path) VALUES (?1, ?2, ?3)",
-                        params![affected_rowid, name, path],
-                    )?;
-                }
-            }
+            upsert_node_tx(&tx, node)?;
         }
         tx.commit()?;
         Ok(())
     }
 
+    /// Return visible direct children without consulting the parent's `listed`
+    /// flag. Synthetic shared listings use this to serve the last completed
+    /// snapshot while offline, including after a live event expired its TTL.
+    pub fn visible_children(&self, parent: &NodeUid) -> Result<Vec<Node>> {
+        let conn = self.conn.lock();
+        let mut stmt = conn.prepare(
+            "SELECT node_json FROM nodes
+              WHERE parent_uid = ?1 AND trashed = 0 AND node_json IS NOT NULL
+              ORDER BY name, uid",
+        )?;
+        let rows = stmt.query_map([parent.to_string()], |row| row.get::<_, String>(0))?;
+        let mut nodes = Vec::new();
+        for row in rows {
+            nodes.push(serde_json::from_str(&row?)?);
+        }
+        Ok(nodes)
+    }
+
+    /// Atomically publish one completed `Shared with me` root listing.
+    ///
+    /// Roots absent from `accepted` and every persisted descendant are
+    /// tombstoned, not deleted. Accepted roots omitted from materialization keep
+    /// their visible snapshot but are downgraded to Viewer until membership is
+    /// verified again. Both cases preserve queued operations and staged writes.
+    pub fn publish_shared_roots(
+        &self,
+        parent: &NodeUid,
+        accepted: &[NodeUid],
+        roots: &[PublishedSharedRoot],
+    ) -> Result<Vec<NodeUid>> {
+        let parent = parent.to_string();
+        let present: HashSet<String> = accepted.iter().map(NodeUid::to_string).collect();
+        let materialized: HashSet<String> = roots
+            .iter()
+            .map(|published| published.node.uid.to_string())
+            .collect();
+        let mut conn = self.conn.lock();
+        let tx = conn.transaction()?;
+
+        let existing = direct_child_uids_tx(&tx, &parent)?;
+        let removed: Vec<String> = existing
+            .into_iter()
+            .filter(|uid| !present.contains(uid))
+            .collect();
+
+        for published in roots {
+            if !present.contains(&published.node.uid.to_string()) {
+                continue;
+            }
+            upsert_node_tx(&tx, &published.node)?;
+            upsert_share_access_tx(&tx, &published.node.uid.to_string(), published.access)?;
+        }
+        for uid in present.difference(&materialized) {
+            upsert_share_access_tx(&tx, uid, Access::Viewer)?;
+        }
+        for root in &removed {
+            tombstone_subtree_tx(&tx, root)?;
+            upsert_share_access_tx(&tx, root, Access::Viewer)?;
+        }
+        tx.execute(
+            "UPDATE nodes SET listed = 1 WHERE uid = ?1",
+            params![parent],
+        )?;
+        tx.commit()?;
+
+        Ok(removed
+            .into_iter()
+            .filter_map(|uid| parse_node_uid(&uid))
+            .collect())
+    }
+
+    /// Atomically withdraw a deleted foreign subtree and deny stale handles.
+    ///
+    /// Node rows and queued operations remain so retries and staged writes keep
+    /// their references. FTS and completed-listing state are withdrawn for the
+    /// whole subtree, and the deleted UID becomes a fail-closed authority.
+    pub fn tombstone_foreign_subtree(&self, uid: &NodeUid) -> Result<()> {
+        let uid = uid.to_string();
+        let mut conn = self.conn.lock();
+        let tx = conn.transaction()?;
+        tombstone_subtree_tx(&tx, &uid)?;
+        upsert_share_access_tx(&tx, &uid, Access::Viewer)?;
+        tx.commit()?;
+        Ok(())
+    }
+
+    /// Publish a completed foreign-folder listing from its authoritative UID
+    /// list and the subset that materialized successfully. Accepted-but-omitted
+    /// children retain their previous snapshot; only absent UIDs are tombstoned.
+    pub fn publish_foreign_children(
+        &self,
+        parent: &NodeUid,
+        accepted: &[NodeUid],
+        materialized: &[Node],
+    ) -> Result<Vec<NodeUid>> {
+        let parent = parent.to_string();
+        let present: HashSet<String> = accepted.iter().map(NodeUid::to_string).collect();
+        let mut conn = self.conn.lock();
+        let tx = conn.transaction()?;
+        let removed: Vec<String> = direct_child_uids_tx(&tx, &parent)?
+            .into_iter()
+            .filter(|uid| !present.contains(uid))
+            .collect();
+        for node in materialized {
+            if present.contains(&node.uid.to_string()) {
+                upsert_node_tx(&tx, node)?;
+            }
+        }
+        for uid in &removed {
+            tombstone_subtree_tx(&tx, uid)?;
+        }
+        tx.execute(
+            "UPDATE nodes SET listed = 1 WHERE uid = ?1",
+            params![parent],
+        )?;
+        tx.commit()?;
+        Ok(removed
+            .into_iter()
+            .filter_map(|uid| parse_node_uid(&uid))
+            .collect())
+    }
+
+    /// Atomically publish the synthetic root's pinned name, node/FTS state, and
+    /// Viewer authority.
+    ///
+    /// The pin is inserted last so any failure there rolls back the node and
+    /// its descendant FTS updates as well as the access row. Returning `false`
+    /// guarantees no write occurred, which keeps cached root lookups O(1).
+    pub fn publish_virtual_root(&self, pinned_name_key: &str, node: &Node) -> Result<bool> {
+        let uid = node.uid.to_string();
+        let desired_parent = node.parent_uid.as_ref().map(NodeUid::to_string);
+        let mut conn = self.conn.lock();
+        let tx = conn.transaction()?;
+        let pinned_name: Option<String> = tx
+            .query_row(
+                "SELECT value FROM sync_state WHERE key = ?1",
+                params![pinned_name_key],
+                |row| row.get(0),
+            )
+            .optional()?;
+        let stored: Option<(Option<String>, String, i64, i64)> = tx
+            .query_row(
+                "SELECT parent_uid, name, is_dir, trashed FROM nodes WHERE uid = ?1",
+                params![uid],
+                |row| Ok((row.get(0)?, row.get(1)?, row.get(2)?, row.get(3)?)),
+            )
+            .optional()?;
+        let access: Option<String> = tx
+            .query_row(
+                "SELECT access FROM share_access WHERE root_uid = ?1",
+                params![uid],
+                |row| row.get(0),
+            )
+            .optional()?;
+        let unchanged = stored.is_some_and(|(parent, name, is_dir, trashed)| {
+            parent == desired_parent
+                && name == node.name
+                && is_dir == 1
+                && trashed == node.trashed as i64
+        }) && access.as_deref() == Some(Access::Viewer.as_db_str())
+            && pinned_name.is_some();
+        if unchanged {
+            tx.commit()?;
+            return Ok(false);
+        }
+        upsert_share_access_tx(&tx, &uid, Access::Viewer)?;
+        upsert_node_tx(&tx, node)?;
+        tx.execute(
+            "INSERT INTO sync_state (key, value) VALUES (?1, ?2)
+             ON CONFLICT(key) DO NOTHING",
+            params![pinned_name_key, node.name],
+        )?;
+        tx.commit()?;
+        Ok(true)
+    }
+
     /// Drop a node row (delete or trash from the hot cache). Children rows are
     /// not cascaded here; the daemon forgets a whole subtree node-by-node.
     pub fn delete_node(&self, uid: &NodeUid) -> Result<()> {
@@ -148,6 +256,32 @@ impl Db {
         Ok(())
     }
 
+    /// Atomically retire a landed trash operation and its retained authority.
+    ///
+    /// Queued trash keeps the node row so drain-time permission checks can
+    /// resolve its shared-tree access. Removing the op first could resurrect
+    /// that row after a crash; removing the row first could strand a now
+    /// unauthorizable op. One transaction closes both windows.
+    pub fn complete_trash_op(&self, op_id: i64, uid: &NodeUid) -> Result<()> {
+        let uid = uid.to_string();
+        let mut conn = self.conn.lock();
+        let tx = conn.transaction()?;
+        let rowid: Option<i64> = tx
+            .query_row(
+                "SELECT rowid FROM nodes WHERE uid = ?1",
+                params![uid],
+                |row| row.get(0),
+            )
+            .optional()?;
+        tx.execute("DELETE FROM nodes WHERE uid = ?1", params![uid])?;
+        if let Some(rowid) = rowid {
+            tx.execute("DELETE FROM nodes_fts WHERE rowid = ?1", params![rowid])?;
+        }
+        tx.execute("DELETE FROM pending_op WHERE id = ?1", params![op_id])?;
+        tx.commit()?;
+        Ok(())
+    }
+
     /// Check if a folder node has any non-trashed children in the database.
     pub fn has_children(&self, parent_uid: &NodeUid) -> Result<bool> {
         let uid_str = parent_uid.to_string();
@@ -387,6 +521,168 @@ impl Db {
     // in sync on every store/read/evict, so it is authoritative for eviction.
 }
 
+fn upsert_node_tx(tx: &Transaction<'_>, node: &Node) -> Result<()> {
+    let json = serde_json::to_string(node)?;
+    let uid = node.uid.to_string();
+    tx.execute(
+        "INSERT INTO nodes
+           (uid, parent_uid, name, is_dir, size, mtime, trashed, node_json)
+         VALUES (?1, ?2, ?3, ?4, ?5, ?6, ?7, ?8)
+         ON CONFLICT(uid) DO UPDATE SET
+           parent_uid = excluded.parent_uid,
+           name       = excluded.name,
+           is_dir     = excluded.is_dir,
+           size       = excluded.size,
+           mtime      = excluded.mtime,
+           trashed    = excluded.trashed,
+           node_json  = excluded.node_json",
+        params![
+            uid,
+            node.parent_uid.as_ref().map(|u| u.to_string()),
+            node.name,
+            node.is_folder() as i64,
+            node_size(node),
+            node.modification_time,
+            node.trashed as i64,
+            json,
+        ],
+    )?;
+    // FTS5 has no UPSERT. Folder moves also change every descendant path, so
+    // refresh the whole affected subtree while keeping rowid deletes indexed.
+    let rowid: i64 = tx.query_row(
+        "SELECT rowid FROM nodes WHERE uid = ?1",
+        params![uid],
+        |row| row.get(0),
+    )?;
+    let mut affected = vec![rowid];
+    if node.is_folder() {
+        let mut stmt = tx.prepare(
+            "WITH RECURSIVE descendants(rowid, uid) AS (
+               SELECT rowid, uid FROM nodes WHERE parent_uid = ?1
+               UNION ALL
+               SELECT n.rowid, n.uid FROM nodes n
+                 JOIN descendants d ON n.parent_uid = d.uid
+             ) SELECT rowid FROM descendants",
+        )?;
+        for descendant in stmt.query_map(params![uid], |row| row.get(0))? {
+            affected.push(descendant?);
+        }
+    }
+    for affected_rowid in affected {
+        tx.execute(
+            "DELETE FROM nodes_fts WHERE rowid = ?1",
+            params![affected_rowid],
+        )?;
+        let indexed: Option<(String, String)> = tx
+            .query_row(
+                "SELECT name, uid FROM nodes WHERE rowid = ?1",
+                params![affected_rowid],
+                |row| Ok((row.get(0)?, row.get(1)?)),
+            )
+            .optional()?;
+        if let Some((name, indexed_uid)) = indexed
+            && node_is_indexable_tx(tx, &indexed_uid)?
+        {
+            let path = path_of(tx, &indexed_uid)?;
+            tx.execute(
+                "INSERT INTO nodes_fts (rowid, name, path) VALUES (?1, ?2, ?3)",
+                params![affected_rowid, name, path],
+            )?;
+        }
+    }
+    Ok(())
+}
+
+fn direct_child_uids_tx(tx: &Transaction<'_>, parent: &str) -> Result<Vec<String>> {
+    let mut stmt = tx.prepare("SELECT uid FROM nodes WHERE parent_uid = ?1")?;
+    let rows = stmt.query_map([parent], |row| row.get::<_, String>(0))?;
+    let mut uids = Vec::new();
+    for row in rows {
+        uids.push(row?);
+    }
+    Ok(uids)
+}
+
+fn node_is_indexable_tx(tx: &Transaction<'_>, uid: &str) -> Result<bool> {
+    let indexable: i64 = tx.query_row(
+        "WITH RECURSIVE ancestors(uid, parent_uid, trashed, path) AS (
+           SELECT uid, parent_uid, trashed, char(31) || uid || char(31)
+             FROM nodes WHERE uid = ?1
+           UNION ALL
+           SELECT n.uid, n.parent_uid, n.trashed,
+                  a.path || n.uid || char(31)
+             FROM ancestors a JOIN nodes n ON n.uid = a.parent_uid
+            WHERE instr(a.path, char(31) || n.uid || char(31)) = 0
+         )
+         SELECT CASE
+           WHEN COUNT(*) = 0 THEN 0
+           WHEN MAX(trashed) != 0 THEN 0
+           WHEN MAX(CASE WHEN parent_uid IS NULL THEN 1 ELSE 0 END) = 0 THEN 0
+           ELSE 1
+         END
+         FROM ancestors",
+        [uid],
+        |row| row.get(0),
+    )?;
+    Ok(indexable == 1)
+}
+
+fn tombstone_subtree_tx(tx: &Transaction<'_>, root_uid: &str) -> Result<()> {
+    let rows = {
+        let mut stmt = tx.prepare(
+            "WITH RECURSIVE subtree(rowid, uid, node_json) AS (
+               SELECT rowid, uid, node_json FROM nodes WHERE uid = ?1
+               UNION
+               SELECT n.rowid, n.uid, n.node_json FROM nodes n
+                 JOIN subtree s ON n.parent_uid = s.uid
+             )
+             SELECT rowid, uid, node_json FROM subtree",
+        )?;
+        let mapped = stmt.query_map([root_uid], |row| {
+            Ok((
+                row.get::<_, i64>(0)?,
+                row.get::<_, String>(1)?,
+                row.get::<_, Option<String>>(2)?,
+            ))
+        })?;
+        let mut rows = Vec::new();
+        for row in mapped {
+            rows.push(row?);
+        }
+        rows
+    };
+    for (rowid, uid, json) in rows {
+        let json = match json {
+            Some(json) => {
+                let mut node: Node = serde_json::from_str(&json)?;
+                node.trashed = true;
+                Some(serde_json::to_string(&node)?)
+            }
+            None => None,
+        };
+        tx.execute(
+            "UPDATE nodes SET trashed = 1, listed = 0, node_json = ?2 WHERE uid = ?1",
+            params![uid, json],
+        )?;
+        tx.execute("DELETE FROM nodes_fts WHERE rowid = ?1", [rowid])?;
+    }
+    Ok(())
+}
+
+fn upsert_share_access_tx(tx: &Transaction<'_>, uid: &str, access: Access) -> Result<()> {
+    tx.execute(
+        "INSERT INTO share_access (root_uid, access) VALUES (?1, ?2)
+         ON CONFLICT(root_uid) DO UPDATE SET access = excluded.access",
+        params![uid, access.as_db_str()],
+    )?;
+    Ok(())
+}
+
+fn parse_node_uid(value: &str) -> Option<NodeUid> {
+    let (volume, link) = value.split_once('~')?;
+    Some(NodeUid::new(VolumeId::from(volume), LinkId::from(link)))
+}
+
 /// Unique quoted character trigrams suitable for an FTS5 OR expression.
 pub(super) fn candidate_trigrams(query: &str) -> Vec<String> {
     let chars: Vec<char> = query.to_lowercase().chars().collect();

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

@@ -3,6 +3,7 @@
 //! order, so a child never drains before the parent that gives it a real uid.
 
 use rusqlite::{OptionalExtension, params};
+use serde::{Deserialize, Serialize};
 
 use super::Db;
 use crate::Result;
@@ -35,6 +36,16 @@ pub const OP_MKDIR: &str = "mkdir";
 /// that folder's own drain, exactly as for [`OP_CREATE`].
 pub const OP_RENAME: &str = "rename";
 
+/// Drain-time authority retained by a queued rename.
+///
+/// The optimistic local move rewrites the node's persisted ancestry to the
+/// destination immediately. Keeping the original parent here prevents that
+/// rewrite from erasing the shared tree that admitted the move.
+#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
+pub struct RenameMeta {
+    pub original_parent_uid: String,
+}
+
 /// The `kind` of a [`PendingOp`] that trashes a node the server knows about
 /// (offline.md Phase 3b).
 ///
@@ -127,6 +138,32 @@ pub struct AttachedBlob {
 }
 
 impl Db {
+    /// Whether a specific desired-state operation is still queued for a node.
+    pub fn has_pending_op(&self, uid: &str, kind: &str) -> Result<bool> {
+        let conn = self.conn.lock();
+        conn.query_row(
+            "SELECT EXISTS(
+                SELECT 1 FROM pending_op WHERE uid = ?1 AND kind = ?2
+             )",
+            params![uid, kind],
+            |row| row.get(0),
+        )
+        .map_err(Into::into)
+    }
+
+    /// Read an existing operation's metadata before a superseding enqueue.
+    pub fn pending_op_meta(&self, uid: &str, kind: &str) -> Result<Option<String>> {
+        let conn = self.conn.lock();
+        conn.query_row(
+            "SELECT meta_json FROM pending_op WHERE uid = ?1 AND kind = ?2",
+            params![uid, kind],
+            |row| row.get(0),
+        )
+        .optional()
+        .map(|value| value.flatten())
+        .map_err(Into::into)
+    }
+
     pub fn enqueue_op(&self, op: &PendingOp) -> Result<(i64, Option<String>)> {
         let mut conn = self.conn.lock();
         let tx = conn.transaction()?;
@@ -167,6 +204,50 @@ impl Db {
         Ok((id, superseded))
     }
 
+    /// Atomically replace every queued operation for `uid` and its queued
+    /// descendants with one remote trash intent.
+    ///
+    /// Staged blob paths are returned only after the transaction commits. A
+    /// failed trash insert therefore rolls the deletions back and leaves every
+    /// prior operation owning its bytes.
+    pub fn replace_ops_with_trash(
+        &self,
+        uid: &str,
+        name: &str,
+        created_at: i64,
+    ) -> Result<(i64, Vec<String>)> {
+        const SUBTREE: &str = "
+            WITH RECURSIVE doomed(uid) AS (
+              SELECT ?1
+              UNION
+              SELECT p.uid FROM pending_op p JOIN doomed d ON p.parent_uid = d.uid
+            )";
+        let mut conn = self.conn.lock();
+        let tx = conn.transaction()?;
+        let blobs: Vec<String> = {
+            let mut stmt = tx.prepare(&format!(
+                "{SUBTREE}
+                 SELECT blob_path FROM pending_op
+                 WHERE uid IN (SELECT uid FROM doomed) AND blob_path IS NOT NULL"
+            ))?;
+            let rows = stmt.query_map(params![uid], |row| row.get::<_, String>(0))?;
+            rows.collect::<std::result::Result<Vec<_>, _>>()?
+        };
+        tx.execute(
+            &format!("{SUBTREE} DELETE FROM pending_op WHERE uid IN (SELECT uid FROM doomed)"),
+            params![uid],
+        )?;
+        tx.execute(
+            "INSERT INTO pending_op
+               (kind, uid, parent_uid, name, blob_path, meta_json, created_at, next_attempt_at)
+             VALUES (?1, ?2, NULL, ?3, NULL, NULL, ?4, 0)",
+            params![OP_TRASH, uid, name, created_at],
+        )?;
+        let id = tx.last_insert_rowid();
+        tx.commit()?;
+        Ok((id, blobs))
+    }
+
     /// Point a queued create at the bytes that were just written to it, returning
     /// any blob it previously held so the caller can discard it.
     ///
@@ -509,4 +590,23 @@ impl Db {
         )?;
         Ok(())
     }
+
+    /// Defer a due operation without recording a failed remote attempt.
+    ///
+    /// Access checks happen before the drain calls Proton, so a locally denied
+    /// operation has not failed remotely and must not consume a retry. Preserve
+    /// the long-lived transient-create sentinel if this is ever called for one.
+    pub fn defer_op_without_attempt(&self, id: i64, next_attempt_at: i64) -> Result<()> {
+        let conn = self.conn.lock();
+        conn.execute(
+            "UPDATE pending_op
+             SET next_attempt_at = CASE
+                 WHEN next_attempt_at >= ?3 THEN next_attempt_at
+                 ELSE ?2
+             END
+             WHERE id = ?1",
+            params![id, next_attempt_at, PARK_UNTIL],
+        )?;
+        Ok(())
+    }
 }

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

@@ -0,0 +1,143 @@
+//! Persisted effective access for roots shared with this account.
+
+use std::collections::HashMap;
+
+use proton_drive_rs::proton_sdk::ids::{LinkId, NodeUid, VolumeId};
+use rusqlite::{OptionalExtension, params};
+
+use super::Db;
+use crate::{Access, Error, Result};
+
+impl Db {
+    /// Load the complete, deliberately small shared-root authority map.
+    ///
+    /// Mount state keeps this resident so ordinary node interning and subtree
+    /// propagation never turn into one SQLite query per inode. The database
+    /// remains the restart/offline authority and every explicit role change is
+    /// written through before this cache is updated.
+    pub fn all_share_access(&self) -> Result<HashMap<NodeUid, Access>> {
+        let conn = self.conn.lock();
+        let mut stmt = conn.prepare("SELECT root_uid, access FROM share_access")?;
+        let rows = stmt.query_map([], |row| {
+            Ok((row.get::<_, String>(0)?, row.get::<_, String>(1)?))
+        })?;
+        let mut access = HashMap::new();
+        for row in rows {
+            let (uid, value) = row?;
+            let (volume, link) = uid.split_once('~').ok_or_else(|| {
+                Error::Other(format!(
+                    "invalid shared-root uid {uid:?} stored in database"
+                ))
+            })?;
+            let access_value = Access::from_db_str(&value).ok_or_else(|| {
+                Error::Other(format!("invalid share access {value:?} stored for {uid}"))
+            })?;
+            access.insert(
+                NodeUid::new(VolumeId::from(volume), LinkId::from(link)),
+                access_value,
+            );
+        }
+        Ok(access)
+    }
+
+    /// Read the effective access recorded for a shared-tree root.
+    pub fn share_access(&self, uid: &NodeUid) -> Result<Option<Access>> {
+        let conn = self.conn.lock();
+        let value = conn
+            .query_row(
+                "SELECT access FROM share_access WHERE root_uid = ?1",
+                [uid.to_string()],
+                |row| row.get::<_, String>(0),
+            )
+            .optional()?;
+        value
+            .map(|value| {
+                Access::from_db_str(&value).ok_or_else(|| {
+                    Error::Other(format!("invalid share access {value:?} stored for {uid}"))
+                })
+            })
+            .transpose()
+    }
+
+    /// Insert or replace the effective access for a shared-tree root.
+    pub fn set_share_access(&self, uid: &NodeUid, access: Access) -> Result<()> {
+        let conn = self.conn.lock();
+        conn.execute(
+            "INSERT INTO share_access (root_uid, access) VALUES (?1, ?2)
+             ON CONFLICT(root_uid) DO UPDATE SET access = excluded.access",
+            params![uid.to_string(), access.as_db_str()],
+        )?;
+        Ok(())
+    }
+
+    /// Forget a shared-tree root's effective access.
+    pub fn delete_share_access(&self, uid: &NodeUid) -> Result<()> {
+        let conn = self.conn.lock();
+        conn.execute(
+            "DELETE FROM share_access WHERE root_uid = ?1",
+            [uid.to_string()],
+        )?;
+        Ok(())
+    }
+
+    /// Fail closed every persisted shared-tree authority.
+    ///
+    /// Owned and device trees have no row in `share_access`, so this only
+    /// affects roots already identified as shared with this account.
+    pub fn downgrade_all_share_access(&self) -> Result<usize> {
+        let conn = self.conn.lock();
+        Ok(conn.execute(
+            "UPDATE share_access SET access = 'viewer' WHERE access != 'viewer'",
+            [],
+        )?)
+    }
+
+    /// Resolve a persisted node's effective access through its nearest recorded
+    /// share root. `None` means the node itself is not persisted, which callers
+    /// must not treat as owned: stale handles need to fail closed.
+    pub fn effective_node_access(&self, uid: &NodeUid) -> Result<Option<Access>> {
+        let conn = self.conn.lock();
+        let exists: bool = conn.query_row(
+            "SELECT EXISTS(SELECT 1 FROM nodes WHERE uid = ?1)",
+            [uid.to_string()],
+            |row| row.get(0),
+        )?;
+        if !exists {
+            return Ok(None);
+        }
+        let value = conn
+            .query_row(
+                "WITH RECURSIVE ancestors(uid, parent_uid, depth, path) AS (
+                   SELECT uid, parent_uid, 0, char(31) || uid || char(31)
+                     FROM nodes WHERE uid = ?1
+                   UNION ALL
+                   SELECT a.parent_uid, n.parent_uid, a.depth + 1,
+                          a.path || a.parent_uid || char(31)
+                     FROM ancestors a
+                     LEFT JOIN nodes n ON n.uid = a.parent_uid
+                    WHERE a.parent_uid IS NOT NULL
+                      AND instr(
+                            a.path,
+                            char(31) || a.parent_uid || char(31)
+                          ) = 0
+                 )
+                 SELECT sa.access
+                   FROM ancestors a JOIN share_access sa ON sa.root_uid = a.uid
+                  ORDER BY a.depth ASC
+                  LIMIT 1",
+                [uid.to_string()],
+                |row| row.get::<_, String>(0),
+            )
+            .optional()?;
+        value
+            .map(|value| {
+                Access::from_db_str(&value).ok_or_else(|| {
+                    Error::Other(format!(
+                        "invalid effective share access {value:?} for {uid}"
+                    ))
+                })
+            })
+            .transpose()
+            .map(|access| Some(access.unwrap_or(Access::Owner)))
+    }
+}

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

@@ -115,14 +115,17 @@ impl Db {
         Ok(n > 0)
     }
 
-    /// Update a synced folder's mode (`mirror`/`ondemand`). The folder has
-    /// reached the mode it was asked for, so any queued request is satisfied and
-    /// cleared in the same write — a `pending_mode` outliving the switch it asked
-    /// for would have the engine try to apply it again on the next pass.
+    /// Update a synced folder's mode (`mirror`/`ondemand`). A queued request for
+    /// that mode is satisfied and cleared in the same write. An opposite pending
+    /// mode arrived after this transition started, so preserve it as the newer
+    /// last-request intent.
     pub fn sync_folder_set_mode(&self, id: i64, mode: &str) -> Result<()> {
         let conn = self.conn.lock();
         conn.execute(
-            "UPDATE sync_folder SET mode = ?2, pending_mode = NULL WHERE id = ?1",
+            "UPDATE sync_folder
+                SET mode = ?2,
+                    pending_mode = CASE WHEN pending_mode = ?2 THEN NULL ELSE pending_mode END
+              WHERE id = ?1",
             params![id, mode],
         )?;
         Ok(())
@@ -139,6 +142,18 @@ impl Db {
         Ok(())
     }
 
+    /// Withdraw a queued mode only if it is still the intent the caller
+    /// inspected. A newer request must survive an older settlement attempt.
+    pub fn sync_folder_clear_pending_mode_if(&self, id: i64, expected: &str) -> Result<bool> {
+        let conn = self.conn.lock();
+        let changed = conn.execute(
+            "UPDATE sync_folder SET pending_mode = NULL
+             WHERE id = ?1 AND pending_mode = ?2",
+            params![id, expected],
+        )?;
+        Ok(changed > 0)
+    }
+
     /// Update a synced folder's state and stamp `last_sync` to now.
     pub fn sync_folder_set_state(&self, id: i64, state: &str, last_sync: i64) -> Result<()> {
         let conn = self.conn.lock();
@@ -174,6 +189,28 @@ impl Db {
         Ok(map)
     }
 
+    /// Whether `uid` is represented by a mirror location.
+    ///
+    /// An on-demand location proves residency through its live inode state.
+    /// Mirror locations have no FUSE state, so their folder root comes from
+    /// `sync_folder` and descendants come from the last successful
+    /// `sync_entry` baseline.
+    pub fn mirror_contains_uid(&self, uid: &str) -> Result<bool> {
+        let conn = self.conn.lock();
+        conn.query_row(
+            "SELECT EXISTS(
+                 SELECT 1
+                   FROM sync_folder AS folder
+              LEFT JOIN sync_entry AS entry ON entry.folder_id = folder.id
+                  WHERE folder.mode = 'mirror'
+                    AND (folder.remote_uid = ?1 OR entry.remote_uid = ?1)
+             )",
+            params![uid],
+            |row| row.get(0),
+        )
+        .map_err(Into::into)
+    }
+
     /// Insert or replace one baseline row.
     pub fn sync_entry_upsert(&self, folder_id: i64, e: &StoredSyncEntry) -> Result<()> {
         let conn = self.conn.lock();

crates/pdfs-core/src/lib.rs

@@ -2,6 +2,7 @@
 //! identity, XDG paths, and the login/session/keyring layer that every
 //! front-end (CLI today, daemon + GUI later) shares.
 
+pub mod access;
 pub mod auth;
 pub mod cache;
 pub mod config;
@@ -9,12 +10,14 @@ pub mod control;
 pub mod db;
 pub mod error;
 pub mod localindex;
+pub mod mounts;
 pub mod profile;
 pub mod search;
 pub mod service;
 pub mod shell;
 pub mod syncignore;
 
+pub use access::{Access, access_for, perm_bits};
 pub use error::{CoreError, CoreResult, Error, Result};
 
 // Re-export the SDK surface downstream crates need, so they depend on

crates/pdfs-core/src/mounts.rs

@@ -0,0 +1,146 @@
+//! Unified presentation model for every local Proton Drive location.
+//!
+//! Device sync state remains owned by `sync_folder`; these types are the stable
+//! shape exposed to front-ends after that state is joined with the `mount`
+//! presentation table.
+
+use std::fmt;
+
+use serde::{Deserialize, Serialize};
+
+use crate::control::SyncProgress;
+
+/// How a location makes remote content available locally.
+#[derive(Serialize, Deserialize, Debug, Clone, Copy, PartialEq, Eq, Default)]
+#[serde(rename_all = "lowercase")]
+pub enum MountMode {
+    /// A full local copy reconciled in both directions.
+    Mirror,
+    /// A FUSE session that fetches content as it is accessed.
+    OnDemand,
+    /// A mode written by a newer client.
+    #[default]
+    #[serde(other)]
+    Unknown,
+}
+
+impl MountMode {
+    pub const fn as_str(self) -> &'static str {
+        match self {
+            Self::Mirror => "mirror",
+            Self::OnDemand => "ondemand",
+            Self::Unknown => "unknown",
+        }
+    }
+}
+
+impl From<&str> for MountMode {
+    fn from(value: &str) -> Self {
+        match value {
+            "mirror" => Self::Mirror,
+            "ondemand" => Self::OnDemand,
+            _ => Self::Unknown,
+        }
+    }
+}
+
+impl fmt::Display for MountMode {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        f.write_str(self.as_str())
+    }
+}
+
+/// Whether the location itself was declared writable.
+#[derive(Serialize, Deserialize, Debug, Clone, Copy, PartialEq, Eq)]
+#[serde(rename_all = "lowercase")]
+pub enum MountAccess {
+    Rw,
+    Ro,
+}
+
+impl MountAccess {
+    pub const fn as_str(self) -> &'static str {
+        match self {
+            Self::Rw => "rw",
+            Self::Ro => "ro",
+        }
+    }
+}
+
+impl fmt::Display for MountAccess {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        f.write_str(self.as_str())
+    }
+}
+
+/// What remote root a local location presents.
+#[derive(Serialize, Deserialize, Debug, Clone, PartialEq, Eq)]
+#[serde(tag = "kind", rename_all = "lowercase")]
+pub enum MountKind {
+    /// The account's primary My Files mount.
+    MyFiles,
+    /// A folder owned by this machine's Proton Drive device.
+    Device { sync_folder_id: i64 },
+    /// A future standalone mount rooted at a node shared with this account.
+    Shared { share_root_uid: String },
+}
+
+/// One local Proton Drive location as exposed over the control protocol.
+#[derive(Serialize, Deserialize, Debug, Clone)]
+pub struct MountSpec {
+    /// Presentation-row id. Device actions use the `sync_folder_id` carried by
+    /// [`MountKind::Device`], not this id.
+    pub id: i64,
+    pub kind: MountKind,
+    pub local_path: String,
+    pub root_uid: String,
+    pub root_share_id: String,
+    pub mode: MountMode,
+    pub access: MountAccess,
+    /// `idle` | `syncing` | `error` | `conflict` for device locations.
+    pub state: String,
+    /// Last successful device sync, epoch seconds; `0` when not applicable.
+    pub last_sync: i64,
+    /// A device mode switch accepted but not yet applied.
+    #[serde(default)]
+    pub pending_mode: Option<MountMode>,
+    /// Whether a FUSE session currently owns `local_path`.
+    #[serde(default)]
+    pub mounted: bool,
+    /// Live device sync progress, absent when no pass is running.
+    #[serde(default)]
+    pub progress: Option<SyncProgress>,
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn mount_mode_keeps_legacy_wire_strings() {
+        assert_eq!(
+            serde_json::to_string(&MountMode::Mirror).unwrap(),
+            r#""mirror""#
+        );
+        assert_eq!(
+            serde_json::to_string(&MountMode::OnDemand).unwrap(),
+            r#""ondemand""#
+        );
+        assert_eq!(
+            serde_json::from_str::<MountMode>(r#""mirror""#).unwrap(),
+            MountMode::Mirror
+        );
+        assert_eq!(
+            serde_json::from_str::<MountMode>(r#""ondemand""#).unwrap(),
+            MountMode::OnDemand
+        );
+    }
+
+    #[test]
+    fn mount_mode_tolerates_unknown_values() {
+        assert_eq!(
+            serde_json::from_str::<MountMode>(r#""from-the-future""#).unwrap(),
+            MountMode::Unknown
+        );
+    }
+}

crates/pdfs-core/src/profile.rs

@@ -17,6 +17,8 @@
 
 use serde::{Deserialize, Serialize};
 
+use crate::mounts::MountMode;
+
 /// File name of the profile inside the device root folder.
 pub const PROFILE_FILE_NAME: &str = "profile.json";
 
@@ -39,8 +41,9 @@ pub struct ProfileFolder {
     /// Absolute local path it was synced to. A *suggestion* on restore: another
     /// machine may have a different username, home, or mount layout.
     pub local_path: String,
-    /// `mirror` or `ondemand`.
-    pub mode: String,
+    /// `mirror` or `ondemand`. Unknown values written by a newer client do not
+    /// invalidate the rest of the profile.
+    pub mode: MountMode,
 }
 
 /// One pinned node (P5 pins), as `pins` stores it.
@@ -114,7 +117,7 @@ mod tests {
             folders: vec![ProfileFolder {
                 remote_uid: "vol~link".to_string(),
                 local_path: "/home/nils/Documents".to_string(),
-                mode: "mirror".to_string(),
+                mode: MountMode::Mirror,
             }],
             pins: vec![ProfilePin {
                 uid: "vol~pin".to_string(),
@@ -133,6 +136,52 @@ mod tests {
         assert_eq!(Profile::parse(&p.to_bytes().unwrap()).unwrap(), p);
     }
 
+    #[test]
+    fn profile_keeps_legacy_mode_bytes_and_parses_old_documents() {
+        let bytes = sample().to_bytes().unwrap();
+        let json = String::from_utf8(bytes).unwrap();
+        assert!(json.contains(r#""mode": "mirror""#));
+
+        let old = br#"{
+            "version": 1,
+            "device_uid": "dev-1",
+            "hostname": "old-client",
+            "saved_at": 1,
+            "folders": [
+                {
+                    "remote_uid": "vol~mirror",
+                    "local_path": "/home/me/Mirror",
+                    "mode": "mirror"
+                },
+                {
+                    "remote_uid": "vol~ondemand",
+                    "local_path": "/home/me/Cloud",
+                    "mode": "ondemand"
+                }
+            ]
+        }"#;
+        let profile = Profile::parse(old).unwrap();
+        assert_eq!(profile.folders[0].mode, MountMode::Mirror);
+        assert_eq!(profile.folders[1].mode, MountMode::OnDemand);
+    }
+
+    #[test]
+    fn unknown_folder_mode_does_not_reject_profile() {
+        let json = br#"{
+            "version": 1,
+            "device_uid": "dev-1",
+            "hostname": "future-client",
+            "saved_at": 1,
+            "folders": [{
+                "remote_uid": "vol~future",
+                "local_path": "/home/me/Future",
+                "mode": "streaming"
+            }]
+        }"#;
+        let profile = Profile::parse(json).unwrap();
+        assert_eq!(profile.folders[0].mode, MountMode::Unknown);
+    }
+
     /// A field added by a later client must not break this one's restore: the
     /// common subset is still usable, which is the whole reason `version` is
     /// reserved for breaking changes only.

crates/pdfs-fuse/src/background.rs

@@ -27,6 +27,83 @@ fn forget_and_notify(st: &mut State, notifier: Option<&Notifier>, uid: &NodeUid)
     true
 }
 
+fn invalidate_access_changes(notifier: Option<&Notifier>, changed: &[u64]) {
+    let Some(notifier) = notifier else {
+        return;
+    };
+    for &ino in changed {
+        let _ = notifier.inval_inode(INodeNo(ino), 0, 0);
+    }
+}
+
+fn hide_foreign_deleted_and_notify(st: &mut State, notifier: Option<&Notifier>, uid: &NodeUid) {
+    let child = st.by_uid.get(uid).copied();
+    let dentry = child.and_then(|ino| {
+        st.entries
+            .get(&ino)
+            .map(|entry| (entry.parent, entry.node.name.clone()))
+    });
+    let changed = st.downgrade_shared_subtree(uid);
+    st.hide_foreign_subtree(uid);
+    invalidate_access_changes(notifier, &changed);
+    if let (Some(notifier), Some((parent, name)), Some(child)) = (notifier, dentry, child) {
+        let _ = notifier.delete(INodeNo(parent), INodeNo(child), OsStr::new(&name));
+    }
+}
+
+/// Persist the fail-closed part of an access event and install the same denial
+/// in resident state even when SQLite rejects the write. The caller must not
+/// acknowledge the event when this returns an error.
+fn apply_access_downgrade(
+    db: &Db,
+    event: &DriveEvent,
+    mut deny: impl FnMut(Option<&NodeUid>),
+) -> pdfs_core::Result<()> {
+    match event {
+        DriveEvent::NodeDeleted { node_uid, .. } => {
+            let result = db.set_share_access(node_uid, Access::Viewer);
+            deny(Some(node_uid));
+            result
+        }
+        DriveEvent::ContinuityLost { .. }
+        | DriveEvent::ScopeAccessLost { .. }
+        | DriveEvent::SharedWithMeUpdated { .. } => {
+            let result = db.downgrade_all_share_access().map(|_| ());
+            deny(None);
+            result
+        }
+        _ => Ok(()),
+    }
+}
+
+fn apply_foreign_delete(
+    db: &Db,
+    uid: &NodeUid,
+    mut deny_and_hide: impl FnMut(&NodeUid),
+) -> pdfs_core::Result<()> {
+    let result = db.tombstone_foreign_subtree(uid);
+    deny_and_hide(uid);
+    result
+}
+
+fn is_foreign_node_delete(event: &DriveEvent, own_volume: &VolumeId) -> bool {
+    match event {
+        DriveEvent::NodeDeleted { node_uid, .. } => {
+            !is_own_or_virtual_uid(node_uid, own_volume) && !is_local_uid(node_uid)
+        }
+        _ => false,
+    }
+}
+
+fn event_serializes_shared_publication(event: &DriveEvent, own_volume: &VolumeId) -> bool {
+    matches!(
+        event,
+        DriveEvent::ContinuityLost { .. }
+            | DriveEvent::ScopeAccessLost { .. }
+            | DriveEvent::SharedWithMeUpdated { .. }
+    ) || is_foreign_node_delete(event, own_volume)
+}
+
 /// Apply one remote event to the local cache and notify the kernel so it drops
 /// any stale cached metadata/data for the affected inodes.
 ///
@@ -43,7 +120,33 @@ fn forget_and_notify(st: &mut State, notifier: Option<&Notifier>, uid: &NodeUid)
 /// read-side twin of `docs/BUGS.md` B74. Inode numbers are per-mount, so each
 /// mount must be notified through its **own** channel; that pairing is what
 /// [`Core::for_each_mount`] exists to preserve.
-fn apply_event(core: &Core, event: &DriveEvent, dirty: &mut DirtyParents) {
+fn apply_event(core: &Core, event: &DriveEvent, dirty: &mut DirtyParents) -> pdfs_core::Result<()> {
+    let foreign_delete = is_foreign_node_delete(event, &core.primary_root_uid.volume_id);
+    let serializes_shared_publication =
+        event_serializes_shared_publication(event, &core.primary_root_uid.volume_id);
+    let _publication = serializes_shared_publication.then(|| core.shared_publication.lock());
+    if serializes_shared_publication {
+        core.invalidate_shared_refreshes();
+    }
+    let mut apply_result = if let DriveEvent::NodeDeleted { node_uid, .. } = event
+        && foreign_delete
+    {
+        apply_foreign_delete(&core.db, node_uid, |uid| {
+            core.for_each_mount(|st, notifier| {
+                hide_foreign_deleted_and_notify(st, notifier, uid);
+            });
+        })
+    } else {
+        apply_access_downgrade(&core.db, event, |root| {
+            core.for_each_mount(|st, notifier| {
+                let changed = match root {
+                    Some(uid) => st.downgrade_shared_subtree(uid),
+                    None => st.downgrade_known_shared_access(),
+                };
+                invalidate_access_changes(notifier, &changed);
+            });
+        })
+    };
     match event {
         DriveEvent::NodeUpdated {
             node_uid,
@@ -105,15 +208,21 @@ fn apply_event(core: &Core, event: &DriveEvent, dirty: &mut DirtyParents) {
         }
         DriveEvent::NodeDeleted { node_uid, .. } => {
             core.cache.evict(node_uid);
-            core.for_each_mount(|st, notifier| {
-                forget_and_notify(st, notifier, node_uid);
-            });
+            if !foreign_delete {
+                core.for_each_mount(|st, notifier| {
+                    forget_and_notify(st, notifier, node_uid);
+                });
+            }
         }
-        // Continuity or scope was lost: our cached listings may be arbitrarily
-        // stale, so drop every listing and tell the kernel to forget all
-        // metadata. Inodes stay stable; dirs simply re-enumerate on next access.
-        DriveEvent::ContinuityLost { .. } | DriveEvent::ScopeAccessLost { .. } => {
-            warn!("event continuity lost; dropping all cached listings, resyncing lazily");
+        // Losing event continuity or any shared-access signal makes persisted
+        // shared roots untrustworthy. Keep owned/device trees unchanged, but
+        // fail every known shared subtree closed until a root refresh carries a
+        // current membership role.
+        DriveEvent::ContinuityLost { .. }
+        | DriveEvent::ScopeAccessLost { .. }
+        | DriveEvent::SharedWithMeUpdated { .. } => {
+            warn!("event access continuity lost; downgrading shared trees and resyncing lazily");
+            apply_result = apply_result.and(core.db.clear_state(SHARED_WITH_ME_SYNCED_MS));
             core.for_each_mount(|st, notifier| {
                 let dirs: Vec<u64> = st.children.keys().copied().collect();
                 for &ino in &dirs {
@@ -126,8 +235,20 @@ fn apply_event(core: &Core, event: &DriveEvent, dirty: &mut DirtyParents) {
         }
         // No substantive local change; the cursor advance is handled by the
         // caller persisting the event id.
-        DriveEvent::CursorAdvanced { .. } | DriveEvent::SharedWithMeUpdated { .. } => {}
+        DriveEvent::CursorAdvanced { .. } => {}
     }
+    apply_result
+}
+
+fn acknowledge_applied_event(
+    db: &Db,
+    event: &DriveEvent,
+    applied: pdfs_core::Result<()>,
+) -> pdfs_core::Result<DriveEventId> {
+    applied?;
+    let id = event.id().clone();
+    db.set_event_cursor(id.as_str())?;
+    Ok(id)
 }
 
 /// The folders one batch of events changed, collected so the listings are
@@ -296,12 +417,17 @@ pub(super) async fn run_event_sync(
                 warn!(error = %e, "sdk cache invalidation for event failed; retaining cursor for retry");
                 break;
             }
-            apply_event(&core, event, &mut dirty);
-            let applied = event.id().clone();
-            if let Err(e) = db.set_event_cursor(applied.as_str()) {
-                warn!(error = %e, "persist event cursor failed; retaining prior cursor for retry");
-                break;
-            }
+            let applied = match acknowledge_applied_event(
+                &db,
+                event,
+                apply_event(&core, event, &mut dirty),
+            ) {
+                Ok(applied) => applied,
+                Err(e) => {
+                    warn!(error = %e, "event application or acknowledgment failed; retaining prior cursor for retry");
+                    break;
+                }
+            };
             // Advance only after this exact event is durably acknowledged. If a
             // later event fails, polling resumes from here and replays nothing
             // that was not already made visible locally.
@@ -396,3 +522,274 @@ fn scan_local_once(
     }
     indexing.store(false, Ordering::Relaxed);
 }
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use std::cell::Cell;
+
+    fn uid(link: &str) -> NodeUid {
+        NodeUid::new(VolumeId::from("vol"), LinkId::from(link))
+    }
+
+    fn folder(volume: &str, link: &str, parent: Option<NodeUid>, name: &str) -> Node {
+        Node {
+            uid: NodeUid::new(VolumeId::from(volume), LinkId::from(link)),
+            parent_uid: parent,
+            kind: NodeKind::Folder,
+            name: name.to_string(),
+            creation_time: 1,
+            modification_time: 1,
+            trashed: false,
+            is_shared: false,
+            is_shared_publicly: false,
+            signature_email: None,
+            membership: None,
+            verification: Default::default(),
+        }
+    }
+
+    #[test]
+    fn foreign_delete_invalidates_an_earlier_refresh_generation() {
+        let own_volume = VolumeId::from("own");
+        let event = DriveEvent::NodeDeleted {
+            id: DriveEventId::from("foreign-delete"),
+            node_uid: NodeUid::new(VolumeId::from("foreign"), LinkId::from("child")),
+            parent_node_uid: None,
+        };
+        let generation = AtomicU64::new(7);
+        let captured = generation.load(Ordering::SeqCst);
+
+        assert!(event_serializes_shared_publication(&event, &own_volume));
+        generation.fetch_add(1, Ordering::SeqCst);
+
+        assert!(!refresh_generation_is_current(
+            captured,
+            generation.load(Ordering::SeqCst)
+        ));
+        let own_delete = DriveEvent::NodeDeleted {
+            id: DriveEventId::from("own-delete"),
+            node_uid: NodeUid::new(own_volume.clone(), LinkId::from("child")),
+            parent_node_uid: None,
+        };
+        assert!(!event_serializes_shared_publication(
+            &own_delete,
+            &own_volume
+        ));
+    }
+
+    #[test]
+    fn foreign_delete_tombstones_subtree_and_advances_cursor_after_success() {
+        let db = Db::open(std::path::Path::new(":memory:")).unwrap();
+        let root = folder("own", "root", None, "My Files");
+        let deleted = folder(
+            "foreign",
+            "deleted",
+            Some(root.uid.clone()),
+            "Deleted foreign",
+        );
+        let deep = folder(
+            "foreign",
+            "deep",
+            Some(deleted.uid.clone()),
+            "Searchable descendant",
+        );
+        db.upsert_nodes(&[root, deleted.clone(), deep.clone()])
+            .unwrap();
+        db.set_share_access(&deleted.uid, Access::Editor).unwrap();
+        db.enqueue_op(&PendingOp {
+            id: 0,
+            kind: OP_RENAME.to_string(),
+            uid: deep.uid.to_string(),
+            parent_uid: Some(deleted.uid.to_string()),
+            name: Some("pending".to_string()),
+            blob_path: None,
+            meta_json: Some("{}".to_string()),
+            created_at: 1,
+            attempts: 0,
+            last_error: None,
+            next_attempt_at: 0,
+        })
+        .unwrap();
+        let event = DriveEvent::NodeDeleted {
+            id: DriveEventId::from("foreign-delete-success"),
+            node_uid: deleted.uid.clone(),
+            parent_node_uid: deleted.parent_uid.clone(),
+        };
+        let denied = Cell::new(false);
+
+        let applied = apply_foreign_delete(&db, &deleted.uid, |_| denied.set(true));
+        let acknowledged = acknowledge_applied_event(&db, &event, applied).unwrap();
+
+        assert!(denied.get());
+        assert_eq!(acknowledged.as_str(), "foreign-delete-success");
+        assert_eq!(
+            db.get_event_cursor().unwrap().as_deref(),
+            Some("foreign-delete-success")
+        );
+        for uid in [&deleted.uid, &deep.uid] {
+            assert!(db.node_by_uid(&uid.to_string()).unwrap().unwrap().trashed);
+        }
+        assert!(db.search("Searchable", 10).unwrap().is_empty());
+        assert_eq!(db.pending_ops().unwrap().len(), 1);
+        assert_eq!(db.share_access(&deleted.uid).unwrap(), Some(Access::Viewer));
+    }
+
+    #[test]
+    fn foreign_delete_db_failure_denies_memory_and_retains_prior_cursor() {
+        let db = Db::open(std::path::Path::new(":memory:")).unwrap();
+        let root = folder("own", "root", None, "My Files");
+        let deleted = folder(
+            "foreign",
+            "deleted",
+            Some(root.uid.clone()),
+            "Deleted foreign",
+        );
+        let deep = folder(
+            "foreign",
+            "deep",
+            Some(deleted.uid.clone()),
+            "Still searchable",
+        );
+        db.upsert_nodes(&[root, deleted.clone(), deep.clone()])
+            .unwrap();
+        db.set_share_access(&deleted.uid, Access::Editor).unwrap();
+        db.set_event_cursor("prior-event").unwrap();
+        db.with_conn(|conn| {
+            conn.execute_batch(
+                "CREATE TRIGGER reject_foreign_tombstone
+                 BEFORE UPDATE OF trashed ON nodes
+                 WHEN OLD.uid = 'foreign~deleted'
+                 BEGIN SELECT RAISE(ABORT, 'forced tombstone failure'); END;",
+            )?;
+            Ok(())
+        })
+        .unwrap();
+        let event = DriveEvent::NodeDeleted {
+            id: DriveEventId::from("foreign-delete-failed"),
+            node_uid: deleted.uid.clone(),
+            parent_node_uid: deleted.parent_uid.clone(),
+        };
+        let denied = Cell::new(false);
+
+        let applied = apply_foreign_delete(&db, &deleted.uid, |_| denied.set(true));
+
+        assert!(applied.is_err());
+        assert!(
+            denied.get(),
+            "resident state must fail closed on DB failure"
+        );
+        assert!(acknowledge_applied_event(&db, &event, applied).is_err());
+        assert_eq!(
+            db.get_event_cursor().unwrap().as_deref(),
+            Some("prior-event")
+        );
+        assert!(
+            !db.node_by_uid(&deleted.uid.to_string())
+                .unwrap()
+                .unwrap()
+                .trashed
+        );
+        assert_eq!(db.search("searchable", 10).unwrap().len(), 1);
+        assert_eq!(
+            db.share_access(&deleted.uid).unwrap(),
+            Some(Access::Editor),
+            "the failed atomic transaction must not partially publish"
+        );
+    }
+
+    #[test]
+    fn deleted_share_downgrade_failure_denies_memory_and_retains_cursor() {
+        let db = Db::open(std::path::Path::new(":memory:")).unwrap();
+        let root = uid("shared");
+        db.set_share_access(&root, Access::Editor).unwrap();
+        db.with_conn(|conn| {
+            conn.execute_batch(
+                "CREATE TRIGGER reject_share_update
+                 BEFORE UPDATE ON share_access
+                 BEGIN SELECT RAISE(FAIL, 'forced downgrade failure'); END;",
+            )?;
+            Ok(())
+        })
+        .unwrap();
+        let event = DriveEvent::NodeDeleted {
+            id: DriveEventId::from("event-1"),
+            node_uid: root,
+            parent_node_uid: None,
+        };
+        let denied = Cell::new(false);
+
+        let applied = apply_access_downgrade(&db, &event, |root| {
+            denied.set(root.is_some());
+        });
+        assert!(applied.is_err());
+        assert!(denied.get(), "resident state must fail closed immediately");
+        assert!(acknowledge_applied_event(&db, &event, applied).is_err());
+        assert!(
+            db.get_event_cursor().unwrap().is_none(),
+            "failed downgrade must leave the event unacknowledged"
+        );
+    }
+
+    #[test]
+    fn deleted_resident_root_without_share_row_is_denied_and_tombstoned() {
+        let db = Db::open(std::path::Path::new(":memory:")).unwrap();
+        let root = uid("resident-without-row");
+        assert!(db.share_access(&root).unwrap().is_none());
+        let resident = std::cell::RefCell::new(std::collections::HashMap::from([(
+            root.clone(),
+            Access::Editor,
+        )]));
+        let event = DriveEvent::NodeDeleted {
+            id: DriveEventId::from("event-missing-row"),
+            node_uid: root.clone(),
+            parent_node_uid: None,
+        };
+
+        let applied = apply_access_downgrade(&db, &event, |target| {
+            assert_eq!(target, Some(&root));
+            resident.borrow_mut().insert(root.clone(), Access::Viewer);
+        });
+        assert!(applied.is_ok());
+        assert_eq!(resident.borrow().get(&root), Some(&Access::Viewer));
+        assert_eq!(db.share_access(&root).unwrap(), Some(Access::Viewer));
+
+        let acknowledged = acknowledge_applied_event(&db, &event, applied).unwrap();
+        assert_eq!(acknowledged.as_str(), "event-missing-row");
+        assert_eq!(
+            db.get_event_cursor().unwrap().as_deref(),
+            Some("event-missing-row")
+        );
+    }
+
+    #[test]
+    fn continuity_downgrade_failure_denies_memory_and_retains_cursor() {
+        let db = Db::open(std::path::Path::new(":memory:")).unwrap();
+        let root = uid("shared");
+        db.set_share_access(&root, Access::Editor).unwrap();
+        db.with_conn(|conn| {
+            conn.execute_batch(
+                "CREATE TRIGGER reject_all_share_updates
+                 BEFORE UPDATE ON share_access
+                 BEGIN SELECT RAISE(FAIL, 'forced global downgrade failure'); END;",
+            )?;
+            Ok(())
+        })
+        .unwrap();
+        let event = DriveEvent::ContinuityLost {
+            id: DriveEventId::from("event-2"),
+        };
+        let denied_all = Cell::new(false);
+
+        let applied = apply_access_downgrade(&db, &event, |root| {
+            denied_all.set(root.is_none());
+        });
+        assert!(applied.is_err());
+        assert!(
+            denied_all.get(),
+            "all resident shared roots must fail closed immediately"
+        );
+        assert!(acknowledge_applied_event(&db, &event, applied).is_err());
+        assert!(db.get_event_cursor().unwrap().is_none());
+    }
+}

crates/pdfs-fuse/src/control.rs

@@ -561,6 +561,10 @@ fn handle_control_conn(core: &Core, username: &str, mountpoint: &Path, stream: U
             Ok(items) => CtlResponse::Devices { items },
             Err(e) => CtlResponse::error(e),
         },
+        Ok(CtlRequest::ListLocations) => match core.list_locations() {
+            Ok(items) => CtlResponse::Locations { items },
+            Err(e) => CtlResponse::error(e),
+        },
         Ok(CtlRequest::RenameDevice { uid, name }) => match core.rename_device(&uid, &name) {
             Ok(()) => CtlResponse::Ok {
                 message: format!("renamed device to {name}"),
@@ -692,6 +696,28 @@ fn handle_control_conn(core: &Core, username: &str, mountpoint: &Path, stream: U
             },
             Err(e) => CtlResponse::error(e),
         },
+        Ok(CtlRequest::ShareNodeByUid {
+            uid,
+            emails,
+            role,
+            message,
+        }) => match core.share_node_by_uid(&uid, &emails, &role, message.as_deref()) {
+            Ok((proton, external)) => {
+                core.log_activity(
+                    ActivityKind::Share,
+                    &uid,
+                    format!("{} recipient(s) as {role}", proton + external),
+                    true,
+                );
+                CtlResponse::Ok {
+                    message: format!("invited {proton} Proton and {external} external user(s)"),
+                }
+            }
+            Err(e) => {
+                core.log_activity(ActivityKind::Share, &uid, &e, false);
+                CtlResponse::error(e)
+            }
+        },
         Ok(CtlRequest::ListShare { path }) => match rel_to_mount(mountpoint, &path) {
             Ok(rel) => match core.list_share(&rel) {
                 Ok((entries, link)) => CtlResponse::Share { entries, link },
@@ -699,6 +725,10 @@ fn handle_control_conn(core: &Core, username: &str, mountpoint: &Path, stream: U
             },
             Err(e) => CtlResponse::error(e),
         },
+        Ok(CtlRequest::ListShareByUid { uid }) => match core.list_share_by_uid(&uid) {
+            Ok((entries, link)) => CtlResponse::Share { entries, link },
+            Err(e) => CtlResponse::error(e),
+        },
         Ok(CtlRequest::UpdateShareRole {
             path,
             id,
@@ -713,6 +743,17 @@ fn handle_control_conn(core: &Core, username: &str, mountpoint: &Path, stream: U
             },
             Err(e) => CtlResponse::error(e),
         },
+        Ok(CtlRequest::UpdateShareRoleByUid {
+            uid,
+            id,
+            kind,
+            role,
+        }) => match core.update_share_role_by_uid(&uid, &id, kind, &role) {
+            Ok(()) => CtlResponse::Ok {
+                message: format!("role updated to {role}"),
+            },
+            Err(e) => CtlResponse::error(e),
+        },
         Ok(CtlRequest::RemoveShareEntry { path, id, kind }) => {
             match rel_to_mount(mountpoint, &path) {
                 Ok(rel) => match core.remove_share_entry(&rel, &id, kind) {
@@ -727,6 +768,17 @@ fn handle_control_conn(core: &Core, username: &str, mountpoint: &Path, stream: U
                 Err(e) => CtlResponse::error(e),
             }
         }
+        Ok(CtlRequest::RemoveShareEntryByUid { uid, id, kind }) => {
+            match core.remove_share_entry_by_uid(&uid, &id, kind) {
+                Ok(()) => {
+                    core.log_activity(ActivityKind::Unshare, &uid, "access removed", true);
+                    CtlResponse::Ok {
+                        message: "removed".to_string(),
+                    }
+                }
+                Err(e) => CtlResponse::error(e),
+            }
+        }
         Ok(CtlRequest::CreatePublicLink {
             path,
             role,
@@ -745,6 +797,21 @@ fn handle_control_conn(core: &Core, username: &str, mountpoint: &Path, stream: U
             },
             Err(e) => CtlResponse::error(e),
         },
+        Ok(CtlRequest::CreatePublicLinkByUid {
+            uid,
+            role,
+            password,
+            expires,
+        }) => match core.create_public_link_by_uid(&uid, &role, password.as_deref(), expires) {
+            Ok(link) => {
+                core.log_activity(ActivityKind::PublicLink, &uid, "link created", true);
+                CtlResponse::PublicLink { link }
+            }
+            Err(e) => {
+                core.log_activity(ActivityKind::PublicLink, &uid, &e, false);
+                CtlResponse::error(e)
+            }
+        },
         Ok(CtlRequest::RemovePublicLink { path, id }) => match rel_to_mount(mountpoint, &path) {
             Ok(rel) => match core.remove_public_link(&rel, &id) {
                 Ok(()) => {
@@ -757,6 +824,17 @@ fn handle_control_conn(core: &Core, username: &str, mountpoint: &Path, stream: U
             },
             Err(e) => CtlResponse::error(e),
         },
+        Ok(CtlRequest::RemovePublicLinkByUid { uid, id }) => {
+            match core.remove_public_link_by_uid(&uid, &id) {
+                Ok(()) => {
+                    core.log_activity(ActivityKind::Unshare, &uid, "link removed", true);
+                    CtlResponse::Ok {
+                        message: "public link removed".to_string(),
+                    }
+                }
+                Err(e) => CtlResponse::error(e),
+            }
+        }
         Ok(CtlRequest::ListSharedWithMe) => match core.list_shared_with_me() {
             Ok(entries) => CtlResponse::Entries { entries },
             Err(e) => CtlResponse::error(e),

crates/pdfs-fuse/src/devices.rs

@@ -11,12 +11,13 @@ use std::collections::HashMap;
 use std::path::{Path, PathBuf};
 use std::sync::Arc;
 
-use fuser::{Config, MountOption, Session};
 use parking_lot::Mutex;
 use pdfs_core::control::{
-    ActivityKind, DeviceInfo, JobItem, SyncFolderInfo, SyncPhase, SyncProgress,
+    ActivityKind, DeviceInfo, JobItem, MountKind, MountSpec, SyncFolderInfo, SyncPhase,
+    SyncProgress,
 };
 use pdfs_core::db::{StoredDevice, StoredSyncFolder};
+use pdfs_core::mounts::MountMode;
 use pdfs_core::{CoreError, CoreResult};
 use proton_drive_rs::proton_sdk::ids::{DeviceUid, NodeUid};
 use proton_drive_rs::{DeviceType, Node};
@@ -25,11 +26,69 @@ use tracing::{info, warn};
 
 use super::sync::{self, base_name};
 use super::{
-    BackgroundSession, Core, ProtonFs, State, SwitchBlocked, clear_stale_mount, device_type_str,
-    dir_is_empty, evict_dir_contents, fuse_connection_id, is_stale_mount, now_secs, parse_uid,
-    sync_folder_info, this_hostname, umount_session_unblocked,
+    Core, SecondaryInsertRejection, SecondaryMount, State, SwitchBlocked, clear_stale_mount,
+    device_type_str, dir_is_empty, evict_dir_contents, fuse_connection_id, is_stale_mount,
+    now_secs, parse_uid, spawn_session, sync_folder_info, this_hostname,
 };
 
+/// A mode that this daemon is allowed to apply.
+///
+/// Persisted and control-protocol values first pass through [`MountMode`] so
+/// forward-compatible unknown values never reach either destructive transition.
+#[derive(Clone, Copy, Debug, PartialEq, Eq)]
+pub(crate) enum ApplicableMountMode {
+    Mirror,
+    OnDemand,
+}
+
+impl ApplicableMountMode {
+    fn parse(value: &str) -> Result<Self, String> {
+        match MountMode::from(value) {
+            MountMode::Mirror => Ok(Self::Mirror),
+            MountMode::OnDemand => Ok(Self::OnDemand),
+            MountMode::Unknown => Err(format!("unknown mode {value:?} (want mirror|ondemand)")),
+        }
+    }
+
+    const fn as_str(self) -> &'static str {
+        match self {
+            Self::Mirror => "mirror",
+            Self::OnDemand => "ondemand",
+        }
+    }
+}
+
+fn select_mode_transition(
+    current: &str,
+    target: &str,
+) -> Result<Option<ApplicableMountMode>, String> {
+    let current = ApplicableMountMode::parse(current)
+        .map_err(|error| format!("unsupported current mode: {error}"))?;
+    let target = ApplicableMountMode::parse(target)
+        .map_err(|error| format!("unsupported target mode: {error}"))?;
+    Ok((current != target).then_some(target))
+}
+
+fn restore_snapshot_matches(snapshot: &StoredSyncFolder, current: &StoredSyncFolder) -> bool {
+    current.id == snapshot.id
+        && current.local_path == snapshot.local_path
+        && current.remote_uid == snapshot.remote_uid
+        && current.remote_share_id == snapshot.remote_share_id
+        && current.mode == "ondemand"
+}
+
+fn pending_intent_matches(pending: Option<&str>, expected: Option<&str>) -> bool {
+    expected.is_none_or(|expected| pending == Some(expected))
+}
+
+fn commit_after_teardown<T, E>(
+    teardown: Result<(), E>,
+    commit: impl FnOnce() -> T,
+) -> Result<T, E> {
+    teardown?;
+    Ok(commit())
+}
+
 /// The device uid this machine has been adopted into, from `config.json`.
 ///
 /// Read fresh each time rather than cached on [`Core`]: adoption rewrites the
@@ -57,6 +116,22 @@ pub(crate) fn set_adopted_device_uid(uid: Option<&str>) -> CoreResult<()> {
 impl Core {
     // ---- devices ----------------------------------------------------------
 
+    /// Unified local-location listing for the control protocol.
+    pub(crate) fn list_locations(&self) -> CoreResult<Vec<MountSpec>> {
+        let progress = self.sync_progress.lock();
+        let mut locations = self
+            .db
+            .mount_list()
+            .map_err(|e| CoreError::internal(format!("db: {e:?}")))?;
+        for location in &mut locations {
+            location.mounted = self.states.is_mounted_at(Path::new(&location.local_path));
+            if let MountKind::Device { sync_folder_id } = &location.kind {
+                location.progress = progress.get(sync_folder_id).cloned();
+            }
+        }
+        Ok(locations)
+    }
+
     /// List the account's registered devices, flagging the one *this* machine
     /// syncs to so a front-end can treat it as more than another computer in the
     /// list — deleting it takes this machine's synced folders down with it.
@@ -439,6 +514,8 @@ impl Core {
     /// Remove a synced folder from the sync set. `delete_remote` also deletes its
     /// folder under the device root; otherwise the cloud copy is left in place.
     pub(crate) fn remove_sync_folder(&self, id: i64, delete_remote: bool) -> CoreResult<()> {
+        let lock = self.sync_lock(id);
+        let _guard = lock.lock();
         let folder = self
             .db
             .sync_folder_get(id)
@@ -449,19 +526,16 @@ impl Core {
         // folder the daemon no longer tracks, and nothing would ever unmount it.
         // Tear it down first — including before trashing the remote tree it
         // serves, which would otherwise leave it answering for deleted nodes.
-        if let Some((session, conn)) = self.mounts.lock().remove(&id) {
-            if let Err(e) = umount_session_unblocked(session, conn) {
-                warn!(id, error = %e, "unmount on-demand folder failed");
-            } else {
-                info!(id, path = %folder.local_path, "unmounted on-demand folder");
-            }
-        }
-        if delete_remote
-            && let Some(uid) = parse_uid(&folder.remote_uid)
-            && let Err(e) = self.rt.block_on(self.client.trash_nodes(&[uid]))
+        if let Some(mount) = self.mounts.lock().remove(&id)
+            && let Err(error) = commit_after_teardown(mount.teardown(), || ())
         {
-            warn!(id, error = %e, "delete remote device folder failed");
+            let _ = self.db.sync_folder_set_state(id, "error", now_secs());
+            return Err(CoreError::internal(format!(
+                "cannot remove synced folder: unmount {} failed: {error}",
+                folder.local_path
+            )));
         }
+        info!(id, path = %folder.local_path, "unmounted on-demand folder");
         if !self
             .db
             .sync_folder_remove(id)
@@ -469,8 +543,15 @@ impl Core {
         {
             return Err(CoreError::invalid(format!("no synced folder with id {id}")));
         }
+        drop(_guard);
         // Stop watching the folder we just dropped.
         let _ = self.sync_tx.send(sync::SyncMsg::Rewatch);
+        if delete_remote
+            && let Some(uid) = parse_uid(&folder.remote_uid)
+            && let Err(e) = self.rt.block_on(self.client.trash_nodes(&[uid]))
+        {
+            warn!(id, error = %e, "delete remote device folder failed");
+        }
         Ok(())
     }
 
@@ -489,6 +570,8 @@ impl Core {
     /// (devices.md Phase 3).
     pub(crate) fn fork_state(&self) -> Core {
         let mut fork = self.clone();
+        fork.primary = false;
+        let share_access = self.state.lock().share_access.clone();
         fork.state = Arc::new(Mutex::new(State {
             entries: HashMap::new(),
             by_uid: HashMap::new(),
@@ -497,19 +580,17 @@ impl Core {
             active_writes: HashMap::new(),
             handles: HashMap::new(),
             next_fh: 1,
+            access_changes: std::collections::HashSet::new(),
+            share_access,
             db: self.db.clone(),
         }));
         // A fresh inode space needs a fresh notification channel: this fork's
         // session is the only one that knows these inodes, so it must be the one
         // notified about them. Filled in by `spawn_ondemand_mount`.
         fork.notifier = Arc::new(OnceLock::new());
+        fork.session_live = Arc::new(std::sync::atomic::AtomicBool::new(false));
         // Size upgrades are keyed by inode, which is per-fork too.
         fork.size_upgrades = Arc::new(Mutex::new(HashMap::new()));
-        // The daemon's single drain thread belongs to the primary mount, but it
-        // drains ops for nodes that live *here*. Publishing this inode space is
-        // what lets it find them; without it a queued create's node keeps its
-        // `local~` uid after the upload lands and reads it as empty (B74).
-        fork.register_state();
         fork
     }
 
@@ -525,49 +606,84 @@ impl Core {
     /// running — which, seeing a queued `ondemand`, also stops pulling down files
     /// it is about to evict ([`Core::push_pass`]).
     pub(crate) fn request_sync_folder_mode(&self, id: i64, mode: &str) -> CoreResult<String> {
-        if mode != "mirror" && mode != "ondemand" {
-            return Err(CoreError::invalid(format!(
-                "unknown mode {mode:?} (want mirror|ondemand)"
-            )));
-        }
+        // Preserve the existing control behavior: reject an unsupported request
+        // before looking up the folder, then validate the persisted source too.
+        let target_mode = ApplicableMountMode::parse(mode).map_err(CoreError::invalid)?;
         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 == mode {
-            // Already there. A queued switch the other way is the user changing
-            // their mind back before it landed, so withdraw it.
-            if folder.pending_mode.is_some() {
-                self.db
-                    .sync_folder_set_pending_mode(id, None)
-                    .map_err(|e| CoreError::internal(format!("db: {e:?}")))?;
-                let _ = self.sync_tx.send(sync::SyncMsg::Rewatch);
-                return Ok(format!("staying {mode}"));
+        let current_mode = ApplicableMountMode::parse(&folder.mode)
+            .map_err(|error| CoreError::invalid(format!("unsupported current mode: {error}")))?;
+        if current_mode == target_mode {
+            let mode_str = target_mode.as_str();
+            let lock = self.sync_lock(id);
+            match lock.try_lock() {
+                Some(_guard) => {
+                    let current = 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}"))
+                        })?;
+                    let locked_mode =
+                        ApplicableMountMode::parse(&current.mode).map_err(|error| {
+                            CoreError::invalid(format!("unsupported current mode: {error}"))
+                        })?;
+                    if locked_mode == target_mode {
+                        self.db
+                            .sync_folder_set_pending_mode(id, None)
+                            .map_err(|e| CoreError::internal(format!("db: {e:?}")))?;
+                        let _ = self.sync_tx.send(sync::SyncMsg::Rewatch);
+                        return Ok(if current.pending_mode.is_some() {
+                            format!("staying {mode_str}")
+                        } else {
+                            format!("already {mode_str}")
+                        });
+                    }
+                }
+                None => {
+                    // A transition or reconcile owns the folder lock. Record
+                    // this request instead of clearing the old target: if a
+                    // queued switch already passed its recheck, its mode write
+                    // preserves this opposite marker and the engine switches
+                    // back next.
+                    self.db
+                        .sync_folder_set_pending_mode(id, Some(mode_str))
+                        .map_err(|e| CoreError::internal(format!("db: {e:?}")))?;
+                    let _ = self.sync_tx.send(sync::SyncMsg::Reconcile(id));
+                    return Ok(format!("staying {mode_str}"));
+                }
             }
-            return Ok(format!("already {mode}"));
         }
+        let mode = target_mode;
+        let mode_str = target_mode.as_str();
 
-        match self.apply_sync_folder_mode(id, mode) {
+        match self.apply_sync_folder_mode(id, mode, None) {
             Ok(message) => Ok(message),
             // Not switchable this instant — remember the intent instead of making
             // the user retry, and kick a pass to clear whatever is in the way.
             Err(SwitchBlocked::NotNow) => {
                 self.db
-                    .sync_folder_set_pending_mode(id, Some(mode))
+                    .sync_folder_set_pending_mode(id, Some(mode_str))
                     .map_err(|e| CoreError::internal(format!("db: {e:?}")))?;
                 let _ = self.sync_tx.send(sync::SyncMsg::Reconcile(id));
                 Ok(match mode {
-                    "ondemand" => format!(
+                    ApplicableMountMode::OnDemand => format!(
                         "{} will go on-demand once its local changes are uploaded",
                         base_name(&folder.local_path)
                     ),
-                    _ => format!(
+                    ApplicableMountMode::Mirror => format!(
                         "{} will start mirroring once the current sync finishes",
                         base_name(&folder.local_path)
                     ),
                 })
             }
+            Err(SwitchBlocked::Superseded) => Err(CoreError::internal(
+                "direct mode request was unexpectedly superseded",
+            )),
             Err(SwitchBlocked::Failed(e)) => Err(CoreError::internal(e)),
         }
     }
@@ -581,27 +697,45 @@ impl Core {
         let Ok(Some(folder)) = self.db.sync_folder_get(id) else {
             return;
         };
-        let Some(mode) = folder.pending_mode.as_deref() else {
+        let Some(expected_mode) = folder.pending_mode.as_deref() else {
             return;
         };
-        if folder.mode == mode {
-            let _ = self.db.sync_folder_set_pending_mode(id, None);
-            return;
-        }
-        match self.apply_sync_folder_mode(id, mode) {
+        let mode = match select_mode_transition(&folder.mode, expected_mode) {
+            Ok(Some(mode)) => mode,
+            Ok(None) => {
+                let _ = self.db.sync_folder_clear_pending_mode_if(id, expected_mode);
+                return;
+            }
+            Err(error) => {
+                warn!(
+                    id,
+                    current_mode = %folder.mode,
+                    pending_mode = %expected_mode,
+                    %error,
+                    "withdrawing unsafe queued mode transition"
+                );
+                let _ = self.db.sync_folder_clear_pending_mode_if(id, expected_mode);
+                return;
+            }
+        };
+        let mode_str = mode.as_str();
+        match self.apply_sync_folder_mode(id, mode, Some(expected_mode)) {
             Ok(message) => {
-                info!(id, mode, "applied queued mode switch");
+                info!(id, mode = mode_str, "applied queued mode switch");
                 self.log_activity(ActivityKind::Sync, &message, "", true);
             }
             // Still blocked: the pass could not get everything up, so the local copy
             // is not safe to evict yet. Leave the request standing — the next pass
             // (poll, or the retry the engine schedules) tries again.
             Err(SwitchBlocked::NotNow) => {
-                info!(id, mode, "queued mode switch still waiting");
+                info!(id, mode = mode_str, "queued mode switch still waiting");
+            }
+            Err(SwitchBlocked::Superseded) => {
+                info!(id, mode = mode_str, "queued mode switch was replaced");
             }
             Err(SwitchBlocked::Failed(e)) => {
-                warn!(id, mode, error = %e, "queued mode switch failed; withdrawing");
-                let _ = self.db.sync_folder_set_pending_mode(id, None);
+                warn!(id, mode = mode_str, error = %e, "queued mode switch failed; withdrawing");
+                let _ = self.db.sync_folder_clear_pending_mode_if(id, expected_mode);
                 self.log_activity(
                     ActivityKind::Sync,
                     format!("couldn't switch {}", base_name(&folder.local_path)),
@@ -627,8 +761,10 @@ impl Core {
     pub(crate) fn apply_sync_folder_mode(
         &self,
         id: i64,
-        mode: &str,
+        mode: ApplicableMountMode,
+        expected_pending: Option<&str>,
     ) -> Result<String, SwitchBlocked> {
+        let mode_str = mode.as_str();
         // Hold the folder's lock for the whole switch so no reconcile pass can be
         // running over the tree we are about to evict (or start while we mount over
         // it). A pass in flight holds the lock for its full duration, so `try_lock`
@@ -646,13 +782,18 @@ impl Core {
             .sync_folder_get(id)
             .map_err(|e| SwitchBlocked::Failed(format!("db: {e:?}")))?
             .ok_or_else(|| SwitchBlocked::Failed(format!("no synced folder with id {id}")))?;
-        if folder.mode == mode {
-            return Ok(format!("already {mode}"));
+        if !pending_intent_matches(folder.pending_mode.as_deref(), expected_pending) {
+            return Err(SwitchBlocked::Superseded);
+        }
+        let current_mode = ApplicableMountMode::parse(&folder.mode)
+            .map_err(|e| SwitchBlocked::Failed(format!("unsupported current mode: {e}")))?;
+        if current_mode == mode {
+            return Ok(format!("already {mode_str}"));
         }
         let local = PathBuf::from(&folder.local_path);
 
         match mode {
-            "ondemand" => {
+            ApplicableMountMode::OnDemand => {
                 // Only flip a folder that is fully in sync — a failed reconcile means
                 // local edits could still be un-uploaded, and we are about to delete
                 // the local copy. Not an error: a pass makes this true, and the queued
@@ -699,25 +840,28 @@ impl Core {
                 if let Err(e) = evict_dir_contents(&local) {
                     warn!(id, path = %local.display(), error = %e, "evict local dir contents failed");
                 }
-                let session = self.spawn_ondemand_mount(&local, root).map_err(|e| {
+                let mount = self.spawn_ondemand_mount(&local, root).map_err(|e| {
                     SwitchBlocked::Failed(format!(
                         "mount ondemand failed after local cache eviction; switch back to mirror to restore it: {e}"
                     ))
                 })?;
-                self.mounts
-                    .lock()
-                    .insert(id, (session, fuse_connection_id(&local)));
+                self.publish_secondary_mount(id, mount)
+                    .map_err(SwitchBlocked::Failed)?;
                 let _ = self.sync_tx.send(sync::SyncMsg::Rewatch);
                 self.db.sync_folder_set_state(id, "idle", now_secs()).ok();
                 info!(id, path = %local.display(), "mounted sync folder on-demand");
                 Ok(format!("{} is now on-demand", local.display()))
             }
-            _ => {
+            ApplicableMountMode::Mirror => {
                 // ondemand→mirror: tear down the secondary mount first.
-                if let Some((session, conn)) = self.mounts.lock().remove(&id)
-                    && let Err(e) = umount_session_unblocked(session, conn)
+                if let Some(mount) = self.mounts.lock().remove(&id)
+                    && let Err(error) = commit_after_teardown(mount.teardown(), || ())
                 {
-                    warn!(id, error = %e, "unmount on-demand folder failed");
+                    let _ = self.db.sync_folder_set_state(id, "error", now_secs());
+                    return Err(SwitchBlocked::Failed(format!(
+                        "unmount {} failed; folder remains on-demand: {error}",
+                        local.display()
+                    )));
                 }
                 // The evicted local tree makes the old baseline lie ("everything
                 // deleted locally"); clear it so the reconcile is a pure download.
@@ -745,23 +889,52 @@ impl Core {
         &self,
         local: &Path,
         root: Node,
-    ) -> CoreResult<BackgroundSession> {
-        clear_stale_mount(local);
-        let mut config = Config::default();
-        config.mount_options = vec![
-            MountOption::FSName("protondrive".to_string()),
-            MountOption::Subtype("protondrive".to_string()),
-            MountOption::DefaultPermissions,
-        ];
+    ) -> CoreResult<SecondaryMount> {
         let core = self.fork_state();
-        let fs = ProtonFs::new(core.clone(), root);
-        let session = Session::new(fs, local, &config)
-            .and_then(|s| s.spawn())
+        let session_live = core.session_live.clone();
+        // The fork owns this state/path registration. `spawn_session` only
+        // marks it live after FUSE has spawned successfully.
+        core.register_state(local);
+        let session = spawn_session(&core, local, root)
             .map_err(|e| CoreError::internal(format!("mount {}: {e}", local.display())))?;
-        // Hand this fork its own session's notification channel, so a background
-        // size upgrade can drop the kernel's cached attrs for these inodes.
-        let _ = core.notifier.set(session.notifier());
-        Ok(session)
+        Ok(SecondaryMount::new(
+            session,
+            fuse_connection_id(local),
+            session_live,
+        ))
+    }
+
+    /// Publish one newly spawned secondary or explicitly tear it down when
+    /// shutdown has closed publication or another session already owns the id.
+    fn publish_secondary_mount(&self, id: i64, mount: SecondaryMount) -> Result<(), String> {
+        let rejected = self.mounts.lock().insert(id, mount);
+        let Err((reason, mount)) = rejected else {
+            return Ok(());
+        };
+        let reason = match reason {
+            SecondaryInsertRejection::Closed => "daemon is shutting down",
+            SecondaryInsertRejection::Duplicate => "folder already has a live mount",
+        };
+        match mount.teardown() {
+            Ok(()) => Err(reason.to_string()),
+            Err(error) => Err(format!("{reason}; rejected mount teardown failed: {error}")),
+        }
+    }
+
+    fn mark_restore_error_if_current(&self, snapshot: &StoredSyncFolder) {
+        let lock = self.sync_lock(snapshot.id);
+        let _guard = lock.lock();
+        if self
+            .db
+            .sync_folder_get(snapshot.id)
+            .ok()
+            .flatten()
+            .is_some_and(|current| restore_snapshot_matches(snapshot, &current))
+        {
+            let _ = self
+                .db
+                .sync_folder_set_state(snapshot.id, "error", now_secs());
+        }
     }
 
     /// Re-establish FUSE mounts for folders left in `ondemand` mode across a daemon
@@ -782,14 +955,57 @@ impl Core {
             if folder.mode != "ondemand" {
                 continue;
             }
-            let local = PathBuf::from(&folder.local_path);
-            // A daemon killed before it could unmount (systemd's stop timeout,
-            // say) leaves this path attached to a dead FUSE connection: it still
-            // exists, but every stat on it fails with ENOTCONN — so `is_dir()`
-            // reads it as *missing* and the folder gets parked in `error` on
-            // every subsequent start, with no way back but a manual
-            // `fusermount -u`. Detach the corpse first; the directory
-            // underneath then restores normally.
+            let Some(root_uid) = parse_uid(&folder.remote_uid) else {
+                warn!(id = folder.id, "restore on-demand: bad remote uid");
+                self.mark_restore_error_if_current(&folder);
+                continue;
+            };
+            let root = match self
+                .rt
+                .block_on(self.client.enumerate_nodes(std::slice::from_ref(&root_uid)))
+            {
+                Ok(v) => match v.into_iter().next() {
+                    Some(n) => n,
+                    None => {
+                        warn!(id = folder.id, "restore on-demand: remote folder gone");
+                        self.mark_restore_error_if_current(&folder);
+                        continue;
+                    }
+                },
+                Err(e) => {
+                    warn!(id = folder.id, error = %e, "restore on-demand: fetch remote failed");
+                    self.mark_restore_error_if_current(&folder);
+                    continue;
+                }
+            };
+            let lock = self.sync_lock(folder.id);
+            let _guard = lock.lock();
+            let current = match self.db.sync_folder_get(folder.id) {
+                Ok(Some(current)) if restore_snapshot_matches(&folder, &current) => current,
+                Ok(_) => {
+                    info!(
+                        id = folder.id,
+                        "restore on-demand: folder changed while fetching"
+                    );
+                    continue;
+                }
+                Err(error) => {
+                    warn!(
+                        id = folder.id,
+                        ?error,
+                        "restore on-demand: cannot re-read folder"
+                    );
+                    continue;
+                }
+            };
+            if !self.mounts.lock().is_accepting() {
+                info!(id = folder.id, "restore on-demand: shutdown in progress");
+                continue;
+            }
+            let local = PathBuf::from(&current.local_path);
+            // A daemon killed before it could unmount can leave a dead FUSE
+            // connection over the path. Clear it only after the row identity
+            // and mode have been revalidated under the folder lock.
             if is_stale_mount(&local) {
                 warn!(id = folder.id, path = %local.display(), "restore on-demand: clearing stale mount");
                 clear_stale_mount(&local);
@@ -801,11 +1017,6 @@ impl Core {
                     .sync_folder_set_state(folder.id, "error", now_secs());
                 continue;
             }
-            // An `ondemand` folder's local dir is empty by construction — the switch
-            // evicts it. Finding files there means the row is lying (a switch that
-            // died between persisting the mode and evicting), and mounting over them
-            // would hide real local data behind the remote tree. Leave the files
-            // alone and let the user resolve it.
             match dir_is_empty(&local) {
                 Ok(true) => {}
                 Ok(false) => {
@@ -827,40 +1038,16 @@ impl Core {
                     continue;
                 }
             }
-            let Some(root_uid) = parse_uid(&folder.remote_uid) else {
-                warn!(id = folder.id, "restore on-demand: bad remote uid");
-                continue;
-            };
-            let root = match self
-                .rt
-                .block_on(self.client.enumerate_nodes(std::slice::from_ref(&root_uid)))
-            {
-                Ok(v) => match v.into_iter().next() {
-                    Some(n) => n,
-                    None => {
-                        warn!(id = folder.id, "restore on-demand: remote folder gone");
-                        let _ = self
-                            .db
-                            .sync_folder_set_state(folder.id, "error", now_secs());
-                        continue;
+            match self.spawn_ondemand_mount(&local, root) {
+                Ok(mount) => match self.publish_secondary_mount(folder.id, mount) {
+                    Ok(()) => {
+                        let _ = self.db.sync_folder_set_state(folder.id, "idle", now_secs());
+                        info!(id = folder.id, path = %local.display(), "remounted on-demand folder");
+                    }
+                    Err(error) => {
+                        warn!(id = folder.id, %error, "restore on-demand: mount rejected");
                     }
                 },
-                Err(e) => {
-                    warn!(id = folder.id, error = %e, "restore on-demand: fetch remote failed");
-                    let _ = self
-                        .db
-                        .sync_folder_set_state(folder.id, "error", now_secs());
-                    continue;
-                }
-            };
-            match self.spawn_ondemand_mount(&local, root) {
-                Ok(session) => {
-                    self.mounts
-                        .lock()
-                        .insert(folder.id, (session, fuse_connection_id(&local)));
-                    let _ = self.db.sync_folder_set_state(folder.id, "idle", now_secs());
-                    info!(id = folder.id, path = %local.display(), "remounted on-demand folder");
-                }
                 Err(e) => {
                     warn!(id = folder.id, error = %e, "restore on-demand: mount failed");
                     let _ = self
@@ -871,3 +1058,118 @@ impl Core {
         }
     }
 }
+
+#[cfg(test)]
+mod tests {
+    use pdfs_core::db::StoredSyncFolder;
+
+    use super::{
+        ApplicableMountMode, commit_after_teardown, pending_intent_matches,
+        restore_snapshot_matches, select_mode_transition,
+    };
+
+    #[test]
+    fn unknown_mode_cannot_select_a_destructive_transition() {
+        let mut unmounts = 0;
+        let mut baseline_clears = 0;
+        let mut mode_writes = 0;
+        if let Ok(mode) = ApplicableMountMode::parse("streaming") {
+            match mode {
+                ApplicableMountMode::Mirror => {
+                    unmounts += 1;
+                    baseline_clears += 1;
+                    mode_writes += 1;
+                }
+                ApplicableMountMode::OnDemand => {
+                    mode_writes += 1;
+                }
+            }
+        }
+        assert_eq!((unmounts, baseline_clears, mode_writes), (0, 0, 0));
+        assert_eq!(
+            ApplicableMountMode::parse("streaming"),
+            Err("unknown mode \"streaming\" (want mirror|ondemand)".to_string())
+        );
+        assert_eq!(
+            ApplicableMountMode::parse("mirror"),
+            Ok(ApplicableMountMode::Mirror)
+        );
+        assert_eq!(
+            ApplicableMountMode::parse("ondemand"),
+            Ok(ApplicableMountMode::OnDemand)
+        );
+    }
+
+    #[test]
+    fn unknown_source_mode_with_pending_mirror_cannot_select_a_transition() {
+        let mut destructive_helper_reached = false;
+        let selected = select_mode_transition("streaming", "mirror");
+        if let Ok(Some(_)) = selected {
+            destructive_helper_reached = true;
+        }
+
+        assert!(!destructive_helper_reached);
+        assert_eq!(
+            selected,
+            Err(
+                "unsupported current mode: unknown mode \"streaming\" (want mirror|ondemand)"
+                    .to_string()
+            )
+        );
+    }
+
+    fn folder(local_path: &str, remote_uid: &str, mode: &str) -> StoredSyncFolder {
+        StoredSyncFolder {
+            id: 7,
+            local_path: local_path.to_string(),
+            remote_uid: remote_uid.to_string(),
+            remote_share_id: "share".to_string(),
+            mode: mode.to_string(),
+            pending_mode: None,
+            state: "idle".to_string(),
+            last_sync: 0,
+        }
+    }
+
+    #[test]
+    fn stale_restore_identity_or_mode_is_rejected() {
+        let snapshot = folder("/mnt/folder", "volume~node", "ondemand");
+        assert!(restore_snapshot_matches(
+            &snapshot,
+            &folder("/mnt/folder", "volume~node", "ondemand")
+        ));
+        assert!(!restore_snapshot_matches(
+            &snapshot,
+            &folder("/mnt/replaced", "volume~node", "ondemand")
+        ));
+        assert!(!restore_snapshot_matches(
+            &snapshot,
+            &folder("/mnt/folder", "volume~other", "ondemand")
+        ));
+        assert!(!restore_snapshot_matches(
+            &snapshot,
+            &folder("/mnt/folder", "volume~node", "mirror")
+        ));
+    }
+
+    #[test]
+    fn teardown_failure_prevents_follow_up_state_changes() {
+        let mut commits = 0;
+        let result = commit_after_teardown::<_, &str>(Err("busy"), || {
+            commits += 1;
+        });
+        assert_eq!(result, Err("busy"));
+        assert_eq!(commits, 0);
+
+        commit_after_teardown::<_, &str>(Ok(()), || commits += 1).unwrap();
+        assert_eq!(commits, 1);
+    }
+
+    #[test]
+    fn canceled_or_replaced_queued_intent_cannot_transition() {
+        assert!(pending_intent_matches(Some("ondemand"), Some("ondemand")));
+        assert!(!pending_intent_matches(None, Some("ondemand")));
+        assert!(!pending_intent_matches(Some("mirror"), Some("ondemand")));
+        assert!(pending_intent_matches(Some("mirror"), None));
+    }
+}

crates/pdfs-fuse/src/drain.rs

@@ -27,7 +27,7 @@ use std::time::Duration;
 
 use pdfs_core::cache::{Baseline, StagedWrite};
 use pdfs_core::control::{ActivityKind, TransferDirection};
-use pdfs_core::db::{OP_CREATE, OP_MKDIR, OP_RENAME, OP_REVISION, OP_TRASH, PendingOp};
+use pdfs_core::db::{OP_CREATE, OP_MKDIR, OP_RENAME, OP_REVISION, OP_TRASH, PendingOp, RenameMeta};
 use proton_drive_rs::Node;
 use proton_drive_rs::proton_sdk::ids::NodeUid;
 use tracing::{debug, error, info, warn};
@@ -40,6 +40,78 @@ use super::{
     now_millis, now_secs, parse_node_uid,
 };
 
+const DRAIN_ACCESS_RECHECK: Duration = Duration::from_secs(5);
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+enum DrainDisposition {
+    Applied,
+    AccessDeferred,
+}
+
+fn pending_op_authorities(op: &PendingOp) -> Result<Vec<NodeUid>, Box<dyn std::error::Error>> {
+    let uid = || -> Result<NodeUid, Box<dyn std::error::Error>> {
+        parse_node_uid(&op.uid)
+            .ok_or_else(|| Box::<dyn std::error::Error>::from("pending op has an unparseable uid"))
+    };
+    let parent = || -> Result<NodeUid, Box<dyn std::error::Error>> {
+        let parent = op
+            .parent_uid
+            .as_deref()
+            .ok_or("pending op has no parent authority")?;
+        parse_node_uid(parent).ok_or_else(|| {
+            Box::<dyn std::error::Error>::from("pending op has an unparseable parent")
+        })
+    };
+    match op.kind.as_str() {
+        OP_REVISION | OP_TRASH => Ok(vec![uid()?]),
+        OP_CREATE | OP_MKDIR => Ok(vec![parent()?]),
+        OP_RENAME => {
+            let mut authorities = vec![uid()?];
+            if let Some(json) = op.meta_json.as_deref() {
+                let meta: RenameMeta = serde_json::from_str(json)?;
+                authorities.push(
+                    parse_node_uid(&meta.original_parent_uid)
+                        .ok_or("rename op has an unparseable original parent")?,
+                );
+            } else {
+                // Rows written by 1.1.1 predate foreign shared mounts. Their
+                // source tree was necessarily owned, so the node plus desired
+                // destination are the complete available authority set.
+            }
+            authorities.push(parent()?);
+            authorities.dedup();
+            Ok(authorities)
+        }
+        other => Err(format!("unknown pending op kind {other:?}").into()),
+    }
+}
+
+fn run_authorized_drain(
+    op: &PendingOp,
+    mut require: impl FnMut(&NodeUid) -> Result<(), fuser::Errno>,
+    apply: impl FnOnce() -> Result<(), Box<dyn std::error::Error>>,
+) -> Result<DrainDisposition, Box<dyn std::error::Error>> {
+    // This check is the admission/linearization point. A downgrade that lands
+    // first defers the op; one observed afterwards does not revoke this admitted
+    // attempt. Every later queued operation rechecks. No permission lock is
+    // held across remote latency.
+    for authority in pending_op_authorities(op)? {
+        match require(&authority) {
+            Ok(()) => {}
+            Err(error) if error.code() == libc::EACCES => {
+                return Ok(DrainDisposition::AccessDeferred);
+            }
+            Err(error) => {
+                return Err(
+                    format!("drain access check failed with errno {}", error.code()).into(),
+                );
+            }
+        }
+    }
+    apply()?;
+    Ok(DrainDisposition::Applied)
+}
+
 impl Core {
     /// Drain the pending-op queue: the background half of every write
     /// (offline.md Phase 3).
@@ -69,7 +141,30 @@ impl Core {
                 self.wait_for_drain_work_or_due();
                 continue;
             };
-            if let Err(e) = self.drain_op(&op) {
+            let outcome = run_authorized_drain(
+                &op,
+                |uid| self.require_uid_writable(uid),
+                || self.drain_op(&op),
+            );
+            if matches!(outcome, Ok(DrainDisposition::AccessDeferred)) {
+                let next_attempt_at = now_millis() + DRAIN_ACCESS_RECHECK.as_millis() as i64;
+                if let Err(error) = self.db.defer_op_without_attempt(op.id, next_attempt_at) {
+                    error!(
+                        uid = %op.uid,
+                        %error,
+                        "deferring access-blocked pending operation failed"
+                    );
+                    self.wait_for_drain_work();
+                } else {
+                    debug!(
+                        uid = %op.uid,
+                        next_attempt_at,
+                        "pending operation deferred until access is writable"
+                    );
+                }
+                continue;
+            }
+            if let Err(e) = outcome {
                 let attempts = op.attempts + 1;
                 let err_str = e.to_string();
                 // Never infer that user data is disposable from an error string
@@ -252,7 +347,7 @@ impl Core {
             }
             Err(e) => return Err(e.into()),
         }
-        self.db.delete_op(op.id)?;
+        self.db.complete_trash_op(op.id, &uid)?;
         self.own_sealed_revs.lock().remove(&uid);
         self.invalidate_trash();
         self.log_activity(ActivityKind::Trash, &name, "trashed", true);
@@ -996,8 +1091,184 @@ fn is_own_self_supersede(complete: bool, remote_rev: Option<&str>, own_rev: Opti
 #[cfg(test)]
 mod tests {
     use super::*;
+    use pdfs_core::Access;
+    use pdfs_core::db::Db;
     use proton_drive_rs::NodeKind;
     use proton_drive_rs::proton_sdk::ids::{LinkId, VolumeId};
+    use std::cell::Cell;
+
+    fn pending(kind: &str) -> PendingOp {
+        PendingOp {
+            id: 0,
+            kind: kind.to_string(),
+            uid: NodeUid::new(VolumeId::from("v"), LinkId::from("node")).to_string(),
+            parent_uid: Some(NodeUid::new(VolumeId::from("v"), LinkId::from("parent")).to_string()),
+            name: Some("name".to_string()),
+            blob_path: (kind == OP_REVISION).then(|| "/staging/blob".to_string()),
+            meta_json: None,
+            created_at: 1,
+            attempts: 0,
+            last_error: None,
+            next_attempt_at: 0,
+        }
+    }
+
+    #[test]
+    fn drain_authorities_match_each_operation_kind() {
+        for kind in [OP_REVISION, OP_TRASH] {
+            assert_eq!(pending_op_authorities(&pending(kind)).unwrap().len(), 1);
+        }
+        for kind in [OP_CREATE, OP_MKDIR] {
+            let authorities = pending_op_authorities(&pending(kind)).unwrap();
+            assert_eq!(authorities.len(), 1);
+            assert_eq!(authorities[0].to_string(), "v~parent");
+        }
+        let authorities = pending_op_authorities(&pending(OP_RENAME)).unwrap();
+        assert_eq!(authorities.len(), 2);
+        assert_eq!(authorities[0].to_string(), "v~node");
+        assert_eq!(authorities[1].to_string(), "v~parent");
+    }
+
+    fn folder_node(link: &str, parent: Option<&str>) -> Node {
+        Node {
+            uid: NodeUid::new(VolumeId::from("v"), LinkId::from(link)),
+            parent_uid: parent
+                .map(|parent| NodeUid::new(VolumeId::from("v"), LinkId::from(parent))),
+            kind: NodeKind::Folder,
+            name: link.to_string(),
+            creation_time: 0,
+            modification_time: 0,
+            trashed: false,
+            is_shared: false,
+            is_shared_publicly: false,
+            signature_email: None,
+            membership: None,
+            verification: Default::default(),
+        }
+    }
+
+    #[test]
+    fn queued_cross_parent_rename_retains_viewer_source_authority_after_local_move() {
+        use std::sync::atomic::{AtomicU64, Ordering};
+
+        static N: AtomicU64 = AtomicU64::new(0);
+        let dir = std::env::temp_dir().join(format!(
+            "pdfs-drain-rename-access-{}-{}",
+            std::process::id(),
+            N.fetch_add(1, Ordering::Relaxed)
+        ));
+        std::fs::create_dir_all(&dir).unwrap();
+        let db = Db::open(&dir.join("cache.db")).unwrap();
+        let source = folder_node("source", None);
+        let destination = folder_node("destination", None);
+        let mut moved = file_node(1, 0, None);
+        moved.parent_uid = Some(destination.uid.clone());
+        for node in [&source, &destination, &moved] {
+            db.upsert_node(node).unwrap();
+        }
+        db.set_share_access(&source.uid, Access::Viewer).unwrap();
+        db.set_share_access(&destination.uid, Access::Editor)
+            .unwrap();
+
+        let mut op = pending(OP_RENAME);
+        op.uid = moved.uid.to_string();
+        op.parent_uid = Some(destination.uid.to_string());
+        op.meta_json = Some(
+            serde_json::to_string(&RenameMeta {
+                original_parent_uid: source.uid.to_string(),
+            })
+            .unwrap(),
+        );
+        let authorities = pending_op_authorities(&op).unwrap();
+        assert_eq!(authorities.len(), 3);
+        assert_eq!(authorities[1], source.uid);
+
+        let applied = Cell::new(false);
+        let disposition = run_authorized_drain(
+            &op,
+            |uid| {
+                db.effective_node_access(uid)
+                    .unwrap()
+                    .filter(|access| access.writable())
+                    .map(|_| ())
+                    .ok_or(fuser::Errno::EACCES)
+            },
+            || {
+                applied.set(true);
+                Ok(())
+            },
+        )
+        .unwrap();
+        assert_eq!(disposition, DrainDisposition::AccessDeferred);
+        assert!(!applied.get());
+        assert_eq!(
+            db.effective_node_access(&moved.uid).unwrap(),
+            Some(Access::Editor),
+            "the node's optimistic destination ancestry is writable"
+        );
+        drop(db);
+        let _ = std::fs::remove_dir_all(dir);
+    }
+
+    #[test]
+    fn viewer_deferred_drain_never_applies_or_consumes_an_attempt() {
+        use std::sync::atomic::{AtomicU64, Ordering};
+
+        static N: AtomicU64 = AtomicU64::new(0);
+        let dir = std::env::temp_dir().join(format!(
+            "pdfs-drain-access-{}-{}",
+            std::process::id(),
+            N.fetch_add(1, Ordering::Relaxed)
+        ));
+        std::fs::create_dir_all(&dir).unwrap();
+        let db = Db::open(&dir.join("cache.db")).unwrap();
+        let mut queued = pending(OP_REVISION);
+        queued.attempts = 2;
+        db.enqueue_op(&queued).unwrap();
+        let op = db.pending_ops().unwrap().remove(0);
+        let before_count = db.pending_op_counts().unwrap();
+        let applied = Cell::new(false);
+
+        let disposition = run_authorized_drain(
+            &op,
+            |_| Err(fuser::Errno::EACCES),
+            || {
+                applied.set(true);
+                Ok(())
+            },
+        )
+        .unwrap();
+        assert_eq!(disposition, DrainDisposition::AccessDeferred);
+        assert!(!applied.get(), "no API surrogate may run while read-only");
+        db.defer_op_without_attempt(op.id, 5_000).unwrap();
+
+        let retained = db.pending_ops().unwrap();
+        let after_count = db.pending_op_counts().unwrap();
+        assert_eq!(retained.len(), 1);
+        assert_eq!(retained[0].attempts, op.attempts);
+        assert_eq!(after_count.uploads, before_count.uploads);
+        assert_eq!(after_count.changes, before_count.changes);
+        drop(db);
+        let _ = std::fs::remove_dir_all(dir);
+    }
+
+    #[test]
+    fn owner_and_editor_drain_authorities_apply_normally() {
+        for access in [Access::Owner, Access::Editor] {
+            let applied = Cell::new(false);
+            let disposition = run_authorized_drain(
+                &pending(OP_REVISION),
+                |_| access.writable().then_some(()).ok_or(fuser::Errno::EACCES),
+                || {
+                    applied.set(true);
+                    Ok(())
+                },
+            )
+            .unwrap();
+            assert_eq!(disposition, DrainDisposition::Applied);
+            assert!(applied.get());
+        }
+    }
 
     fn file_node(mtime: i64, size: i64, rev: Option<&str>) -> Node {
         Node {
@@ -1019,6 +1290,7 @@ mod tests {
             is_shared: false,
             is_shared_publicly: false,
             signature_email: None,
+            membership: None,
             verification: Default::default(),
         }
     }

crates/pdfs-fuse/src/filesystem.rs

@@ -46,7 +46,7 @@ impl Filesystem for ProtonFs {
                         }
                     )
                     .then(|| (e.parent, e.uid.clone()));
-                    (self.attr(ino.0, &e.node), provisional)
+                    (self.attr(ino.0, &e.node, e.access), provisional)
                 }
                 None => {
                     reply.error(Errno::ENOENT);
@@ -79,7 +79,7 @@ impl Filesystem for ProtonFs {
             let attr = {
                 let st = fs.core.state.lock();
                 match st.entries.get(&ino.0) {
-                    Some(e) => fs.attr(ino.0, &e.node),
+                    Some(e) => fs.attr(ino.0, &e.node, e.access),
                     // Forgotten while we waited.
                     None => attr,
                 }
@@ -110,10 +110,15 @@ impl Filesystem for ProtonFs {
     }
 
     fn open(&self, _req: &Request, ino: INodeNo, flags: OpenFlags, reply: ReplyOpen) {
+        let write_requested = flags.acc_mode() != OpenAccMode::O_RDONLY;
         let (uid, base_mtime, base_size, base_revision_id) = {
             let mut st = self.core.state.lock();
             match st.entries.get_mut(&ino.0) {
                 Some(e) if e.node.is_file() => {
+                    if write_requested && !e.writable() {
+                        reply.error(Errno::EACCES);
+                        return;
+                    }
                     e.open_count = e.open_count.saturating_add(1);
                     (
                         e.uid.clone(),
@@ -315,6 +320,10 @@ impl Filesystem for ProtonFs {
         reply: ReplyCreate,
     ) {
         let parent = parent.0;
+        if let Err(error) = self.core.require_writable(parent) {
+            reply.error(error);
+            return;
+        }
         let name = match fuse_name(name) {
             Ok(name) => name,
             Err(error) => {
@@ -346,6 +355,10 @@ impl Filesystem for ProtonFs {
         _lock_owner: Option<LockOwner>,
         reply: ReplyWrite,
     ) {
+        if let Err(error) = self.core.require_writable(ino.0) {
+            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.
@@ -413,6 +426,10 @@ impl Filesystem for ProtonFs {
         _flags: Option<BsdFileFlags>,
         reply: ReplyAttr,
     ) {
+        if let Err(error) = self.core.require_writable(ino.0) {
+            reply.error(error);
+            return;
+        }
         // Only resizes change remote state; everything else (mode/owner/times) is
         // accepted and ignored so tools that chmod/utimes after writing succeed.
         if let Some(size) = size {
@@ -476,6 +493,10 @@ impl Filesystem for ProtonFs {
         mode: i32,
         reply: ReplyEmpty,
     ) {
+        if let Err(error) = self.core.require_writable(ino.0) {
+            reply.error(error);
+            return;
+        }
         let new_end = offset.saturating_add(length);
         let keep_size = (mode & 1) != 0; // FALLOC_FL_KEEP_SIZE
 
@@ -637,18 +658,7 @@ impl Filesystem for ProtonFs {
     ) {
         let (handle, unlinked_uid) = {
             let mut st = self.core.state.lock();
-            let unlinked_uid = if let Some(entry) = st.entries.get_mut(&_ino.0) {
-                entry.open_count = entry.open_count.saturating_sub(1);
-                if entry.open_count == 0 && entry.unlinked {
-                    let uid = entry.uid.clone();
-                    st.forget(&uid);
-                    Some(uid)
-                } else {
-                    None
-                }
-            } else {
-                None
-            };
+            let unlinked_uid = release_unlinked_entry(&mut st, _ino.0);
             let ino = st.handles.remove(&fh.0);
             let h = ino.and_then(|i| {
                 let aw = st.active_writes.get_mut(&i)?;
@@ -679,6 +689,10 @@ impl Filesystem for ProtonFs {
 
     fn unlink(&self, _req: &Request, parent: INodeNo, name: &OsStr, reply: ReplyEmpty) {
         let parent = parent.0;
+        if let Err(error) = self.core.require_writable(parent) {
+            reply.error(error);
+            return;
+        }
         let name_str = match fuse_name(name) {
             Ok(name) => name,
             Err(error) => {
@@ -695,6 +709,10 @@ impl Filesystem for ProtonFs {
 
     fn rmdir(&self, _req: &Request, parent: INodeNo, name: &OsStr, reply: ReplyEmpty) {
         let parent = parent.0;
+        if let Err(error) = self.core.require_writable(parent) {
+            reply.error(error);
+            return;
+        }
         let name_str = match fuse_name(name) {
             Ok(name) => name,
             Err(error) => {
@@ -720,6 +738,10 @@ impl Filesystem for ProtonFs {
         reply: ReplyEntry,
     ) {
         let parent = parent.0;
+        if let Err(error) = self.core.require_writable(parent) {
+            reply.error(error);
+            return;
+        }
         let name = match fuse_name(name) {
             Ok(name) => name,
             Err(error) => {
@@ -748,6 +770,14 @@ impl Filesystem for ProtonFs {
     ) {
         let parent = parent.0;
         let newparent = newparent.0;
+        if let Err(error) = self
+            .core
+            .require_writable(parent)
+            .and_then(|()| self.core.require_writable(newparent))
+        {
+            reply.error(error);
+            return;
+        }
         let name = match fuse_name(name) {
             Ok(name) => name,
             Err(error) => {
@@ -771,6 +801,19 @@ impl Filesystem for ProtonFs {
         });
     }
 
+    fn access(&self, _req: &Request, ino: INodeNo, mask: AccessFlags, reply: ReplyEmpty) {
+        let state = self.core.state.lock();
+        let Some(entry) = state.entries.get(&ino.0) else {
+            reply.error(Errno::ENOENT);
+            return;
+        };
+        if !access_allowed(entry.node.is_folder(), entry.access, mask) {
+            reply.error(Errno::EACCES);
+        } else {
+            reply.ok();
+        }
+    }
+
     fn getxattr(&self, _req: &Request, ino: INodeNo, name: &OsStr, size: u32, reply: ReplyXattr) {
         // Always off the dispatch loop: a miss goes to the wire, and a lister
         // that stats a directory issues one of these per file per advertised
@@ -935,6 +978,11 @@ pub struct ProtonFs {
     gid: u32,
 }
 
+pub(crate) fn access_allowed(is_dir: bool, access: Access, mask: AccessFlags) -> bool {
+    (!mask.contains(AccessFlags::W_OK) || access.writable())
+        && (!mask.contains(AccessFlags::X_OK) || is_dir)
+}
+
 impl ProtonFs {
     /// Build the filesystem rooted at `root` (the user's My Files folder).
     pub(super) fn new(core: Core, root: Node) -> Self {
@@ -944,12 +992,14 @@ impl ProtonFs {
                 warn!(uid = %root.uid, error = %e, "db upsert root failed");
             }
             st.by_uid.insert(root.uid.clone(), ROOT_INO);
+            let access = st.access_for_node(ROOT_INO, &root);
             st.entries.insert(
                 ROOT_INO,
                 Entry {
                     uid: root.uid.clone(),
                     parent: ROOT_INO,
                     node: root,
+                    access,
                     lookup_count: 1,
                     open_count: 0,
                     unlinked: false,
@@ -991,7 +1041,7 @@ impl ProtonFs {
                                 }
                             )
                             .then(|| (e.parent, e.uid.clone()));
-                            (ino, self.attr(ino, &e.node), provisional)
+                            (ino, self.attr(ino, &e.node, e.access), provisional)
                         })
                 })
             })
@@ -1023,7 +1073,7 @@ impl ProtonFs {
             let st = self.core.state.lock();
             st.entries
                 .get(&ino)
-                .map_or(attr, |e| self.attr(ino, &e.node))
+                .map_or(attr, |e| self.attr(ino, &e.node, e.access))
         };
         reply.entry(&TTL, &attr, Generation(0));
     }
@@ -1065,11 +1115,12 @@ impl ProtonFs {
         reply.ok();
     }
 
-    fn attr(&self, ino: u64, node: &Node) -> FileAttr {
-        let (kind, perm) = match node.kind {
-            NodeKind::Folder => (FileType::Directory, 0o755),
-            NodeKind::File { .. } => (FileType::RegularFile, 0o644),
+    fn attr(&self, ino: u64, node: &Node, access: Access) -> FileAttr {
+        let kind = match node.kind {
+            NodeKind::Folder => FileType::Directory,
+            NodeKind::File { .. } => FileType::RegularFile,
         };
+        let perm = perm_bits(node.is_folder(), access);
         let size = node_size(node);
         let mtime = unix_secs(node.modification_time);
         let crtime = unix_secs(node.creation_time);
@@ -1097,6 +1148,10 @@ impl ProtonFs {
     /// subtrees, so an `rmdir` of a non-empty dir behaves the same).
     /// The body of [`Filesystem::create`], run off the dispatch loop.
     fn serve_create(&self, parent: u64, name: &str, reply: ReplyCreate) {
+        if let Err(error) = self.core.require_writable(parent) {
+            reply.error(error);
+            return;
+        }
         if let Err(e) = self.core.ensure_children(parent) {
             reply.error(e);
             return;
@@ -1128,6 +1183,10 @@ impl ProtonFs {
         let node =
             if !transient && self.core.online.load(Ordering::Relaxed) && !is_local_uid(&parent_uid)
             {
+                if let Err(error) = self.core.require_uid_writable(&parent_uid) {
+                    reply.error(error);
+                    return;
+                }
                 // Create an empty file on the remote so it has a real uid immediately;
                 // written bytes are buffered and sealed as a new revision on close.
                 let new_uid = match self.core.rt.block_on(self.core.client.upload_file(
@@ -1211,7 +1270,10 @@ impl ProtonFs {
         });
         aw.open_count += 1;
         st.handles.insert(fh, ino);
-        let attr = self.attr(ino, &st.entries.get(&ino).unwrap().node);
+        let entry = st.entries.get(&ino).unwrap();
+        let attr = self.attr(ino, &entry.node, entry.access);
+        drop(st);
+        self.core.flush_access_changes();
         reply.created(
             &TTL,
             &attr,
@@ -1223,6 +1285,10 @@ impl ProtonFs {
 
     /// The body of [`Filesystem::mkdir`], run off the dispatch loop.
     fn serve_mkdir(&self, parent: u64, name: &str, reply: ReplyEntry) {
+        if let Err(error) = self.core.require_writable(parent) {
+            reply.error(error);
+            return;
+        }
         if let Err(e) = self.core.ensure_children(parent) {
             reply.error(e);
             return;
@@ -1245,6 +1311,10 @@ impl ProtonFs {
         // queued — the folder becomes a placeholder that the drain turns into a
         // real one (offline.md Phase 3b).
         let node = if self.core.online.load(Ordering::Relaxed) && !is_local_uid(&parent_uid) {
+            if let Err(error) = self.core.require_uid_writable(&parent_uid) {
+                reply.error(error);
+                return;
+            }
             let new_uid =
                 match self
                     .core
@@ -1292,12 +1362,19 @@ impl ProtonFs {
                 warn!(%uid, error = %e, "db set_listed(true) failed for local folder");
             }
         }
-        let attr = self.attr(ino, &st.entries.get(&ino).unwrap().node);
+        let entry = st.entries.get(&ino).unwrap();
+        let attr = self.attr(ino, &entry.node, entry.access);
+        drop(st);
+        self.core.flush_access_changes();
         reply.entry(&TTL, &attr, Generation(0));
     }
 
     /// The body of [`Filesystem::unlink`], run off the dispatch loop.
     fn serve_unlink(&self, parent: u64, name_str: &str, reply: ReplyEmpty) {
+        if let Err(error) = self.core.require_writable(parent) {
+            reply.error(error);
+            return;
+        }
         if let Ok((ino, _)) = self.core.lookup_child(parent, name_str) {
             let st = self.core.state.lock();
             if let Some(entry) = st.entries.get(&ino)
@@ -1312,6 +1389,10 @@ impl ProtonFs {
 
     /// The body of [`Filesystem::rmdir`], run off the dispatch loop.
     fn serve_rmdir(&self, parent: u64, name_str: &str, reply: ReplyEmpty) {
+        if let Err(error) = self.core.require_writable(parent) {
+            reply.error(error);
+            return;
+        }
         if let Ok((ino, _)) = self.core.lookup_child(parent, name_str) {
             {
                 let st = self.core.state.lock();
@@ -1348,10 +1429,18 @@ impl ProtonFs {
         reply: ReplyEmpty,
     ) {
         let was_unlinked = unlinked_uid.is_some();
-        if let Some(uid) = unlinked_uid {
-            self.core.discard_queued_ops(&uid);
-            self.core.cache.evict(&uid);
-            self.core.evict_reader(&uid);
+        if let Some(uid) = unlinked_uid
+            && release_can_discard_unlinked(&self.core.db, &uid)
+        {
+            if let Err(error) = self.core.discard_queued_ops(&uid) {
+                warn!(%uid, ?error, "queued-op cleanup failed; retaining unlinked state");
+            } else {
+                if let Err(error) = self.core.db.delete_node(&uid) {
+                    warn!(%uid, %error, "deleting released unlinked node state failed");
+                }
+                self.core.cache.evict(&uid);
+                self.core.evict_reader(&uid);
+            }
         }
         // Hand the bytes to the queue rather than uploading them here: the
         // scratch file is the only copy of what was just written, and blocking
@@ -1366,6 +1455,7 @@ impl ProtonFs {
                 {
                     warn!(path = %h.path.display(), error = %e, "discarding unlinked scratch file failed");
                 }
+                self.core.cache.clear_scratch_durable(&h.path);
                 reply.ok();
             }
             (Some(h), false) => match self.core.queue_revision(&h) {
@@ -1386,6 +1476,14 @@ impl ProtonFs {
         flags: RenameFlags,
         reply: ReplyEmpty,
     ) {
+        if let Err(error) = self
+            .core
+            .require_writable(parent)
+            .and_then(|()| self.core.require_writable(newparent))
+        {
+            reply.error(error);
+            return;
+        }
         let (ino, uid) = match self.core.lookup_child(parent, name) {
             Ok(x) => x,
             Err(e) => {
@@ -1413,11 +1511,11 @@ impl ProtonFs {
             reply.error(e);
             return;
         }
-        let new_parent_uid = {
+        let (old_parent_uid, new_parent_uid) = {
             let st = self.core.state.lock();
-            match st.entries.get(&newparent) {
-                Some(e) => e.uid.clone(),
-                None => {
+            match (st.entries.get(&parent), st.entries.get(&newparent)) {
+                (Some(old), Some(new)) => (old.uid.clone(), new.uid.clone()),
+                _ => {
                     reply.error(Errno::ENOENT);
                     return;
                 }
@@ -1446,7 +1544,7 @@ impl ProtonFs {
                 return;
             }
         };
-        if let Some((victim_ino, victim_uid)) = &victim {
+        let replacement_authorized = if let Some((victim_ino, victim_uid)) = &victim {
             if flags.contains(RenameFlags::RENAME_NOREPLACE) {
                 reply.error(Errno::EEXIST);
                 return;
@@ -1490,11 +1588,23 @@ impl ProtonFs {
                 reply.error(e);
                 return;
             }
+            if let Err(error) = require_rename_access(
+                |authority| self.core.require_uid_writable(authority),
+                &uid,
+                &old_parent_uid,
+                &new_parent_uid,
+            ) {
+                reply.error(error);
+                return;
+            }
             if let Err(e) = self.core.remove_replaced(victim_uid, newname) {
                 reply.error(e);
                 return;
             }
-        }
+            true
+        } else {
+            false
+        };
         // A node whose own creation is still queued has no server-side identity
         // to rename: the queued op *is* the node, so rewriting its target is the
         // whole rename. Nothing reaches the API, which is why this works offline
@@ -1557,10 +1667,26 @@ impl ProtonFs {
             newparent != parent,
             newname != name,
         ) {
-            match self
-                .core
-                .queue_rename(ino, &uid, newparent, &new_parent_uid, newname)
-            {
+            let queued = if replacement_authorized {
+                self.core.queue_rename_authorized(
+                    ino,
+                    &uid,
+                    &old_parent_uid,
+                    newparent,
+                    &new_parent_uid,
+                    newname,
+                )
+            } else {
+                self.core.queue_rename(
+                    ino,
+                    &uid,
+                    &old_parent_uid,
+                    newparent,
+                    &new_parent_uid,
+                    newname,
+                )
+            };
+            match queued {
                 Ok(()) => {
                     // Send the rename response first. Kernel-side rename cache
                     // updates happen while processing that response; notifying
@@ -1588,6 +1714,16 @@ impl ProtonFs {
         // A failure past this point has already trashed any node the rename was
         // replacing, so put it back rather than leaving the caller with neither
         // the source moved nor the destination intact.
+        if let Err(error) = require_rename_access(
+            |authority| self.core.require_uid_writable(authority),
+            &uid,
+            &old_parent_uid,
+            &new_parent_uid,
+        ) {
+            self.core.restore_replaced(victim.as_ref(), newname);
+            reply.error(error);
+            return;
+        }
         if newname != name
             && let Err(e) = self
                 .core
@@ -1655,7 +1791,7 @@ impl ProtonFs {
         let st = self.core.state.lock();
         match st.entries.get(&ino) {
             Some(e) => {
-                let attr = self.attr(ino, &e.node);
+                let attr = self.attr(ino, &e.node, e.access);
                 reply.attr(&TTL, &attr);
             }
             None => reply.error(Errno::ENOENT),
@@ -1663,6 +1799,10 @@ impl ProtonFs {
     }
 
     fn trash_child(&self, parent: u64, name: &str, reply: ReplyEmpty) {
+        if let Err(error) = self.core.require_writable(parent) {
+            reply.error(error);
+            return;
+        }
         let (ino, uid) = match self.core.lookup_child(parent, name) {
             Ok(x) => x,
             Err(e) => {
@@ -1681,8 +1821,9 @@ impl ProtonFs {
         // it just means its queued creation is no longer wanted. This works
         // offline, which the remote path below cannot (offline.md Phase 3b).
         if is_local_uid(&uid) {
-            if !open_now {
-                self.core.discard_queued_ops(&uid);
+            if !open_now && let Err(error) = self.core.discard_queued_ops(&uid) {
+                reply.error(error);
+                return;
             }
             self.core.state.lock().forget_or_unlink(&uid);
             debug!(%uid, name, "deleted a node that had not been created remotely yet");
@@ -1694,14 +1835,15 @@ impl ProtonFs {
         // command returns (offline.md Phase 3b).
         if !self.core.online.load(Ordering::Relaxed) {
             match self.core.queue_trash(&uid, name) {
-                Ok(()) => {
-                    self.core.state.lock().forget_or_unlink(&uid);
-                    reply.ok();
-                }
+                Ok(()) => reply.ok(),
                 Err(e) => reply.error(e),
             }
             return;
         }
+        if let Err(e) = self.core.require_uid_writable(&uid) {
+            reply.error(e);
+            return;
+        }
         if let Err(e) = self
             .core
             .rt
@@ -1718,7 +1860,9 @@ impl ProtonFs {
         self.core.hidden.lock().insert(uid.clone());
         self.core.state.lock().forget_or_unlink(&uid);
         if !open_now {
-            self.core.discard_queued_ops(&uid);
+            if let Err(error) = self.core.discard_queued_ops(&uid) {
+                warn!(%uid, ?error, "remote trash landed but queued-op cleanup failed");
+            }
             self.core.cache.evict(&uid);
             self.core.evict_reader(&uid);
         }

crates/pdfs-fuse/src/mount.rs

@@ -28,10 +28,101 @@ pub(crate) fn is_stale_mount(path: &Path) -> bool {
     )
 }
 
-/// A secondary (on-demand sync folder) FUSE session, paired with its FUSE
-/// connection id so teardown can abort a mid-transfer connection rather than
-/// block on it. See [`Core::mounts`] and [`umount_session_unblocked`].
-pub(super) type SecondaryMount = (BackgroundSession, Option<u32>);
+/// A secondary (on-demand sync folder) FUSE session and the exact liveness flag
+/// published with its forked inode state.
+///
+/// Keeping these together makes every teardown mark the fork unroutable before
+/// unmounting, including paths that can block on an in-flight FUSE request.
+pub(super) struct SecondaryMount {
+    session: BackgroundSession,
+    conn: Option<u32>,
+    session_live: Arc<AtomicBool>,
+}
+
+#[derive(Clone, Copy, Debug, PartialEq, Eq)]
+pub(super) enum SecondaryInsertRejection {
+    Closed,
+    Duplicate,
+}
+
+/// Secondary sessions and the daemon-wide gate controlling whether newly
+/// spawned sessions may become visible. The gate and map share one lock so
+/// shutdown cannot race an insertion between checking and publishing.
+pub(super) struct SecondaryMountRegistry<T> {
+    accepting: bool,
+    entries: HashMap<i64, T>,
+}
+
+impl<T> Default for SecondaryMountRegistry<T> {
+    fn default() -> Self {
+        Self {
+            accepting: false,
+            entries: HashMap::new(),
+        }
+    }
+}
+
+impl<T> SecondaryMountRegistry<T> {
+    pub(super) fn open(&mut self) {
+        self.accepting = true;
+    }
+
+    pub(super) fn is_accepting(&self) -> bool {
+        self.accepting
+    }
+
+    pub(super) fn close(&mut self) {
+        self.accepting = false;
+    }
+
+    pub(super) fn insert(
+        &mut self,
+        id: i64,
+        mount: T,
+    ) -> Result<(), (SecondaryInsertRejection, T)> {
+        if !self.accepting {
+            return Err((SecondaryInsertRejection::Closed, mount));
+        }
+        if self.entries.contains_key(&id) {
+            return Err((SecondaryInsertRejection::Duplicate, mount));
+        }
+        self.entries.insert(id, mount);
+        Ok(())
+    }
+
+    pub(super) fn remove(&mut self, id: &i64) -> Option<T> {
+        self.entries.remove(id)
+    }
+
+    pub(super) fn contains_key(&self, id: &i64) -> bool {
+        self.entries.contains_key(id)
+    }
+
+    pub(super) fn close_and_drain(&mut self) -> Vec<(i64, T)> {
+        self.close();
+        self.entries.drain().collect()
+    }
+}
+
+impl SecondaryMount {
+    pub(super) fn new(
+        session: BackgroundSession,
+        conn: Option<u32>,
+        session_live: Arc<AtomicBool>,
+    ) -> Self {
+        Self {
+            session,
+            conn,
+            session_live,
+        }
+    }
+
+    pub(super) fn teardown(self) -> std::io::Result<()> {
+        teardown_session(&self.session_live, || {
+            umount_session_unblocked(self.session, self.conn)
+        })
+    }
+}
 
 /// The kernel's id for the FUSE connection backing the mount at `mountpoint` —
 /// the directory name under `/sys/fs/fuse/connections`, which is the minor
@@ -152,6 +243,71 @@ pub struct MountOptions {
     pub sweep_mode: SweepMode,
 }
 
+/// Spawn one FUSE session rooted at an arbitrary remote node.
+///
+/// Primary My Files and secondary on-demand device locations use this same
+/// construction path so mount options, stale-mount recovery, registry
+/// liveness, and notifier ownership cannot drift apart. Each caller owns its
+/// state/path registration and performs it exactly once before calling here.
+pub(super) fn spawn_session(
+    core: &Core,
+    mountpoint: &Path,
+    root: Node,
+) -> std::io::Result<BackgroundSession> {
+    let mut config = Config::default();
+    config.mount_options = vec![
+        MountOption::FSName("protondrive".to_string()),
+        MountOption::Subtype("protondrive".to_string()),
+        MountOption::DefaultPermissions,
+    ];
+
+    clear_stale_mount(mountpoint);
+    info!(mountpoint = %mountpoint.display(), "mounting Proton Drive location");
+    let fs = ProtonFs::new(core.clone(), root);
+    if core.primary {
+        // Only My Files rehydrates the daemon-wide node cache. A secondary
+        // inode space is rooted at one device subtree and must not import every
+        // unrelated persisted node.
+        core.hydrate();
+    }
+    let session = Session::new(fs, mountpoint, &config)?.spawn()?;
+    let _ = core.notifier.set(session.notifier());
+    core.session_live.store(true, Ordering::Release);
+    Ok(session)
+}
+
+/// Make a session unroutable before beginning any teardown that may block.
+fn teardown_session<T>(session_live: &AtomicBool, teardown: impl FnOnce() -> T) -> T {
+    session_live.store(false, Ordering::Release);
+    teardown()
+}
+
+impl Core {
+    /// Resolve the primary share id away from startup and publish it only if the
+    /// projected root has not changed while the request was in flight.
+    pub(crate) fn repair_primary_share_id(&self, root_uid: &NodeUid) {
+        match self.rt.block_on(self.client.context_share_id(root_uid)) {
+            Ok(share_id) => {
+                match self
+                    .db
+                    .mount_repair_my_files_share_id(&root_uid.to_string(), &share_id.to_string())
+                {
+                    Ok(true) => debug!(%root_uid, "repaired My Files share id"),
+                    Ok(false) => {
+                        debug!(%root_uid, "discarded stale My Files share-id result");
+                    }
+                    Err(error) => {
+                        warn!(%root_uid, error = %error, "persist My Files share id failed");
+                    }
+                }
+            }
+            Err(error) => {
+                debug!(%root_uid, error = %error, "resolve My Files share id failed");
+            }
+        }
+    }
+}
+
 /// Mount the filesystem at `mountpoint` and block until it is unmounted or the
 /// daemon is asked to stop.
 ///
@@ -179,6 +335,11 @@ pub fn mount(
     } = options;
     let (root, online) = fetch_or_recall_root(&client, &rt, &db)?;
     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}")))?;
+    let share_access = db
+        .all_share_access()
+        .map_err(|error| std::io::Error::other(format!("load shared access: {error}")))?;
 
     // The folder-sync engine (devices.md Phase 2) runs on its own thread and is
     // nudged over this channel; the sender lives in Core so control-socket
@@ -188,6 +349,8 @@ pub fn mount(
     let core = Core {
         client: client.clone(),
         rt: rt.clone(),
+        primary_root_uid: root.uid.clone(),
+        primary: true,
         state: Arc::new(Mutex::new(State {
             entries: HashMap::new(),
             by_uid: HashMap::new(),
@@ -196,6 +359,8 @@ pub fn mount(
             active_writes: HashMap::new(),
             handles: HashMap::new(),
             next_fh: 1,
+            access_changes: HashSet::new(),
+            share_access,
             db: db.clone(),
         })),
         cache: Arc::new(cache),
@@ -203,12 +368,16 @@ pub fn mount(
         stream_ring: Arc::new(Mutex::new(StreamRing::default())),
         workers: Arc::new(Workers::new(FUSE_WORKERS)?),
         db,
+        shared_publication: Arc::new(Mutex::new(())),
+        shared_generation: Arc::new(AtomicU64::new(0)),
+        shared_refresh_deadlines: Arc::new(Mutex::new(SharedRefreshDeadlines::default())),
         online: Arc::new(AtomicBool::new(online)),
         pending: Arc::new(Mutex::new(HashMap::new())),
         hidden: Arc::new(Mutex::new(HashSet::new())),
         drain_wake: Arc::new((Mutex::new(false), Condvar::new())),
         timeline_refreshing: Arc::new(AtomicBool::new(false)),
         trash_refreshing: Arc::new(AtomicBool::new(false)),
+        trash_progress: Arc::new(tokio::sync::Notify::new()),
         conflict_notified: Arc::new(Mutex::new(HashSet::new())),
         sweep_mode,
         own_sealed_revs: Arc::new(Mutex::new(HashMap::new())),
@@ -217,17 +386,18 @@ pub fn mount(
         no_thumbnail: Arc::new(Mutex::new(HashMap::new())),
         size_upgrades: Arc::new(Mutex::new(HashMap::new())),
         notifier: Arc::new(OnceLock::new()),
+        session_live: Arc::new(AtomicBool::new(false)),
         transfers: TransferRegistry::new(),
         indexing: Arc::new(AtomicBool::new(false)),
         sync_progress: Arc::new(Mutex::new(HashMap::new())),
         sync_tx,
-        mounts: Arc::new(Mutex::new(HashMap::new())),
+        mounts: Arc::new(Mutex::new(SecondaryMountRegistry::default())),
         sync_locks: Arc::new(Mutex::new(HashMap::new())),
         states: Arc::new(StateRegistry::default()),
     };
     // Before anything can queue work against it: the drain thread below reaches
     // every mount's inode space through this registry, not through `core.state`.
-    core.register_state();
+    core.register_state(mountpoint);
 
     // Writes queued by a previous run (or left behind by a crash) are still owed
     // an upload, and reads must be served from their staged blobs until they land.
@@ -271,16 +441,6 @@ pub fn mount(
             .spawn(move || core.run_online_probe())?;
     }
 
-    // Re-establish on-demand mounts left over from a previous run (devices.md
-    // Phase 4). On its own thread: each remount fetches a remote node, and we
-    // must not block the main mount below on the network.
-    {
-        let core = core.clone();
-        std::thread::Builder::new()
-            .name("pdfs-restore-ondemand".into())
-            .spawn(move || core.restore_ondemand_mounts())?;
-    }
-
     // Keep the launcher prompt's "This computer" index fresh. Its own thread:
     // the walk is I/O-heavy and must never sit in front of a FUSE callback.
     {
@@ -293,18 +453,6 @@ pub fn mount(
             .spawn(move || run_local_index(db, indexing, transfers, mountpoint))?;
     }
 
-    let mut config = Config::default();
-    config.mount_options = vec![
-        MountOption::FSName("protondrive".to_string()),
-        MountOption::Subtype("protondrive".to_string()),
-        MountOption::DefaultPermissions,
-    ];
-
-    // A crashed previous run can leave the kernel mount in place, which makes
-    // the fresh mount below fail with EBUSY. Lazily detach any leftover first.
-    clear_stale_mount(mountpoint);
-    info!(mountpoint = %mountpoint.display(), "mounting Proton Drive");
-
     // Bind the control socket before the FUSE session takes over the thread. A
     // stale socket file from a previous run would block the bind, so clear it.
     let _ = std::fs::remove_file(control_socket);
@@ -321,32 +469,70 @@ pub fn mount(
             "control socket permissions: {e}"
         )));
     }
-    {
-        let core = core.clone();
-        let username = username.clone();
-        let mountpoint = mountpoint.to_path_buf();
-        std::thread::Builder::new()
-            .name("pdfs-control".into())
-            .spawn(move || run_control_socket(core, username, mountpoint, listener))?;
-    }
-
-    let fs = ProtonFs::new(core.clone(), root);
-    // Warm the in-memory maps from the DB so a cold start serves previously
-    // seen metadata without re-hitting the API (plan.md P1).
-    core.hydrate();
-
-    // Build the session explicitly (not `mount2`) so we can grab a `Notifier`
-    // for the event task. `spawn` runs the session loop on its own background
-    // thread; we then wait here for either a stop signal or the mount ending.
-    let bg = Session::new(fs, mountpoint, &config)?.spawn()?;
+    // Do not accept control requests until `spawn_session` has transitioned the
+    // primary registration to live. The listener may queue a connection during
+    // this short window, but its handler cannot observe `mounted = false`.
+    let bg = match spawn_session(&core, mountpoint, root) {
+        Ok(session) => session,
+        Err(error) => {
+            let _ = std::fs::remove_file(control_socket);
+            return Err(error);
+        }
+    };
+    core.mounts.lock().open();
     // The connection id, captured now while the mount is live, so a stop signal
     // mid-transfer can abort it rather than block `join` (see `abort_fuse_connection`).
     let main_conn = fuse_connection_id(mountpoint);
-    let notifier = bg.notifier();
-    // Same channel, kept on the `Core` so background work (a size upgrade, say)
-    // can invalidate kernel-cached metadata without threading a handle through.
-    let _ = core.notifier.set(notifier.clone());
+    {
+        let control_core = core.clone();
+        let username = username.clone();
+        let mountpoint = mountpoint.to_path_buf();
+        if let Err(error) = std::thread::Builder::new()
+            .name("pdfs-control".into())
+            .spawn(move || run_control_socket(control_core, username, mountpoint, listener))
+        {
+            let secondaries = core.mounts.lock().close_and_drain();
+            for (id, mount) in secondaries {
+                if let Err(unmount_error) = mount.teardown() {
+                    warn!(id, error = %unmount_error, "secondary teardown after control startup failure failed");
+                }
+            }
+            if let Err(unmount_error) = teardown_session(&core.session_live, || {
+                umount_session_unblocked(bg, main_conn)
+            }) {
+                warn!(error = %unmount_error, "unmount after control startup failure failed");
+            }
+            let _ = std::fs::remove_file(control_socket);
+            return Err(error);
+        }
+    }
+    // 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
+    // fetch to observe that closure, and then drain a stable registry.
+    let restore_worker = {
+        let restore_core = core.clone();
+        match std::thread::Builder::new()
+            .name("pdfs-restore-ondemand".into())
+            .spawn(move || restore_core.restore_ondemand_mounts())
+        {
+            Ok(worker) => Some(worker),
+            Err(error) => {
+                warn!(%error, "start on-demand restore worker failed");
+                None
+            }
+        }
+    };
     rt.spawn(run_event_sync(client, scope, core.clone()));
+    if online {
+        let repair_core = core.clone();
+        let root_uid = core.primary_root_uid.clone();
+        if let Err(error) = std::thread::Builder::new()
+            .name("pdfs-share-id".into())
+            .spawn(move || repair_core.repair_primary_share_id(&root_uid))
+        {
+            warn!(%error, "start My Files share-id repair failed");
+        }
+    }
 
     // Stop signals (SIGTERM from `systemctl --user stop`, SIGINT from Ctrl-C)
     // are delivered onto the async runtime; bridge them onto a sync channel so
@@ -385,7 +571,10 @@ pub fn mount(
         match sig_rx.recv_timeout(Duration::from_millis(500)) {
             Ok(()) => {
                 info!("stop requested; unmounting");
-                if let Err(e) = umount_session_unblocked(bg, main_conn) {
+                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::Shutdown;
@@ -393,7 +582,8 @@ pub fn mount(
             Err(std::sync::mpsc::RecvTimeoutError::Timeout) => {
                 if bg.guard.is_finished() {
                     info!("mount ended externally");
-                    if let Err(e) = bg.join() {
+                    core.mounts.lock().close();
+                    if let Err(e) = teardown_session(&core.session_live, || bg.join()) {
                         warn!(error = %e, "session join failed");
                     }
                     break MountOutcome::Unmounted;
@@ -401,7 +591,8 @@ pub fn mount(
             }
             Err(std::sync::mpsc::RecvTimeoutError::Disconnected) => {
                 // Signal task gone (failed to install); fall back to join.
-                let _ = bg.join();
+                core.mounts.lock().close();
+                let _ = teardown_session(&core.session_live, || bg.join());
                 break MountOutcome::Unmounted;
             }
         }
@@ -409,9 +600,14 @@ pub fn mount(
 
     // Unmount every on-demand sync folder too, or the kernel mounts linger as
     // stale and the next start fails with EBUSY (devices.md Phase 3).
-    let secondaries: Vec<_> = core.mounts.lock().drain().collect();
-    for (id, (session, conn)) in secondaries {
-        if let Err(e) = umount_session_unblocked(session, conn) {
+    if let Some(worker) = restore_worker
+        && worker.join().is_err()
+    {
+        warn!("on-demand restore worker panicked");
+    }
+    let secondaries = core.mounts.lock().close_and_drain();
+    for (id, mount) in secondaries {
+        if let Err(e) = mount.teardown() {
             warn!(id, error = %e, "unmount on-demand folder failed");
         }
     }
@@ -419,3 +615,41 @@ pub fn mount(
     let _ = std::fs::remove_file(control_socket);
     Ok(outcome)
 }
+
+#[cfg(test)]
+mod tests {
+    use std::sync::atomic::{AtomicBool, Ordering};
+
+    use super::{SecondaryInsertRejection, SecondaryMountRegistry, teardown_session};
+
+    #[test]
+    fn session_is_unroutable_before_teardown_starts() {
+        let live = AtomicBool::new(true);
+        teardown_session(&live, || {
+            assert!(
+                !live.load(Ordering::Acquire),
+                "teardown must never run while the registry still reports mounted"
+            );
+        });
+    }
+
+    #[test]
+    fn secondary_registry_rejects_closed_and_duplicate_insertions() {
+        let mut mounts = SecondaryMountRegistry::default();
+        assert_eq!(
+            mounts.insert(7, "closed"),
+            Err((SecondaryInsertRejection::Closed, "closed"))
+        );
+
+        mounts.open();
+        assert_eq!(mounts.insert(7, "first"), Ok(()));
+        assert_eq!(
+            mounts.insert(7, "duplicate"),
+            Err((SecondaryInsertRejection::Duplicate, "duplicate"))
+        );
+        assert!(mounts.contains_key(&7));
+
+        assert_eq!(mounts.close_and_drain(), vec![(7, "first")]);
+        assert!(!mounts.is_accepting());
+    }
+}

crates/pdfs-fuse/src/profile.rs

@@ -12,6 +12,7 @@ use std::sync::OnceLock;
 use std::sync::atomic::{AtomicBool, Ordering};
 
 use pdfs_core::control::RestorableFolder;
+use pdfs_core::mounts::MountMode;
 use pdfs_core::profile::{PROFILE_FILE_NAME, PROFILE_VERSION, Profile, ProfileFolder, ProfilePin};
 use pdfs_core::{CoreError, CoreResult};
 use proton_drive_rs::proton_sdk::ids::NodeUid;
@@ -133,7 +134,7 @@ impl Core {
                 local_path: f.local_path,
                 // A queued switch is where the user asked the folder to be, so
                 // that is what the next machine should set up.
-                mode: f.pending_mode.unwrap_or(f.mode),
+                mode: MountMode::from(f.pending_mode.unwrap_or(f.mode).as_str()),
             })
             .collect();
         let pins = self
@@ -267,7 +268,7 @@ impl Core {
                     name: n.name,
                     local_path: proposed.to_string_lossy().to_string(),
                     mode: saved
-                        .map(|f| f.mode.clone())
+                        .map(|f| f.mode.to_string())
                         .unwrap_or_else(|| "mirror".into()),
                 }
             })
@@ -319,10 +320,10 @@ impl Core {
                 skipped.push(format!("{}: {e}", item.local_path));
                 continue;
             }
-            let mode = match item.mode.as_str() {
-                "mirror" | "ondemand" => item.mode.as_str(),
-                other => {
-                    skipped.push(format!("{}: unknown mode {other}", item.local_path));
+            let mode = match restore_mode(&item.mode) {
+                Some(mode) => mode,
+                None => {
+                    skipped.push(format!("{}: unknown mode {}", item.local_path, item.mode));
                     continue;
                 }
             };
@@ -333,7 +334,7 @@ impl Core {
             // `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.
-            if mode == "ondemand" {
+            if mode == MountMode::OnDemand {
                 let _ = self.request_sync_folder_mode(id, "ondemand");
             }
             let _ = self.sync_tx.send(sync::SyncMsg::Reconcile(id));
@@ -350,6 +351,17 @@ impl Core {
     }
 }
 
+/// Accept only modes this build can safely restore. `MountMode` itself is
+/// tolerant so a future value does not reject the whole profile; the folder
+/// carrying that value is skipped here with the message assembled above.
+fn restore_mode(value: &str) -> Option<MountMode> {
+    match MountMode::from(value) {
+        MountMode::Mirror => Some(MountMode::Mirror),
+        MountMode::OnDemand => Some(MountMode::OnDemand),
+        MountMode::Unknown => None,
+    }
+}
+
 /// Whether a path recorded on another machine can be reused verbatim here.
 ///
 /// Requires the *parent* to exist: `~/Documents` on a machine with the same
@@ -382,6 +394,14 @@ mod tests {
         assert!(!path_is_usable_here(Path::new("relative/path")));
     }
 
+    #[test]
+    fn unknown_profile_mode_is_skipped_without_rejecting_known_modes() {
+        assert_eq!(restore_mode("mirror"), Some(MountMode::Mirror));
+        assert_eq!(restore_mode("ondemand"), Some(MountMode::OnDemand));
+        assert_eq!(restore_mode("streaming"), None);
+        assert_eq!(restore_mode("unknown"), None);
+    }
+
     /// A path whose parent exists but which does not itself is exactly the
     /// restore case — the directory is about to be created.
     #[test]

crates/pdfs-fuse/src/sharing.rs

@@ -57,11 +57,33 @@ impl Core {
         message: Option<&str>,
     ) -> CoreResult<(usize, usize)> {
         let (_ino, uid) = self.resolve(rel)?;
+        self.share_node_for_uid(&uid, emails, role, message)
+    }
+
+    /// [`Core::share_node`] for a node addressed through any daemon location.
+    pub(crate) fn share_node_by_uid(
+        &self,
+        uid: &str,
+        emails: &[String],
+        role: &str,
+        message: Option<&str>,
+    ) -> CoreResult<(usize, usize)> {
+        let uid = self.resolve_anywhere(uid)?;
+        self.share_node_for_uid(&uid, emails, role, message)
+    }
+
+    fn share_node_for_uid(
+        &self,
+        uid: &NodeUid,
+        emails: &[String],
+        role: &str,
+        message: Option<&str>,
+    ) -> CoreResult<(usize, usize)> {
         let role = role_from_str(role)?;
         let invitees: Vec<(String, MemberRole)> =
             emails.iter().map(|e| (e.clone(), role)).collect();
         self.rt
-            .block_on(self.client.invite_users(&uid, &invitees, message))
+            .block_on(self.client.invite_users(uid, &invitees, message))
             .map_err(|e| CoreError::from_api(&e, "share"))
     }
 
@@ -71,11 +93,26 @@ impl Core {
         rel: &Path,
     ) -> CoreResult<(Vec<ShareEntry>, Option<PublicLinkInfo>)> {
         let (_ino, uid) = self.resolve(rel)?;
+        self.list_share_for_uid(&uid)
+    }
 
+    /// [`Core::list_share`] for a node addressed through any daemon location.
+    pub(crate) fn list_share_by_uid(
+        &self,
+        uid: &str,
+    ) -> CoreResult<(Vec<ShareEntry>, Option<PublicLinkInfo>)> {
+        let uid = self.resolve_anywhere(uid)?;
+        self.list_share_for_uid(&uid)
+    }
+
+    fn list_share_for_uid(
+        &self,
+        uid: &NodeUid,
+    ) -> CoreResult<(Vec<ShareEntry>, Option<PublicLinkInfo>)> {
         let mut entries = Vec::new();
         for m in self
             .rt
-            .block_on(self.client.list_share_members(&uid))
+            .block_on(self.client.list_share_members(uid))
             .map_err(|e| CoreError::from_api(&e, "list members"))?
         {
             entries.push(ShareEntry {
@@ -87,7 +124,7 @@ impl Core {
         }
         for inv in self
             .rt
-            .block_on(self.client.list_share_invitations(&uid))
+            .block_on(self.client.list_share_invitations(uid))
             .map_err(|e| CoreError::from_api(&e, "list invitations"))?
         {
             entries.push(ShareEntry {
@@ -99,7 +136,7 @@ impl Core {
         }
         for ext in self
             .rt
-            .block_on(self.client.list_external_invitations(&uid))
+            .block_on(self.client.list_external_invitations(uid))
             .map_err(|e| CoreError::from_api(&e, "list external invitations"))?
         {
             entries.push(ShareEntry {
@@ -112,7 +149,7 @@ impl Core {
 
         let link = self
             .rt
-            .block_on(self.client.get_public_link(&uid))
+            .block_on(self.client.get_public_link(uid))
             .map_err(|e| CoreError::from_api(&e, "get public link"))?
             .map(public_link_info);
 
@@ -129,12 +166,35 @@ impl Core {
         role: &str,
     ) -> CoreResult<()> {
         let (_ino, uid) = self.resolve(rel)?;
+        self.update_share_role_for_uid(&uid, id, kind, role)
+    }
+
+    /// [`Core::update_share_role`] for a node addressed through any daemon
+    /// location.
+    pub(crate) fn update_share_role_by_uid(
+        &self,
+        uid: &str,
+        id: &str,
+        kind: ShareEntryKind,
+        role: &str,
+    ) -> CoreResult<()> {
+        let uid = self.resolve_anywhere(uid)?;
+        self.update_share_role_for_uid(&uid, id, kind, role)
+    }
+
+    fn update_share_role_for_uid(
+        &self,
+        uid: &NodeUid,
+        id: &str,
+        kind: ShareEntryKind,
+        role: &str,
+    ) -> CoreResult<()> {
         let role = role_from_str(role)?;
         match kind {
             ShareEntryKind::Member => {
                 let member = self
                     .rt
-                    .block_on(self.client.list_share_members(&uid))
+                    .block_on(self.client.list_share_members(uid))
                     .map_err(|e| CoreError::from_api(&e, "list members"))?
                     .into_iter()
                     .find(|m| m.membership_id.to_string() == id)
@@ -146,7 +206,7 @@ impl Core {
             ShareEntryKind::ProtonInvite => {
                 let inv = self
                     .rt
-                    .block_on(self.client.list_share_invitations(&uid))
+                    .block_on(self.client.list_share_invitations(uid))
                     .map_err(|e| CoreError::from_api(&e, "list invitations"))?
                     .into_iter()
                     .find(|i| i.invitation_id == id)
@@ -170,11 +230,32 @@ impl Core {
         kind: ShareEntryKind,
     ) -> CoreResult<()> {
         let (_ino, uid) = self.resolve(rel)?;
+        self.remove_share_entry_for_uid(&uid, id, kind)
+    }
+
+    /// [`Core::remove_share_entry`] for a node addressed through any daemon
+    /// location.
+    pub(crate) fn remove_share_entry_by_uid(
+        &self,
+        uid: &str,
+        id: &str,
+        kind: ShareEntryKind,
+    ) -> CoreResult<()> {
+        let uid = self.resolve_anywhere(uid)?;
+        self.remove_share_entry_for_uid(&uid, id, kind)
+    }
+
+    fn remove_share_entry_for_uid(
+        &self,
+        uid: &NodeUid,
+        id: &str,
+        kind: ShareEntryKind,
+    ) -> CoreResult<()> {
         match kind {
             ShareEntryKind::Member => {
                 let member = self
                     .rt
-                    .block_on(self.client.list_share_members(&uid))
+                    .block_on(self.client.list_share_members(uid))
                     .map_err(|e| CoreError::from_api(&e, "list members"))?
                     .into_iter()
                     .find(|m| m.membership_id.to_string() == id)
@@ -186,7 +267,7 @@ impl Core {
             ShareEntryKind::ProtonInvite => {
                 let inv = self
                     .rt
-                    .block_on(self.client.list_share_invitations(&uid))
+                    .block_on(self.client.list_share_invitations(uid))
                     .map_err(|e| CoreError::from_api(&e, "list invitations"))?
                     .into_iter()
                     .find(|i| i.invitation_id == id)
@@ -198,7 +279,7 @@ impl Core {
             ShareEntryKind::ExternalInvite => {
                 let ext = self
                     .rt
-                    .block_on(self.client.list_external_invitations(&uid))
+                    .block_on(self.client.list_external_invitations(uid))
                     .map_err(|e| CoreError::from_api(&e, "list external invitations"))?
                     .into_iter()
                     .find(|i| i.invitation_id == id)
@@ -219,13 +300,33 @@ impl Core {
         expires: Option<i64>,
     ) -> CoreResult<PublicLinkInfo> {
         let (_ino, uid) = self.resolve(rel)?;
+        self.create_public_link_for_uid(&uid, role, password, expires)
+    }
+
+    /// [`Core::create_public_link`] for a node addressed through any daemon
+    /// location.
+    pub(crate) fn create_public_link_by_uid(
+        &self,
+        uid: &str,
+        role: &str,
+        password: Option<&str>,
+        expires: Option<i64>,
+    ) -> CoreResult<PublicLinkInfo> {
+        let uid = self.resolve_anywhere(uid)?;
+        self.create_public_link_for_uid(&uid, role, password, expires)
+    }
+
+    fn create_public_link_for_uid(
+        &self,
+        uid: &NodeUid,
+        role: &str,
+        password: Option<&str>,
+        expires: Option<i64>,
+    ) -> CoreResult<PublicLinkInfo> {
         let role = role_from_str(role)?;
         let link = self
             .rt
-            .block_on(
-                self.client
-                    .create_public_link(&uid, role, password, expires),
-            )
+            .block_on(self.client.create_public_link(uid, role, password, expires))
             .map_err(|e| CoreError::from_api(&e, "create public link"))?;
         Ok(public_link_info(link))
     }
@@ -233,9 +334,20 @@ impl Core {
     /// 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)?;
+        self.remove_public_link_for_uid(&uid, id)
+    }
+
+    /// [`Core::remove_public_link`] for a node addressed through any daemon
+    /// location.
+    pub(crate) fn remove_public_link_by_uid(&self, uid: &str, id: &str) -> CoreResult<()> {
+        let uid = self.resolve_anywhere(uid)?;
+        self.remove_public_link_for_uid(&uid, id)
+    }
+
+    fn remove_public_link_for_uid(&self, uid: &NodeUid, id: &str) -> CoreResult<()> {
         let link = self
             .rt
-            .block_on(self.client.get_public_link(&uid))
+            .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"))?;

crates/pdfs-fuse/src/sweep.rs

@@ -82,7 +82,11 @@ impl Core {
                 return;
             }
         };
-        let nodes: Vec<_> = stored.into_iter().map(|s| s.node).collect();
+        let nodes: Vec<_> = stored
+            .into_iter()
+            .map(|stored| stored.node)
+            .filter(|node| self.is_own_or_virtual(&node.uid))
+            .collect();
 
         // Index live (non-trashed) files by (parent, name) for sibling lookup.
         let mut by_parent_name: HashMap<(String, &str), &_> = HashMap::new();
@@ -160,7 +164,10 @@ impl Core {
         self.for_each_state(|st| {
             st.forget_or_unlink(uid);
         });
-        self.discard_queued_ops(uid);
+        if let Err(error) = self.discard_queued_ops(uid) {
+            warn!(%uid, ?error, "conflict sweep: queued-op cleanup failed");
+            return;
+        }
         self.cache.evict(uid);
         self.evict_reader(uid);
         if let Err(e) = self.db.delete_node(uid) {
@@ -346,6 +353,7 @@ mod tests {
             is_shared: false,
             is_shared_publicly: false,
             signature_email: None,
+            membership: None,
             verification: Default::default(),
         }
     }

crates/pdfs-fuse/src/upload.rs

@@ -63,6 +63,12 @@ async fn run_uploads(
                 .transfers
                 .begin(&t.name, "", TransferDirection::Upload, t.size);
             let reader = OwnedCountingReader::new(file, guard);
+            if let Err(error) = core.require_uid_writable(&t.parent_uid) {
+                return Err((
+                    t.name,
+                    format!("destination access denied: errno {}", error.code()),
+                ));
+            }
             match core
                 .client
                 .upload_file_from(
@@ -110,6 +116,8 @@ impl Core {
         let (pino, parent_uid) = self.resolve(parent_rel)?;
         self.ensure_children(pino)
             .map_err(|e| self.errno_error(e, "enumerate"))?;
+        self.require_uid_writable(&parent_uid)
+            .map_err(|error| self.errno_error(error, "upload destination"))?;
 
         // Phase 1 (sequential): build the remote folder skeleton and collect the
         // flat list of files to upload. Folders must exist before their children,
@@ -170,6 +178,8 @@ impl Core {
                             {
                                 kids.push(ino);
                             }
+                            drop(st);
+                            self.flush_access_changes();
                         }
                         // Uploaded fine but the metadata refresh failed; it will
                         // appear on the next directory enumeration regardless.
@@ -205,19 +215,24 @@ impl Core {
         }
         self.ensure_children(pino)
             .map_err(|e| self.errno_error(e, "enumerate"))?;
-        {
+        let existing = {
             let st = self.state.lock();
-            if let Some(kids) = st.children.get(&pino) {
-                for &ino in kids {
-                    if let Some(e) = st.entries.get(&ino)
-                        && e.node.is_folder()
-                        && e.node.name == name
-                    {
-                        return Ok((ino, e.uid.clone()));
-                    }
-                }
-            }
+            st.children.get(&pino).and_then(|kids| {
+                kids.iter().find_map(|ino| {
+                    st.entries
+                        .get(ino)
+                        .filter(|entry| entry.node.is_folder() && entry.node.name == name)
+                        .map(|entry| (*ino, entry.uid.clone()))
+                })
+            })
+        };
+        if let Some((ino, uid)) = existing {
+            self.require_uid_writable(&uid)
+                .map_err(|error| self.errno_error(error, "upload destination"))?;
+            return Ok((ino, uid));
         }
+        self.require_uid_writable(parent_uid)
+            .map_err(|error| self.errno_error(error, "upload destination"))?;
         let new_uid = self
             .rt
             .block_on(
@@ -235,6 +250,10 @@ impl Core {
         {
             kids.push(ino);
         }
+        drop(st);
+        self.flush_access_changes();
+        self.require_uid_writable(&new_uid)
+            .map_err(|error| self.errno_error(error, "created upload destination"))?;
         Ok((ino, new_uid))
     }
 

crates/pdfs-fuse/src/virtual.rs

@@ -0,0 +1,318 @@
+//! Synthetic nodes and naming rules for the mounted shared tree.
+
+use std::collections::{HashMap, HashSet};
+use std::time::{Duration, Instant};
+
+use proton_drive_rs::proton_sdk::ids::{LinkId, NodeUid, VolumeId};
+use proton_drive_rs::{Node, NodeKind};
+
+pub(crate) const VIRTUAL_VOLUME: &str = "virtual";
+pub(crate) const SHARED_WITH_ME_LINK: &str = "sharedwithme";
+pub(crate) const SHARED_WITH_ME_BASE: &str = "Shared with me";
+const MAX_COMPONENT_BYTES: usize = 255;
+
+pub(crate) fn shared_with_me_uid() -> NodeUid {
+    NodeUid::new(
+        VolumeId::from(VIRTUAL_VOLUME),
+        LinkId::from(SHARED_WITH_ME_LINK),
+    )
+}
+
+pub(crate) fn is_virtual_uid(uid: &NodeUid) -> bool {
+    uid.volume_id.as_str() == VIRTUAL_VOLUME
+}
+
+pub(crate) fn is_own_or_virtual_uid(uid: &NodeUid, own_volume: &VolumeId) -> bool {
+    uid.volume_id == *own_volume || is_virtual_uid(uid)
+}
+
+pub(crate) fn is_primary_root_listing(
+    primary: bool,
+    folder_uid: &NodeUid,
+    primary_root_uid: &NodeUid,
+) -> bool {
+    primary && folder_uid == primary_root_uid
+}
+
+pub(crate) fn virtual_node(parent_uid: NodeUid, name: String, timestamp: i64) -> Node {
+    Node {
+        uid: shared_with_me_uid(),
+        parent_uid: Some(parent_uid),
+        name,
+        kind: NodeKind::Folder,
+        creation_time: timestamp,
+        modification_time: timestamp,
+        trashed: false,
+        is_shared: false,
+        is_shared_publicly: false,
+        signature_email: None,
+        membership: None,
+        verification: Default::default(),
+    }
+}
+
+/// Choose the initial synthetic-root name. Once persisted, `pinned` always wins;
+/// a later real collision only controls whether the synthetic dentry is exposed.
+pub(crate) fn virtual_root_name(
+    real_names: &HashSet<String>,
+    pinned: Option<&str>,
+) -> (String, bool) {
+    if let Some(pinned) = pinned {
+        return (pinned.to_string(), !real_names.contains(pinned));
+    }
+    for n in 0usize.. {
+        let candidate = match n {
+            0 => SHARED_WITH_ME_BASE.to_string(),
+            1 => format!("{SHARED_WITH_ME_BASE} (Proton)"),
+            _ => format!("{SHARED_WITH_ME_BASE} (Proton {n})"),
+        };
+        if !real_names.contains(&candidate) {
+            return (candidate, true);
+        }
+    }
+    unreachable!("the numbered virtual-root namespace is unbounded")
+}
+
+/// Give every shared root a unique Linux component name, independent of API
+/// ordering. Literal suffix-shaped names reserve their basename before duplicate
+/// names are numbered, so `Photos (2)` is never stolen by a second `Photos`.
+pub(crate) fn disambiguate_shared_names(nodes: &mut [Node]) {
+    nodes.sort_by(|a, b| {
+        a.name
+            .cmp(&b.name)
+            .then_with(|| a.uid.to_string().cmp(&b.uid.to_string()))
+    });
+    let reserved: HashSet<String> = nodes
+        .iter()
+        .map(|node| component_with_suffix(&node.name, ""))
+        .collect();
+    let mut used = HashSet::with_capacity(nodes.len());
+
+    for node in nodes {
+        let original = node.name.clone();
+        let basename = component_with_suffix(&original, "");
+        let chosen = if used.insert(basename.clone()) {
+            basename
+        } else {
+            let mut n = 2usize;
+            loop {
+                let suffix = format!(" ({n})");
+                let candidate = component_with_suffix(&original, &suffix);
+                if !reserved.contains(&candidate) && used.insert(candidate.clone()) {
+                    break candidate;
+                }
+                n += 1;
+            }
+        };
+        node.name = chosen;
+    }
+}
+
+pub(crate) fn listing_needs_refresh(online: bool, stale: bool) -> bool {
+    online && stale
+}
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+pub(crate) enum SharedListingPlan {
+    Resident,
+    Persisted,
+    Refresh,
+}
+
+pub(crate) fn shared_listing_plan(resident: bool, online: bool, stale: bool) -> SharedListingPlan {
+    if listing_needs_refresh(online, stale) {
+        SharedListingPlan::Refresh
+    } else if resident {
+        SharedListingPlan::Resident
+    } else {
+        SharedListingPlan::Persisted
+    }
+}
+
+pub(crate) fn refresh_generation_is_current(started: u64, current: u64) -> bool {
+    started == current
+}
+
+#[derive(Default)]
+pub(crate) struct SharedRefreshDeadlines {
+    deadlines: HashMap<String, Instant>,
+}
+
+impl SharedRefreshDeadlines {
+    pub(crate) fn is_fresh(&mut self, key: &str, now: Instant) -> bool {
+        self.deadlines.retain(|_, deadline| *deadline > now);
+        self.deadlines
+            .get(key)
+            .is_some_and(|deadline| *deadline > now)
+    }
+
+    pub(crate) fn mark(&mut self, key: &str, now: Instant, ttl: Duration) {
+        self.deadlines.insert(key.to_string(), now + ttl);
+    }
+
+    pub(crate) fn clear(&mut self) {
+        self.deadlines.clear();
+    }
+}
+
+fn component_with_suffix(name: &str, suffix: &str) -> String {
+    let keep = MAX_COMPONENT_BYTES.saturating_sub(suffix.len());
+    let mut boundary = name.len().min(keep);
+    while !name.is_char_boundary(boundary) {
+        boundary -= 1;
+    }
+    let mut out = String::with_capacity(boundary + suffix.len());
+    out.push_str(&name[..boundary]);
+    out.push_str(suffix);
+    out
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    fn folder(volume: &str, link: &str, name: &str) -> Node {
+        let mut node = virtual_node(
+            NodeUid::new(VolumeId::from("virtual"), LinkId::from("parent")),
+            name.to_string(),
+            1,
+        );
+        node.uid = NodeUid::new(VolumeId::from(volume), LinkId::from(link));
+        node
+    }
+
+    #[test]
+    fn virtual_uid_and_node_round_trip() {
+        let parent = NodeUid::new(VolumeId::from("own"), LinkId::from("root"));
+        let node = virtual_node(parent.clone(), SHARED_WITH_ME_BASE.into(), 42);
+        assert_eq!(node.uid.to_string(), "virtual~sharedwithme");
+        assert!(is_virtual_uid(&node.uid));
+        assert_eq!(node.parent_uid.as_ref(), Some(&parent));
+        assert!(node.is_folder());
+        let json = serde_json::to_string(&node).unwrap();
+        let restored: Node = serde_json::from_str(&json).unwrap();
+        assert_eq!(restored.uid, node.uid);
+        assert_eq!(restored.name, SHARED_WITH_ME_BASE);
+    }
+
+    #[test]
+    fn root_collision_ladder_and_pinned_collision_policy() {
+        let names = HashSet::from([
+            SHARED_WITH_ME_BASE.to_string(),
+            format!("{SHARED_WITH_ME_BASE} (Proton)"),
+            format!("{SHARED_WITH_ME_BASE} (Proton 2)"),
+        ]);
+        assert_eq!(
+            virtual_root_name(&names, None),
+            (format!("{SHARED_WITH_ME_BASE} (Proton 3)"), true)
+        );
+
+        let (name, visible) = virtual_root_name(&names, Some(SHARED_WITH_ME_BASE));
+        assert_eq!(name, SHARED_WITH_ME_BASE);
+        assert!(!visible, "a real later collision suppresses the dentry");
+
+        let cleared = HashSet::new();
+        assert_eq!(
+            virtual_root_name(&cleared, Some(SHARED_WITH_ME_BASE)),
+            (SHARED_WITH_ME_BASE.to_string(), true),
+            "the pinned name returns when the collision clears"
+        );
+    }
+
+    #[test]
+    fn duplicate_names_are_stable_under_reordering_and_reserve_suffixes() {
+        let input = vec![
+            folder("b", "2", "Photos"),
+            folder("c", "3", "Photos (2)"),
+            folder("a", "1", "Photos"),
+        ];
+        let mut forward = input.clone();
+        let mut reverse = input;
+        reverse.reverse();
+        disambiguate_shared_names(&mut forward);
+        disambiguate_shared_names(&mut reverse);
+        let summarize = |nodes: &[Node]| {
+            nodes
+                .iter()
+                .map(|node| (node.uid.to_string(), node.name.clone()))
+                .collect::<Vec<_>>()
+        };
+        assert_eq!(summarize(&forward), summarize(&reverse));
+        assert_eq!(
+            forward
+                .iter()
+                .map(|node| node.name.as_str())
+                .collect::<Vec<_>>(),
+            ["Photos", "Photos (3)", "Photos (2)"]
+        );
+    }
+
+    #[test]
+    fn disambiguation_respects_utf8_component_limit() {
+        let long = "é".repeat(200);
+        let mut nodes = vec![folder("a", "1", &long), folder("b", "2", &long)];
+        disambiguate_shared_names(&mut nodes);
+        assert!(nodes.iter().all(|node| node.name.len() <= 255));
+        assert!(
+            nodes
+                .iter()
+                .all(|node| node.name.is_char_boundary(node.name.len()))
+        );
+        assert_ne!(nodes[0].name, nodes[1].name);
+        assert!(nodes[1].name.ends_with(" (2)"));
+    }
+
+    #[test]
+    fn ttl_refresh_only_happens_online() {
+        assert!(!listing_needs_refresh(false, true));
+        assert!(!listing_needs_refresh(true, false));
+        assert!(listing_needs_refresh(true, true));
+    }
+
+    #[test]
+    fn offline_snapshot_suppresses_the_api_and_memory_deadline_suppresses_retries() {
+        assert_eq!(
+            shared_listing_plan(false, false, true),
+            SharedListingPlan::Persisted
+        );
+        assert_eq!(
+            shared_listing_plan(true, true, false),
+            SharedListingPlan::Resident
+        );
+
+        let now = Instant::now();
+        let mut deadlines = SharedRefreshDeadlines::default();
+        deadlines.mark("shared", now, Duration::from_secs(60));
+        assert!(deadlines.is_fresh("shared", now + Duration::from_secs(30)));
+        deadlines.clear();
+        assert!(!deadlines.is_fresh("shared", now + Duration::from_secs(30)));
+    }
+
+    #[test]
+    fn generation_change_rejects_an_inflight_response() {
+        assert!(refresh_generation_is_current(7, 7));
+        assert!(!refresh_generation_is_current(7, 8));
+    }
+
+    #[test]
+    fn only_the_primary_inode_space_installs_the_synthetic_root() {
+        let root = NodeUid::new(VolumeId::from("own"), LinkId::from("root"));
+        assert!(is_primary_root_listing(true, &root, &root));
+        assert!(!is_primary_root_listing(false, &root, &root));
+        assert!(!is_primary_root_listing(
+            true,
+            &NodeUid::new(VolumeId::from("own"), LinkId::from("device")),
+            &root
+        ));
+    }
+
+    #[test]
+    fn ownership_predicate_excludes_foreign_share_volumes() {
+        let own = VolumeId::from("own");
+        let own_uid = NodeUid::new(own.clone(), LinkId::from("file"));
+        let foreign = NodeUid::new(VolumeId::from("foreign"), LinkId::from("share"));
+        assert!(is_own_or_virtual_uid(&own_uid, &own));
+        assert!(is_own_or_virtual_uid(&shared_with_me_uid(), &own));
+        assert!(!is_own_or_virtual_uid(&foreign, &own));
+    }
+}

docs/BUGS.md

@@ -1432,12 +1432,22 @@ added later, but it must retain the row and blob.
 
 ## B34 — Writable POSIX Exposure of Read-Only Shared Folders (MED-07)
 
-**Status:** Open  
+**Status:** Fixed in code by P2/P3 (2026-07-29); P3 now exposes the shared tree, while credentialed
+second-account and live FUSE acceptance remain pending P7
 **Found:** 2026-07-21, multi-agent permissions audit (`audit_bugs.md` MED-07)  
 **Where:** `crates/pdfs-fuse/src/lib.rs`, `crates/pdfs-fuse/src/sharing.rs`
 
 **Cause:** Shared "Viewer" (read-only) folders are exposed via POSIX with write permissions (`0755`). Local writes succeed initially on the mount but fail perpetually during background online drain with `403 Forbidden` errors.
 
+**Fix:** P2 persists share authority in schema V17 `share_access`, inherits it through resident
+entries, exposes read-only POSIX modes, and gates mutations at handler, queue, and drain boundaries.
+Downgrades fail closed and are not acknowledged past failed durable state updates.
+
+**Verification:** The local workspace passes formatting, locked checks, clippy with warnings denied,
+and all 347 workspace tests, including P3 virtual-tree materialization and access inheritance plus
+mutation gating, queued-operation authorization, and downgrade failure paths. Credentialed
+second-account and live FUSE acceptance have not been run and remain required in P7.
+
 ---
 
 ## B35 — IPC Unix Socket Creation Permission Race (MED-08)
@@ -2356,12 +2366,48 @@ correct behaviour for the first live pass is to trash nothing.
 
 ## B72 — `pdfs trash` never returns
 
-**Status:** Open — found 2026-07-26.
+**Status:** Hardened in-tree 2026-07-26 — the hang is gone by construction; the
+underlying slowness of the first refresh is still unmeasured (live-pending).
 **Found:** capturing a trash baseline before the B69/B70 live validation. `pdfs trash`
 produced no output and was still running when killed at 120 s. Daemon was healthy
 and every other CLI call (`pdfs sync list`, `pdfs --version`) returned promptly.
-**Where:** unconfirmed — either the `Request` handler in `crates/pdfs-fuse/src/control.rs`
-or the CLI's response read in `crates/pdfs-cli/src/main.rs`.
+**Where:** `Core::list_trash` (`crates/pdfs-fuse/src/lib.rs`). Not the CLI: the
+client's 120 s `READ_TIMEOUT` (`pdfs-core/src/control.rs`) is what ends the call,
+and the daemon never writes a response line.
+
+**Root cause.** The trash of this account had never been fetched successfully —
+`trash` table empty, no `trash_synced_ms` in `sync_state`. `list_trash` therefore
+always took its "never fetched → `rt.block_on(refresh_trash())`" branch, which:
+
+- materialized the *entire* trash in one `enumerate_nodes` call (one S2K unlock
+  per node) before persisting anything, so nothing was ever saved and no later
+  request could be served from the DB;
+- had no single-flight guard on that branch (only `spawn_trash_refresh` did), so
+  every attempt started another full refresh;
+- was never cancelled when the requester timed out, because the control handler
+  sits in `block_on` on its own thread and nothing signals it.
+
+So each look at the trash added a permanent, full-cost refresh to the daemon.
+Measured on the live daemon after a handful of GUI/CLI attempts: **11 stale
+`pdfs-control` threads**, RSS 2.9 GB. Concurrent with a drain backlog that was
+uploading conflict copies continuously (1991 `Conflict` activity rows, multi-GB
+uploads), none of the refreshes ever finished.
+
+**Fix (in-tree).** `list_trash` never blocks on the whole refresh: it kicks the
+single-flighted background refresh, waits at most `TRASH_FIRST_WAIT` (20 s, well
+under the front-end read timeout) on a `Notify`, and answers with whatever has
+materialized. `refresh_trash` now materializes in `TRASH_MATERIALIZE_CHUNK` (150)
+batches, persisting the cumulative listing after each one, and logs the uid count
+plus per-batch and total elapsed at INFO/DEBUG — previously the whole path was
+silent, which is why the stall could not be located from the journal.
+
+**Still open:** *why* one refresh is slow enough to matter. The new INFO lines
+(`trash refresh: enumerated` / `batch` / `done`) answer that on the next run:
+whether `enumerate_trash_node_uids` returns at all, how many nodes the trash
+holds, and the per-batch cost. If the count is large, materializing with
+`enumerate_nodes_light` (skips the per-file node-key S2K; `size` would fall back
+to on-storage size) is the next lever.
+
 **Impact:** the trash listing is the user's recovery path after any destructive
 operation, including the B71 sweep. It needs to work before the sweep is allowed
 to trash anything.

packaging/PKGBUILD

@@ -9,7 +9,7 @@
 # Build + install:   cd packaging && makepkg -fi
 
 pkgname=proton-drive-linux
-pkgver=1.1.0
+pkgver=1.2.0
 pkgrel=1
 pkgdesc="Proton Drive client for Linux: FUSE files-on-demand mount, CLI, GTK4 app + tray"
 arch=('x86_64')