Merge pull request #41 from narrrl/release/3.5.0

Release/3.5.0

.github/workflows/ci.yml

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

Cargo.lock

@@ -3474,7 +3474,7 @@ checksum = "2ee67f1008b1ba2321834326597b8e186293b049a023cdef258527550b9935b4"
 
 [[package]]
 name = "pdfs-cli"
-version = "3.4.1"
+version = "3.5.0"
 dependencies = [
  "anyhow",
  "clap",
@@ -3490,13 +3490,14 @@ dependencies = [
 
 [[package]]
 name = "pdfs-core"
-version = "3.4.1"
+version = "3.5.0"
 dependencies = [
  "async-trait",
  "base64 0.23.1",
  "dbus-secret-service-keyring-store",
  "directories",
  "ignore",
+ "kamadak-exif",
  "keyring-core",
  "libc",
  "parking_lot",
@@ -3516,7 +3517,7 @@ dependencies = [
 
 [[package]]
 name = "pdfs-fuse"
-version = "3.4.1"
+version = "3.5.0"
 dependencies = [
  "async-trait",
  "base64 0.23.1",
@@ -3538,7 +3539,7 @@ dependencies = [
 
 [[package]]
 name = "pdfs-gui"
-version = "3.4.1"
+version = "3.5.0"
 dependencies = [
  "anyhow",
  "async-channel",

Cargo.toml

@@ -3,7 +3,7 @@ resolver = "2"
 members = ["crates/pdfs-core", "crates/pdfs-fuse", "crates/pdfs-cli", "crates/pdfs-gui"]
 
 [workspace.package]
-version = "3.4.1"
+version = "3.5.0"
 edition = "2024"
 license = "MIT"
 authors = ["Nils Pukropp <contact@narl.io>"]
@@ -61,3 +61,15 @@ async-trait = "0.1"
 futures = "0.3"
 fuser = "0.18"
 libc = "0.2"
+
+[profile.release]
+# No package ships a separate debug package (the PKGBUILD sets `!debug`, the
+# RPM spec sets `debug_package` to nil), and the unstripped binaries weighed
+# 43 MB (`pdfs`), 24 MB (`pdfs-app`) and 12 MB (`pdfs-tray`).
+strip = "symbols"
+# Off on purpose: LTO has broken GTK links for this workspace, which is why
+# the packages turn it off as well.
+lto = false
+# `Workers` and the thumbnail build catch panics to keep the daemon alive, so
+# unwinding must stay on.
+panic = "unwind"

crates/pdfs-cli/src/main.rs

@@ -630,6 +630,16 @@ enum DeviceCmd {
         #[arg(long, conflicts_with = "uid")]
         clear: bool,
     },
+    /// Sync the same folders as another computer: this machine continues that
+    /// computer's device alongside it, and its folders are offered for syncing
+    /// here. Both computers keep them in step.
+    Join {
+        /// Device uid (from `devices list`).
+        uid: String,
+        /// Skip the confirmation and accept every proposed local path.
+        #[arg(long)]
+        yes: bool,
+    },
     /// Move another computer's folders into this computer's backup and sync
     /// them here. The other computer stays registered, without those folders.
     Migrate {
@@ -831,6 +841,20 @@ fn main() -> Result<()> {
 
     let cli = Cli::parse();
     JSON_OUTPUT.store(cli.json, std::sync::atomic::Ordering::Relaxed);
+    // The commands that hold the password, the key passphrases or the session
+    // tokens in memory: keep them out of core dumps and away from same-user
+    // ptrace. Only the daemon did, though `mount` holds the same keys for as
+    // long as it runs.
+    if matches!(
+        cli.command,
+        Command::Login { .. }
+            | Command::Unlock { .. }
+            | Command::Logout
+            | Command::Mount { .. }
+            | Command::Daemon { .. }
+    ) {
+        pdfs_core::kernelkey::forbid_dumps();
+    }
     match cli.command {
         Command::Login { username, remember } => cmd_login(username, remember),
         Command::Unlock { remember } => cmd_unlock(remember),
@@ -978,6 +1002,26 @@ fn cmd_devices(action: DeviceCmd) -> Result<()> {
             let uid = if clear { None } else { uid };
             ok_or_bail(control_request(CtlRequest::AdoptDevice { uid })?)?
         }
+        DeviceCmd::Join { uid, yes } => {
+            if !yes {
+                println!(
+                    "This computer syncs into that device alongside it. Its folders are kept\n\
+                     in step on both computers: an edit or a deletion on one reaches the other.\n\
+                     New synced folders here go under that device too. Folders already synced\n\
+                     here stay where they are."
+                );
+                confirm("Sync with it?")?;
+            }
+            let response = control_request(CtlRequest::AdoptDevice { uid: Some(uid) })?;
+            // A script gets the one reply and runs `sync restore` itself.
+            if emit_json(&response)? {
+                return Ok(());
+            }
+            ok_or_bail(response)?;
+            // The device is this machine's now, so the plain restore offers its
+            // folders.
+            cmd_sync_restore(yes, None)?
+        }
         DeviceCmd::Migrate { uid, yes } => {
             if !yes {
                 println!(
@@ -1977,8 +2021,14 @@ fn key_state_name() -> &'static str {
 }
 
 fn cmd_logout() -> Result<()> {
-    auth::logout()?;
-    println!("Stored session cleared.");
+    if auth::logout()? {
+        println!("Signed out: the session is ended on Proton and cleared here.");
+    } else {
+        println!(
+            "Stored session cleared. Proton could not be reached to end the session; \
+             it stays valid until it expires or is signed out in your account's security settings."
+        );
+    }
     Ok(())
 }
 
@@ -2221,9 +2271,6 @@ where
 /// an external unmount triggers a remount; errors back off and retry. This is
 /// the entry point for the systemd user service.
 fn cmd_daemon(mountpoint: Option<PathBuf>) -> Result<()> {
-    // The daemon holds the account's key passphrases in memory; keep them out
-    // of core dumps and away from same-user ptrace.
-    pdfs_core::kernelkey::forbid_dumps();
     loop {
         // Wait until a session is stored. The GUI enables this service on login,
         // but the service may also start at boot before the user has logged in.
@@ -2592,7 +2639,10 @@ fn cmd_import_google_photos(archives: Vec<PathBuf>, dry_run: bool, wait: bool) -
             } => continue,
             CtlResponse::ImportStatus { summary, .. } => {
                 print_import_summary(summary.as_ref());
-                return Ok(());
+                return finished_run(
+                    "the import",
+                    summary.map(|s| (s.failed, s.cancelled, s.error)),
+                );
             }
             CtlResponse::Error { message, kind } => bail!("{}", cli_error(kind, &message)),
             other => bail!("unexpected response: {other:?}"),
@@ -2635,7 +2685,10 @@ fn cmd_redate_photos(
             CtlResponse::RedateStatus { running: true, .. } => continue,
             CtlResponse::RedateStatus { summary, .. } => {
                 print_redate_summary(summary.as_ref());
-                return Ok(());
+                return finished_run(
+                    "the re-date",
+                    summary.map(|s| (s.failed, s.cancelled, s.error)),
+                );
             }
             CtlResponse::Error { message, kind } => bail!("{}", cli_error(kind, &message)),
             other => bail!("unexpected response: {other:?}"),
@@ -2643,6 +2696,22 @@ fn cmd_redate_photos(
     }
 }
 
+/// How a run `--wait` followed ended, as the exit status: an error when it
+/// failed, was cancelled, or left photos failed, so a script can tell.
+/// `outcome` is `(failed, cancelled, error)`; `None` when the daemon has no
+/// result, which happens when it restarted during the run.
+fn finished_run(what: &str, outcome: Option<(usize, bool, Option<String>)>) -> Result<()> {
+    match outcome {
+        None => bail!("{what} ended without a result; the service may have restarted"),
+        Some((_, _, Some(error))) => bail!("{what} failed: {error}"),
+        Some((_, true, None)) => bail!("{what} was cancelled"),
+        Some((failed, false, None)) if failed > 0 => {
+            bail!("{what} finished, but {failed} photo(s) failed")
+        }
+        Some(_) => Ok(()),
+    }
+}
+
 /// A `YYYY-MM-DD` day as epoch seconds at UTC midnight. Reuses the Takeout
 /// scanner's date reader, which already accepts exactly this spelling.
 fn parse_day(day: &str) -> Result<i64> {
@@ -2678,6 +2747,10 @@ fn print_redate_summary(summary: Option<&pdfs_core::control::RedateSummary>) {
         println!("No re-date has run yet.");
         return;
     };
+    if let Some(error) = &summary.error {
+        println!("Failed           : {error}");
+        return;
+    }
     println!("Photos examined  : {}", summary.examined);
     println!("Mis-dated        : {}", summary.candidates);
     if summary.dry_run {
@@ -2737,6 +2810,10 @@ fn print_import_summary(summary: Option<&pdfs_core::control::ImportSummary>) {
         println!("No import has run yet.");
         return;
     };
+    if let Some(error) = &summary.error {
+        println!("Failed           : {error}");
+        return;
+    }
     println!("Photos in export : {}", summary.found);
     println!("Uploaded         : {}", summary.uploaded);
     println!("Already on Proton: {}", summary.duplicates);
@@ -3751,6 +3828,28 @@ mod login_wait_tests {
         assert_eq!(login_poll_delay(u32::MAX), Duration::from_secs(15));
     }
 
+    /// The file-manager script passes each selected path after `--`, so a
+    /// file named like an option is still the path.
+    #[test]
+    fn a_path_after_a_double_dash_is_a_path_even_when_it_looks_like_a_flag() {
+        let cli = Cli::try_parse_from(["pdfs", "pin", "--", "--json"]).unwrap();
+        assert!(!cli.json);
+        match cli.command {
+            Command::Pin { path } => assert_eq!(path, PathBuf::from("--json")),
+            _ => panic!("not a pin"),
+        }
+    }
+
+    #[test]
+    fn a_waited_for_run_that_did_not_fully_succeed_exits_with_an_error() {
+        assert!(finished_run("the import", Some((0, false, None))).is_ok());
+        assert!(finished_run("the import", Some((3, false, None))).is_err());
+        assert!(finished_run("the import", Some((0, true, None))).is_err());
+        let failed = finished_run("the import", Some((0, false, Some("not a zip".into()))));
+        assert!(failed.unwrap_err().to_string().contains("not a zip"));
+        assert!(finished_run("the import", None).is_err());
+    }
+
     #[test]
     fn waiting_for_a_session_stops_hammering_the_keyring() {
         let mut checks_left = 20;

crates/pdfs-core/Cargo.toml

@@ -30,3 +30,4 @@ async-trait.workspace = true
 libc.workspace = true
 zeroize.workspace = true
 base64.workspace = true
+exif = { version = "0.6", package = "kamadak-exif" }

crates/pdfs-core/src/auth.rs

@@ -516,8 +516,59 @@ pub fn lock(forget: bool) -> Result<()> {
     Ok(())
 }
 
-/// Forget the persisted session (best-effort; absent entry is not an error).
-pub fn logout() -> Result<()> {
+/// How long [`logout`] waits for Proton to end the session before it signs
+/// out locally without.
+const END_SESSION_TIMEOUT: Duration = Duration::from_secs(10);
+
+/// End the stored session on Proton's side (`DELETE auth/v4`). Returns false
+/// when there is none or Proton could not be reached in time.
+///
+/// Runs on a thread of its own, so it works the same whether the caller is
+/// inside a tokio runtime or not.
+fn end_server_session() -> bool {
+    let Ok(stored) = load() else {
+        return false;
+    };
+    let ended = std::thread::scope(|scope| {
+        scope
+            .spawn(|| -> std::result::Result<(), String> {
+                let rt = tokio::runtime::Builder::new_current_thread()
+                    .enable_all()
+                    .build()
+                    .map_err(|e| e.to_string())?;
+                rt.block_on(async {
+                    let session = resume_stored(&stored).map_err(|e| e.to_string())?;
+                    match tokio::time::timeout(END_SESSION_TIMEOUT, session.end()).await {
+                        Ok(result) => result.map_err(|e| e.to_string()),
+                        Err(_) => Err(format!(
+                            "no answer within {}s",
+                            END_SESSION_TIMEOUT.as_secs()
+                        )),
+                    }
+                })
+            })
+            .join()
+            .unwrap_or_else(|_| Err("the sign-out thread panicked".into()))
+    });
+    match ended {
+        Ok(()) => true,
+        Err(error) => {
+            tracing::warn!(%error, "ending the session on Proton failed; signing out locally");
+            false
+        }
+    }
+}
+
+/// End the session on Proton, then forget it here. Returns whether Proton
+/// ended it: offline, the session stays valid on Proton's side until it
+/// expires or is signed out from the account's security settings.
+///
+/// Before this, signing out only deleted the keyring entry. The tokens stayed
+/// valid on Proton, so a copy of them taken from this machine still worked.
+///
+/// The local half is best effort; an absent entry is not an error.
+pub fn logout() -> Result<bool> {
+    let ended = end_server_session();
     // The persisted entity cache describes the account being logged out of. It
     // is encrypted under a key derived from that account's passphrases, but
     // leaving it behind would also mean the next account inherits a store it can
@@ -539,7 +590,7 @@ pub fn logout() -> Result<()> {
     }
     let _ = kernelkey::UNSAVED_TOKENS.clear();
     match keyring_entry()?.delete_credential() {
-        Ok(()) | Err(keyring_core::Error::NoEntry) => Ok(()),
+        Ok(()) | Err(keyring_core::Error::NoEntry) => Ok(ended),
         Err(e) => Err(e.into()),
     }
 }

crates/pdfs-core/src/config.rs

@@ -163,6 +163,10 @@ pub struct AppConfig {
     /// Defaulted for configs predating the field.
     #[serde(default)]
     pub files_view: FilesView,
+    /// The desktop app's main window size, remembered between runs. Defaulted
+    /// for configs predating the field.
+    #[serde(default)]
+    pub window: WindowState,
     /// The user hid the tray icon from its own menu. The tray exits at start
     /// while this is set, and the app does not spawn it; Preferences turns it
     /// back on. Defaulted for configs predating the field.
@@ -211,6 +215,44 @@ impl Default for FilesView {
     }
 }
 
+/// The desktop app's main window, as it was when it last closed.
+#[derive(Serialize, Deserialize, Debug, Clone, Copy, PartialEq, Eq)]
+#[serde(default)]
+pub struct WindowState {
+    /// The unmaximised size, in logical pixels.
+    pub width: i32,
+    pub height: i32,
+    pub maximized: bool,
+}
+
+impl WindowState {
+    /// Below this the saved size is taken for damage and the default is used.
+    pub const MIN_WIDTH: i32 = 480;
+    pub const MIN_HEIGHT: i32 = 400;
+
+    /// This state, with a size too small to use replaced by the default.
+    pub fn usable(self) -> Self {
+        if self.width < Self::MIN_WIDTH || self.height < Self::MIN_HEIGHT {
+            Self {
+                maximized: self.maximized,
+                ..Self::default()
+            }
+        } else {
+            self
+        }
+    }
+}
+
+impl Default for WindowState {
+    fn default() -> Self {
+        Self {
+            width: 980,
+            height: 680,
+            maximized: false,
+        }
+    }
+}
+
 /// The key a My Files listing is ordered by.
 #[derive(Serialize, Deserialize, Debug, Clone, Copy, PartialEq, Eq, Default)]
 #[serde(rename_all = "lowercase")]
@@ -310,6 +352,22 @@ impl AppConfig {
     }
 }
 
+/// Fail when the config file at `path` exists but does not parse, so that
+/// [`AppDirs::save_config`] never writes over settings it could not read.
+fn refuse_to_replace_unreadable(path: &Path) -> Result<()> {
+    match std::fs::read_to_string(path) {
+        Ok(content) => match serde_json::from_str::<AppConfig>(&content) {
+            Ok(_) => Ok(()),
+            Err(e) => Err(Error::Other(format!(
+                "{} cannot be read ({e}); fix it or move it aside before changing settings",
+                path.display()
+            ))),
+        },
+        Err(e) if e.kind() == std::io::ErrorKind::NotFound => Ok(()),
+        Err(e) => Err(e.into()),
+    }
+}
+
 /// Resolved XDG locations for state, cache, and the default mountpoint.
 pub struct AppDirs {
     dirs: ProjectDirs,
@@ -341,6 +399,7 @@ impl AppDirs {
                     // Preserve the original bytes for diagnosis/recovery.  In
                     // particular, never replace a truncated config with defaults
                     // and silently lose mount, device, or ignore settings.
+                    // `save_config` refuses to write over it for the same reason.
                     tracing::error!(path = %path.display(), error = %e, "config is unreadable; using in-memory defaults without overwriting it");
                     return AppConfig::default();
                 }
@@ -348,9 +407,8 @@ impl AppDirs {
         }
 
         let default_config = AppConfig::default();
-        if let Ok(content) = serde_json::to_string_pretty(&default_config) {
-            let _ = std::fs::create_dir_all(self.dirs.config_dir());
-            let _ = std::fs::write(&path, content);
+        if let Err(e) = self.save_config(&default_config) {
+            tracing::warn!(path = %path.display(), error = %e, "could not write the default config");
         }
         default_config
     }
@@ -358,8 +416,15 @@ impl AppDirs {
     /// Persist `config` to [`config_path`](Self::config_path), creating the
     /// config dir if missing. The Settings page calls this after editing the
     /// cache budget or mountpoint; the daemon re-reads the file on its next mount.
+    ///
+    /// Refuses while the file on disk does not parse. Every caller loads,
+    /// changes one field and saves, and [`load_config`](Self::load_config)
+    /// gives defaults for a file it cannot read, so the first change after
+    /// the file was damaged wrote defaults over the mountpoint, the device and
+    /// the ignore rules the user had (`docs/BUGS.md` B223).
     pub fn save_config(&self, config: &AppConfig) -> Result<()> {
         let path = self.config_path();
+        refuse_to_replace_unreadable(&path)?;
         let parent = path
             .parent()
             .ok_or_else(|| Error::Other("configuration path has no parent".into()))?;
@@ -383,6 +448,46 @@ impl AppDirs {
         Ok(())
     }
 
+    /// This machine's id (e.g. ~/.config/proton-drive-linux/machine-id). See
+    /// [`machine_id`](Self::machine_id).
+    pub fn machine_id_path(&self) -> PathBuf {
+        self.dirs.config_dir().join("machine-id")
+    }
+
+    /// A random id for this machine, made on first use and kept in
+    /// [`machine_id_path`](Self::machine_id_path).
+    ///
+    /// It names this machine's profile in a device it may share with other
+    /// computers. Random rather than `/etc/machine-id`, so nothing that
+    /// identifies the host goes to Drive. In a file of its own rather than
+    /// `config.json`, because the app saves the config from a copy it loaded
+    /// earlier, and that would drop an id the daemon had just added.
+    pub fn machine_id(&self) -> Result<String> {
+        let path = self.machine_id_path();
+        match std::fs::read_to_string(&path) {
+            Ok(id) if is_machine_id(id.trim()) => return Ok(id.trim().to_string()),
+            Ok(_) => {
+                tracing::warn!(path = %path.display(), "machine id is unusable; making a new one");
+            }
+            Err(e) if e.kind() == std::io::ErrorKind::NotFound => {}
+            Err(e) => return Err(e.into()),
+        }
+        let mut bytes = [0u8; 16];
+        use std::io::Read as _;
+        std::fs::File::open("/dev/urandom")?.read_exact(&mut bytes)?;
+        let id: String = bytes.iter().map(|b| format!("{b:02x}")).collect();
+        let parent = path
+            .parent()
+            .ok_or_else(|| Error::Other("machine id path has no parent".into()))?;
+        std::fs::create_dir_all(parent)?;
+        let tmp = path.with_extension(format!("tmp-{}", std::process::id()));
+        std::fs::write(&tmp, format!("{id}\n"))?;
+        std::fs::File::open(&tmp)?.sync_all()?;
+        std::fs::rename(&tmp, &path)?;
+        std::fs::File::open(parent)?.sync_all()?;
+        Ok(id)
+    }
+
     /// Persistent state: inode map / cache index DB lives here.
     pub fn state_dir(&self) -> PathBuf {
         // `state_dir` is Linux-only in `directories`; fall back to data dir.
@@ -471,6 +576,12 @@ impl AppDirs {
     }
 }
 
+/// Whether `id` is what [`AppDirs::machine_id`] writes: 32 lowercase hex
+/// digits.
+fn is_machine_id(id: &str) -> bool {
+    id.len() == 32 && id.bytes().all(|b| matches!(b, b'0'..=b'9' | b'a'..=b'f'))
+}
+
 /// Make `dir` owner-only (`0700`). These directories contain decrypted bytes,
 /// plaintext names, and an authenticated control socket, so failure is fatal.
 fn restrict_dir(dir: &Path) -> Result<()> {
@@ -526,6 +637,28 @@ mod tests {
         std::fs::metadata(p).unwrap().permissions().mode() & 0o777
     }
 
+    /// A damaged config must not be replaced by defaults the next time a
+    /// setting changes (`docs/BUGS.md` B223).
+    #[test]
+    fn an_unreadable_config_is_never_written_over() {
+        let dir = std::env::temp_dir().join(format!(
+            "pdfs-cfg-guard-{}-{:?}",
+            std::process::id(),
+            std::thread::current().id()
+        ));
+        let _ = std::fs::remove_dir_all(&dir);
+        std::fs::create_dir_all(&dir).unwrap();
+        let path = dir.join("config.json");
+
+        assert!(refuse_to_replace_unreadable(&path).is_ok(), "no file yet");
+        std::fs::write(&path, serde_json::to_vec(&AppConfig::default()).unwrap()).unwrap();
+        assert!(refuse_to_replace_unreadable(&path).is_ok());
+        std::fs::write(&path, br#"{"mountpoint": "/home/me/Pro"#).unwrap();
+        assert!(refuse_to_replace_unreadable(&path).is_err(), "truncated");
+
+        let _ = std::fs::remove_dir_all(&dir);
+    }
+
     /// `docs/BUGS.md` B6. A permissive mode here is not a cosmetic problem: these
     /// directories hold decrypted content, a plaintext index of every node name,
     /// and the control socket that commands the daemon's session.
@@ -611,6 +744,11 @@ mod tests {
                 descending: true,
                 folders_first: false,
             },
+            window: WindowState {
+                width: 1200,
+                height: 800,
+                maximized: true,
+            },
             tray_hidden: true,
             language: Some("de".to_string()),
             online_map: true,
@@ -630,6 +768,39 @@ mod tests {
         assert_eq!(decoded.upload_limit, Some(500_000));
         assert_eq!(decoded.download_limit, None);
         assert_eq!(decoded.files_view, config.files_view);
+        assert_eq!(decoded.window, config.window);
+    }
+
+    #[test]
+    fn a_config_without_a_window_opens_at_the_default_size() {
+        let decoded: AppConfig =
+            serde_json::from_str(r#"{"app_version":"a","user_agent":"b"}"#).unwrap();
+        assert_eq!(decoded.window, WindowState::default());
+        let partial: WindowState = serde_json::from_str(r#"{"maximized":true}"#).unwrap();
+        assert_eq!((partial.width, partial.height), (980, 680));
+        assert!(partial.maximized);
+    }
+
+    #[test]
+    fn a_window_saved_too_small_opens_at_the_default_size() {
+        let tiny = WindowState {
+            width: 0,
+            height: 500,
+            maximized: true,
+        };
+        assert_eq!(
+            tiny.usable(),
+            WindowState {
+                maximized: true,
+                ..WindowState::default()
+            }
+        );
+        let fine = WindowState {
+            width: 640,
+            height: 480,
+            maximized: false,
+        };
+        assert_eq!(fine.usable(), fine);
     }
 
     #[test]
@@ -760,6 +931,15 @@ mod tests {
         assert_eq!(decoded.conflict_sweep, Some(SweepMode::Enforce));
     }
 
+    #[test]
+    fn a_machine_id_is_32_lowercase_hex_digits() {
+        assert!(is_machine_id("0123456789abcdef0123456789abcdef"));
+        assert!(!is_machine_id("0123456789ABCDEF0123456789ABCDEF"));
+        assert!(!is_machine_id("0123456789abcdef"));
+        assert!(!is_machine_id("../../../../etc/passwd/0123456789"));
+        assert!(!is_machine_id(""));
+    }
+
     #[test]
     fn a_config_predating_ignore_patterns_still_loads() {
         // Every installed config on disk looks like this; the field must not be

crates/pdfs-core/src/control.rs

@@ -1591,6 +1591,10 @@ pub struct RedateSummary {
     /// name implies)` — what a dry run is read for.
     #[serde(default)]
     pub samples: Vec<(String, i64, i64)>,
+    /// Why the run as a whole failed, when it did. The counts are then
+    /// empty: the run never got to the photos.
+    #[serde(default)]
+    pub error: Option<String>,
 }
 
 /// How a Google Photos Takeout import is going, or how the last one ended
@@ -1620,6 +1624,10 @@ pub struct ImportSummary {
     pub bytes: u64,
     /// True when the run stopped early because it was cancelled.
     pub cancelled: bool,
+    /// Why the run as a whole failed, when it did, such as an archive that
+    /// is not a zip. The counts are then empty.
+    #[serde(default)]
+    pub error: Option<String>,
 }
 
 /// One album in a [`Response::Albums`] listing.

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

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

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

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

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

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

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

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

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

@@ -279,6 +279,45 @@ fn claimable() -> String {
 /// drain replaces it with the uid the server assigns.
 pub const LOCAL_VOLUME: &str = "local";
 
+/// One place a queued create was sent, with when it first was.
+struct SentTarget {
+    parent: String,
+    name: String,
+    at_ms: Option<i64>,
+}
+
+/// The `sent_to` column: `[[parent, name, at_ms], …]`, or `[[parent, name], …]`
+/// as written before the time was kept. `None` when it does not parse.
+fn parse_sent_to(json: Option<&str>) -> Option<Vec<SentTarget>> {
+    #[derive(Deserialize)]
+    #[serde(untagged)]
+    enum Entry {
+        At(String, String, i64),
+        Bare(String, String),
+    }
+    let Some(json) = json else {
+        return Some(Vec::new());
+    };
+    let entries: Vec<Entry> = serde_json::from_str(json).ok()?;
+    Some(
+        entries
+            .into_iter()
+            .map(|entry| match entry {
+                Entry::At(parent, name, at) => SentTarget {
+                    parent,
+                    name,
+                    at_ms: Some(at),
+                },
+                Entry::Bare(parent, name) => SentTarget {
+                    parent,
+                    name,
+                    at_ms: None,
+                },
+            })
+            .collect(),
+    )
+}
+
 /// The uid a node made on this machine goes by until Drive gives it one: its
 /// row's local id under [`LOCAL_VOLUME`].
 ///
@@ -541,7 +580,7 @@ impl Db {
     /// land in the order they were made (`docs/BUGS.md` B141). Should it fail,
     /// [`Db::record_op_failure`] or [`Db::release_op_claim`] drops it.
     pub fn enqueue_op(&self, op: &PendingOp) -> Result<(i64, Option<String>)> {
-        let mut conn = self.conn.lock();
+        let mut conn = self.durable()?;
         let tx = conn.transaction()?;
         let superseded: Option<String> = if op_supersedes(&op.kind) {
             let lid = node_lid(&tx, &op.uid)?;
@@ -598,7 +637,7 @@ impl Db {
         name: &str,
         created_at: i64,
     ) -> Result<(i64, Vec<String>)> {
-        let mut conn = self.conn.lock();
+        let mut conn = self.durable()?;
         let tx = conn.transaction()?;
         let blobs = drop_doomed_ops(&tx, uid)?;
         tx.execute(
@@ -628,7 +667,7 @@ impl Db {
         blob_path: &str,
         meta_json: &str,
     ) -> Result<Option<AttachedBlob>> {
-        let conn = self.conn.lock();
+        let conn = self.durable()?;
         let lid = node_lid(&conn, uid)?;
         let existing: Option<(i64, Option<String>)> = conn
             .query_row(
@@ -691,7 +730,7 @@ impl Db {
         rewrite: impl FnOnce(&str) -> Option<String>,
     ) -> Result<CreateRetired> {
         let (local, real) = (landing.local, landing.real);
-        let mut conn = self.conn.lock();
+        let mut conn = self.durable()?;
         let tx = conn.transaction()?;
         let row: Option<CreateRow> = tx
             .query_row(
@@ -808,12 +847,19 @@ impl Db {
         Ok(())
     }
 
-    /// Record that queued create `id` is being sent to `parent` under `name`.
+    /// Record that queued create `id` is being sent to `parent` under `name`
+    /// at `at_ms`.
     ///
     /// A rename while the op waits rewrites its target, but the file a lost
     /// answer left stays where it was sent. The retry and the trash look
-    /// there too (`docs/BUGS.md` B184).
-    pub fn note_create_target(&self, id: i64, parent: &str, name: &str) -> Result<()> {
+    /// there too (`docs/BUGS.md` B184). A target sent before keeps its first
+    /// time.
+    ///
+    /// A record that does not parse is left as it is rather than replaced
+    /// with this one target: the earlier ones are what the duplicate checks
+    /// look for. Without them a lost answer forks a conflict copy, which
+    /// loses nothing.
+    pub fn note_create_target(&self, id: i64, parent: &str, name: &str, at_ms: i64) -> Result<()> {
         let mut conn = self.conn.lock();
         let tx = conn.transaction()?;
         let sent: Option<String> = tx
@@ -822,15 +868,26 @@ impl Db {
             })
             .optional()?
             .flatten();
-        let mut targets: Vec<(String, String)> = sent
-            .and_then(|json| serde_json::from_str(&json).ok())
-            .unwrap_or_default();
-        let target = (parent.to_string(), name.to_string());
-        if !targets.contains(&target) {
-            targets.push(target);
+        let Some(mut targets) = parse_sent_to(sent.as_deref()) else {
+            tracing::warn!(
+                id,
+                "a queued create's send record does not parse; keeping it"
+            );
+            return Ok(());
+        };
+        if !targets.iter().any(|t| t.parent == parent && t.name == name) {
+            targets.push(SentTarget {
+                parent: parent.to_string(),
+                name: name.to_string(),
+                at_ms: Some(at_ms),
+            });
+            let json: Vec<(&str, &str, i64)> = targets
+                .iter()
+                .map(|t| (t.parent.as_str(), t.name.as_str(), t.at_ms.unwrap_or(0)))
+                .collect();
             tx.execute(
                 "UPDATE pending_op SET sent_to = ?2 WHERE id = ?1",
-                params![id, serde_json::to_string(&targets)?],
+                params![id, serde_json::to_string(&json)?],
             )?;
         }
         tx.commit()?;
@@ -840,6 +897,24 @@ impl Db {
     /// The parent and name queued op `id` was sent under as a create, in the
     /// order it was ([`Db::note_create_target`]).
     pub fn create_targets(&self, id: i64) -> Result<Vec<(String, String)>> {
+        Ok(self
+            .sent_targets(id)?
+            .into_iter()
+            .map(|t| (t.parent, t.name))
+            .collect())
+    }
+
+    /// When queued create `id` was first sent, if that was recorded. Rows
+    /// written before the time was kept have none.
+    pub fn create_first_sent(&self, id: i64) -> Result<Option<i64>> {
+        Ok(self
+            .sent_targets(id)?
+            .into_iter()
+            .filter_map(|t| t.at_ms.filter(|&at| at > 0))
+            .min())
+    }
+
+    fn sent_targets(&self, id: i64) -> Result<Vec<SentTarget>> {
         let sent: Option<String> = self
             .conn
             .lock()
@@ -848,9 +923,7 @@ impl Db {
             })
             .optional()?
             .flatten();
-        Ok(sent
-            .and_then(|json| serde_json::from_str(&json).ok())
-            .unwrap_or_default())
+        Ok(parse_sent_to(sent.as_deref()).unwrap_or_default())
     }
 
     /// The SHA-1 of each blob queued op `id` sent as a create
@@ -898,6 +971,27 @@ impl Db {
         Ok(n > 0)
     }
 
+    /// Replace the sidecar of op `id`, but only while it still holds the blob
+    /// at `blob_path`.
+    ///
+    /// The drain fills an incomplete blob in place and then records it as
+    /// whole, so a retry after a lost answer can recognise its own bytes on the
+    /// server. A write that closed meanwhile has pointed the row at a newer
+    /// blob with its own sidecar; that one must not be overwritten. Returns
+    /// false when the row is gone or holds another blob.
+    pub fn update_op_meta_for_blob(
+        &self,
+        id: i64,
+        blob_path: &str,
+        meta_json: &str,
+    ) -> Result<bool> {
+        let n = self.conn.lock().execute(
+            "UPDATE pending_op SET meta_json = ?3 WHERE id = ?1 AND blob_path = ?2",
+            params![id, blob_path, meta_json],
+        )?;
+        Ok(n > 0)
+    }
+
     /// Point a queued create at a new parent and name, for a node renamed or
     /// moved before it ever reached the server.
     ///
@@ -911,7 +1005,7 @@ impl Db {
     /// name it no longer wants, such as one held by a queued change. A parked
     /// create stays parked.
     pub fn rewrite_op_target(&self, uid: &str, parent_uid: &str, name: &str) -> Result<bool> {
-        let conn = self.conn.lock();
+        let conn = self.durable()?;
         let lid = node_lid(&conn, uid)?;
         let parent_lid = node_lid(&conn, parent_uid)?;
         let n = conn.execute(
@@ -1389,12 +1483,26 @@ impl Db {
     }
 
     /// [`retry_op_now`](Self::retry_op_now) for every op that has failed at
-    /// least once. Returns how many rows changed.
+    /// least once, for the user's "Retry all". Returns how many rows changed.
     pub fn retry_failed_ops_now(&self, now: i64) -> Result<usize> {
+        self.retry_ops_now(now, "")
+    }
+
+    /// [`retry_failed_ops_now`](Self::retry_failed_ops_now) for the ops Drive
+    /// did not refuse, for a reconnect. A link coming back changes nothing
+    /// about a full quota or a missing permission, so those keep their backoff
+    /// instead of all being sent again at once.
+    pub fn retry_unrefused_ops_now(&self, now: i64) -> Result<usize> {
+        self.retry_ops_now(now, "AND issue IS NULL")
+    }
+
+    fn retry_ops_now(&self, now: i64, filter: &str) -> Result<usize> {
         let conn = self.conn.lock();
         let changed = conn.execute(
+            &format!(
                 "UPDATE pending_op SET next_attempt_at = ?1
-             WHERE attempts > 0 AND next_attempt_at > ?1 AND next_attempt_at < ?2",
+                 WHERE attempts > 0 AND next_attempt_at > ?1 AND next_attempt_at < ?2 {filter}"
+            ),
             params![now, PARK_UNTIL],
         )?;
         Ok(changed)

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

@@ -45,6 +45,12 @@ pub struct StoredSyncEntry {
     pub local_mtime_ns: Option<i64>,
     pub remote_rev: Option<String>,
     pub remote_hash: Option<String>,
+    /// The id of the remote revision this row was synced at. A mirror upload
+    /// checks it before it supersedes what Drive holds, because another client
+    /// may have committed a revision since (`docs/BUGS.md` B249). `None` on a
+    /// row written before schema 44, or by a pass that did not learn it; the
+    /// check then falls back to `remote_rev` and `remote_hash`.
+    pub remote_revision_id: Option<String>,
 }
 
 impl Db {
@@ -188,7 +194,7 @@ impl Db {
         let conn = self.read();
         let mut stmt = conn.prepare(
             "SELECT rel_path, remote_uid, local_mtime, local_size, remote_rev, remote_hash,
-                    local_mtime_ns
+                    local_mtime_ns, remote_revision_id
              FROM sync_entry WHERE folder_id = ?1",
         )?;
         let rows = stmt.query_map(params![folder_id], |r| {
@@ -200,6 +206,7 @@ impl Db {
                 remote_rev: r.get(4)?,
                 remote_hash: r.get(5)?,
                 local_mtime_ns: r.get(6)?,
+                remote_revision_id: r.get(7)?,
             })
         })?;
         let mut map = HashMap::new();
@@ -238,15 +245,16 @@ impl Db {
         conn.execute(
             "INSERT INTO sync_entry
                (folder_id, rel_path, remote_uid, local_mtime, local_size, remote_rev,
-                remote_hash, local_mtime_ns)
-             VALUES (?1, ?2, ?3, ?4, ?5, ?6, ?7, ?8)
+                remote_hash, local_mtime_ns, remote_revision_id)
+             VALUES (?1, ?2, ?3, ?4, ?5, ?6, ?7, ?8, ?9)
              ON CONFLICT(folder_id, rel_path) DO UPDATE SET
                remote_uid         = excluded.remote_uid,
                local_mtime        = excluded.local_mtime,
                local_size         = excluded.local_size,
                remote_rev         = excluded.remote_rev,
                remote_hash        = excluded.remote_hash,
-               local_mtime_ns = excluded.local_mtime_ns",
+               local_mtime_ns     = excluded.local_mtime_ns,
+               remote_revision_id = excluded.remote_revision_id",
             params![
                 folder_id,
                 e.rel_path,
@@ -256,6 +264,7 @@ impl Db {
                 e.remote_rev,
                 e.remote_hash,
                 e.local_mtime_ns,
+                e.remote_revision_id,
             ],
         )?;
         Ok(())
@@ -306,7 +315,7 @@ impl Db {
         {
             let mut select = tx.prepare(
                 "SELECT rel_path, remote_uid, local_mtime, local_size, remote_rev, remote_hash,
-                        local_mtime_ns
+                        local_mtime_ns, remote_revision_id
                    FROM sync_entry
                   WHERE folder_id = ?1
                     AND (rel_path = ?2 OR substr(rel_path, 1, length(?2) + 1) = ?2 || '/')",
@@ -321,6 +330,7 @@ impl Db {
                         remote_rev: r.get(4)?,
                         remote_hash: r.get(5)?,
                         local_mtime_ns: r.get(6)?,
+                        remote_revision_id: r.get(7)?,
                     })
                 })?
                 .collect::<rusqlite::Result<Vec<_>>>()?;
@@ -332,8 +342,8 @@ impl Db {
             let mut insert = tx.prepare(
                 "INSERT OR REPLACE INTO sync_entry
                    (folder_id, rel_path, remote_uid, local_mtime, local_size, remote_rev,
-                    remote_hash, local_mtime_ns)
-                 VALUES (?1, ?2, ?3, ?4, ?5, ?6, ?7, ?8)",
+                    remote_hash, local_mtime_ns, remote_revision_id)
+                 VALUES (?1, ?2, ?3, ?4, ?5, ?6, ?7, ?8, ?9)",
             )?;
             for row in rows {
                 let rel = format!("{to_rel}{}", &row.rel_path[from_rel.len()..]);
@@ -346,6 +356,7 @@ impl Db {
                     row.remote_rev,
                     row.remote_hash,
                     row.local_mtime_ns,
+                    row.remote_revision_id,
                 ])?;
             }
         }

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

@@ -1283,6 +1283,90 @@ fn a_corrupt_database_is_moved_aside_and_rebuilt() {
     let _ = std::fs::remove_file(path.with_extension("db.lock"));
 }
 
+/// A rebuilt database must not lose what only this machine has: writes Drive
+/// has not received, the mirror baselines and the pins (`docs/BUGS.md` B216).
+#[test]
+fn a_rebuild_keeps_the_queue_baselines_and_pins_of_the_damaged_file() {
+    let id = now_test_id();
+    let damaged =
+        std::env::temp_dir().join(format!("pdfs-salvage-old-{}-{id}.db", std::process::id()));
+    let fresh =
+        std::env::temp_dir().join(format!("pdfs-salvage-new-{}-{id}.db", std::process::id()));
+
+    let db = Db::open(&damaged).unwrap();
+    db.upsert_node(&folder("root", None, "My Files")).unwrap();
+    db.upsert_node(&file("listed", "root", "listed.txt", 1))
+        .unwrap();
+    db.upsert_node(&file("queued", "root", "queued.txt", 2))
+        .unwrap();
+    db.set_listed(&uid("root"), true).unwrap();
+    db.enqueue_op(&PendingOp {
+        id: 0,
+        kind: OP_REVISION.to_string(),
+        uid: uid("queued").to_string(),
+        parent_uid: None,
+        name: None,
+        blob_path: Some("/staging/queued".into()),
+        meta_json: None,
+        created_at: 1,
+        attempts: 3,
+        last_error: None,
+        next_attempt_at: 0,
+    })
+    .unwrap();
+    let folder_id = db
+        .sync_folder_add("/home/me/Docs", "vol~docs", "share")
+        .unwrap();
+    db.sync_entry_upsert(
+        folder_id,
+        &StoredSyncEntry {
+            rel_path: "a.txt".into(),
+            remote_uid: Some("vol~a".into()),
+            local_mtime: 5,
+            local_mtime_ns: None,
+            local_size: 6,
+            remote_rev: Some("7".into()),
+            remote_hash: Some("8".into()),
+            remote_revision_id: None,
+        },
+    )
+    .unwrap();
+    db.pin_add("vol~pinned", "/pinned", true).unwrap();
+    drop(db);
+
+    let db = Db::open(&fresh).unwrap();
+    let results = salvage(&db.conn.lock(), &damaged);
+    assert!(results.iter().all(|(_, r)| r.is_ok()), "{results:?}");
+
+    let ops = db.pending_ops().unwrap();
+    assert_eq!(ops.len(), 1);
+    assert_eq!(ops[0].uid, uid("queued").to_string());
+    assert_eq!(ops[0].blob_path.as_deref(), Some("/staging/queued"));
+    // The op's node came with it; the rest of the tree is fetched again.
+    assert!(
+        db.node_by_uid(&uid("queued").to_string())
+            .unwrap()
+            .is_some()
+    );
+    assert!(
+        db.node_by_uid(&uid("listed").to_string())
+            .unwrap()
+            .is_none()
+    );
+    assert_eq!(db.sync_entries(folder_id).unwrap().len(), 1);
+    assert!(db.is_pinned("vol~pinned").unwrap());
+    drop(db);
+
+    for path in [&damaged, &fresh] {
+        for suffix in ["", "-wal", "-shm"] {
+            let mut file = path.as_os_str().to_owned();
+            file.push(suffix);
+            let _ = std::fs::remove_file(std::path::PathBuf::from(file));
+        }
+        let _ = std::fs::remove_file(path.with_extension("db.lock"));
+    }
+}
+
 fn local(path: &str, name: &str, is_dir: bool) -> LocalEntry {
     LocalEntry {
         path: path.into(),
@@ -1346,6 +1430,77 @@ fn rescanning_an_unchanged_file_keeps_exactly_one_index_entry() {
     }
 }
 
+/// A scan that stopped early or lost a batch did not see every file, so it
+/// must not prune the ones it missed (`docs/BUGS.md` B217).
+#[test]
+fn a_partial_local_scan_prunes_nothing() {
+    let db = Db::open_in_memory().unwrap();
+    let g = db.local_begin_scan().unwrap();
+    db.local_upsert_batch(
+        g,
+        &[
+            local("/home/u/a.txt", "a.txt", false),
+            local("/home/u/b.txt", "b.txt", false),
+        ],
+    )
+    .unwrap();
+    assert_eq!(db.local_finish_scan(g, 1).unwrap(), 2);
+
+    let g = db.local_begin_scan().unwrap();
+    db.local_upsert_batch(g, &[local("/home/u/a.txt", "a.txt", false)])
+        .unwrap();
+    assert_eq!(db.local_finish_partial_scan(2).unwrap(), 2);
+    assert_eq!(db.search_local("b.txt", 10).unwrap().len(), 1);
+    assert_eq!(db.local_indexed_at().unwrap(), Some(2));
+}
+
+/// Deleted entries pile up in an FTS5 index until it is compacted. The daily
+/// compaction must leave both indexes whole and searchable, and must not run
+/// again the same day (`docs/BUGS.md` B217).
+#[test]
+fn compacting_the_search_indexes_keeps_them_whole_and_runs_once_a_day() {
+    let db = Db::open_in_memory().unwrap();
+    db.upsert_node(&folder("root", None, "My Files")).unwrap();
+    db.upsert_node(&file("f1", "root", "quarterly-report.pdf", 1))
+        .unwrap();
+    for round in 0..20 {
+        let g = db.local_begin_scan().unwrap();
+        let name = format!("churn-{round}.txt");
+        db.local_upsert_batch(
+            g,
+            &[
+                local("/home/u/keep.txt", "keep.txt", false),
+                local(&format!("/home/u/{name}"), &name, false),
+            ],
+        )
+        .unwrap();
+        // Far in the past, so no scan compacts on its own.
+        db.local_finish_scan(g, 0).unwrap();
+    }
+
+    let day = 24 * 60 * 60;
+    db.compact_search_indexes_if_due(day).unwrap();
+    {
+        let conn = db.conn.lock();
+        for table in ["local_fts", "nodes_fts"] {
+            conn.execute(
+                &format!("INSERT INTO {table}({table}) VALUES('integrity-check')"),
+                [],
+            )
+            .unwrap();
+        }
+    }
+    assert_eq!(db.search_local("keep", 10).unwrap().len(), 1);
+    assert_eq!(db.search_local("churn-19", 10).unwrap().len(), 1);
+    assert!(db.search_local("churn-3.txt", 10).unwrap().is_empty());
+    assert_eq!(db.search("quarterly", 10).unwrap().len(), 1);
+    let stamp = |db: &Db| db.state_str("fts_compacted_at").unwrap();
+    assert_eq!(stamp(&db).as_deref(), Some(day.to_string().as_str()));
+
+    db.compact_search_indexes_if_due(day + 60).unwrap();
+    assert_eq!(stamp(&db).as_deref(), Some(day.to_string().as_str()));
+}
+
 /// Queries below the trigram minimum still match, via the `LIKE` fallback.
 #[test]
 fn local_search_short_query_like_fallback() {
@@ -2198,6 +2353,100 @@ fn refuses_a_schema_newer_than_the_running_build() {
     let _ = std::fs::remove_file(path);
 }
 
+/// Queueing a write syncs it to disk, and leaves the writer at NORMAL after.
+///
+/// The op row is what makes a staged blob reachable once `close()` has
+/// reported success, so its commit must survive a power loss. Everything else
+/// the writer commits is metadata the next listing re-fetches, and pays only
+/// NORMAL's cost.
+#[test]
+fn queueing_a_write_commits_at_full_sync_and_restores_normal() {
+    let path = std::env::temp_dir().join(format!("pdfs-db-sync-{}.db", std::process::id()));
+    let _ = std::fs::remove_file(&path);
+    let db = Db::open(&path).unwrap();
+    let level = |db: &Db| -> i64 {
+        db.conn
+            .lock()
+            .query_row("PRAGMA synchronous", [], |r| r.get(0))
+            .unwrap()
+    };
+    // 1 = NORMAL, 2 = FULL.
+    assert_eq!(level(&db), 1);
+    {
+        let durable = db.durable().unwrap();
+        let during: i64 = durable
+            .query_row("PRAGMA synchronous", [], |r| r.get(0))
+            .unwrap();
+        assert_eq!(during, 2);
+    }
+    assert_eq!(level(&db), 1);
+
+    db.enqueue_op(&PendingOp {
+        id: 0,
+        kind: OP_TRASH.to_string(),
+        uid: uid("a").to_string(),
+        parent_uid: None,
+        name: Some("a".to_string()),
+        blob_path: None,
+        meta_json: None,
+        created_at: 1,
+        attempts: 0,
+        last_error: None,
+        next_attempt_at: 0,
+    })
+    .unwrap();
+    assert_eq!(level(&db), 1);
+    assert_eq!(db.pending_ops().unwrap().len(), 1);
+    drop(db);
+    for suffix in ["", "-wal", "-shm"] {
+        let _ = std::fs::remove_file(format!("{}{suffix}", path.display()));
+    }
+}
+
+/// A gap-filled blob is recorded as whole only while the op still holds it.
+///
+/// A write that closes during the drain points the row at a newer blob with
+/// its own sidecar. Overwriting that sidecar with the older blob's would
+/// describe bytes the row no longer holds.
+#[test]
+fn marking_a_blob_whole_leaves_a_newer_blob_alone() {
+    let db = Db::open_in_memory().unwrap();
+    let op = PendingOp {
+        id: 0,
+        kind: OP_REVISION.to_string(),
+        uid: uid("a").to_string(),
+        parent_uid: None,
+        name: None,
+        blob_path: Some("/staging/first".to_string()),
+        meta_json: Some(r#"{"complete":false}"#.to_string()),
+        created_at: 1,
+        attempts: 0,
+        last_error: None,
+        next_attempt_at: 0,
+    };
+    db.enqueue_op(&op).unwrap();
+    let id = db.pending_ops().unwrap()[0].id;
+
+    assert!(
+        db.update_op_meta_for_blob(id, "/staging/first", r#"{"complete":true}"#)
+            .unwrap()
+    );
+    assert_eq!(
+        db.pending_ops().unwrap()[0].meta_json.as_deref(),
+        Some(r#"{"complete":true}"#)
+    );
+
+    assert!(
+        !db.update_op_meta_for_blob(id, "/staging/older", r#"{"stale":true}"#)
+            .unwrap(),
+        "the row holds another blob"
+    );
+    assert_eq!(
+        db.pending_ops().unwrap()[0].meta_json.as_deref(),
+        Some(r#"{"complete":true}"#)
+    );
+}
+
 /// A queued write whose baseline is restamped must keep everything else.
 ///
 /// The restamp happens after our *own* upload seals a new revision under a
@@ -3927,15 +4176,15 @@ fn what_a_create_sent_outlives_a_newer_blob_its_trash_and_a_restart() {
             .unwrap();
         assert!(db.create_sent(id).unwrap().is_empty());
         assert!(db.create_targets(id).unwrap().is_empty());
-        db.note_create_target(id, &parent, "c").unwrap();
-        db.note_create_target(id, &parent, "c").unwrap();
+        db.note_create_target(id, &parent, "c", 10).unwrap();
+        db.note_create_target(id, &parent, "c", 20).unwrap();
         db.note_create_sent(id, "aaaa").unwrap();
         db.note_create_sent(id, "aaaa").unwrap();
         db.record_op_failure(id, "no answer", 0).unwrap();
         db.attach_blob_to_create("local~sent", "/staging/second", "{}")
             .unwrap()
             .expect("the create is still queued");
-        db.note_create_target(id, &parent, "d").unwrap();
+        db.note_create_target(id, &parent, "d", 30).unwrap();
         db.note_create_sent(id, "bbbb").unwrap();
         db.record_op_failure(id, "no answer", 0).unwrap();
         db.delete_ops_for_uid("local~sent").unwrap();
@@ -3958,6 +4207,73 @@ fn what_a_create_sent_outlives_a_newer_blob_its_trash_and_a_restart() {
     let _ = std::fs::remove_file(path);
 }
 
+/// A queued create knows when it first went out, which is where the window
+/// for adopting a node its lost answer left starts. Records written before
+/// the time was kept still list their targets, and one that does not parse is
+/// not replaced by the next target.
+#[test]
+fn a_create_remembers_when_it_was_first_sent() {
+    let db = Db::open_in_memory().unwrap();
+    let parent = uid("parent").to_string();
+    let (id, _) = db
+        .enqueue_op(&PendingOp {
+            id: 0,
+            kind: OP_CREATE.to_string(),
+            uid: "local~first".to_string(),
+            parent_uid: Some(parent.clone()),
+            name: Some("a.txt".to_string()),
+            blob_path: None,
+            meta_json: None,
+            created_at: 1,
+            attempts: 0,
+            last_error: None,
+            next_attempt_at: 0,
+        })
+        .unwrap();
+    assert_eq!(db.create_first_sent(id).unwrap(), None, "never sent");
+    db.note_create_target(id, &parent, "a.txt", 500).unwrap();
+    db.note_create_target(id, &parent, "a.txt", 900).unwrap();
+    db.note_create_target(id, &parent, "b.txt", 700).unwrap();
+    assert_eq!(db.create_first_sent(id).unwrap(), Some(500));
+
+    let set = |json: &str| {
+        db.conn
+            .lock()
+            .execute(
+                "UPDATE pending_op SET sent_to = ?2 WHERE id = ?1",
+                rusqlite::params![id, json],
+            )
+            .unwrap();
+    };
+    set(&format!(r#"[["{parent}","old.txt"]]"#));
+    assert_eq!(
+        db.create_targets(id).unwrap(),
+        vec![(parent.clone(), "old.txt".to_string())]
+    );
+    assert_eq!(db.create_first_sent(id).unwrap(), None);
+    db.note_create_target(id, &parent, "a.txt", 900).unwrap();
+    assert_eq!(
+        db.create_targets(id).unwrap().len(),
+        2,
+        "the old target stays"
+    );
+    assert_eq!(db.create_first_sent(id).unwrap(), Some(900));
+
+    set("not json");
+    db.note_create_target(id, &parent, "c.txt", 1000).unwrap();
+    let raw: String = db
+        .conn
+        .lock()
+        .query_row("SELECT sent_to FROM pending_op WHERE id = ?1", [id], |r| {
+            r.get(0)
+        })
+        .unwrap();
+    assert_eq!(
+        raw, "not json",
+        "an unreadable record is kept, not replaced"
+    );
+}
+
 /// A write after a create failed clears its attempts, so the next try goes
 /// out at once. The create was still sent: deleting the file then left no
 /// trash, and the file a lost answer made stayed on Drive under the name it
@@ -3981,7 +4297,7 @@ fn a_create_rewritten_after_it_failed_still_leaves_a_trash_when_deleted() {
             next_attempt_at: 0,
         })
         .unwrap();
-    db.note_create_target(id, &parent, "a.txt").unwrap();
+    db.note_create_target(id, &parent, "a.txt", 10).unwrap();
     db.note_create_sent(id, "aaaa").unwrap();
     db.record_op_failure(id, "no answer", 0).unwrap();
     db.attach_blob_to_create("local~sent", "/staging/second", "{}")
@@ -5028,6 +5344,7 @@ fn baseline_row(rel: &str) -> StoredSyncEntry {
         local_size: 7,
         remote_rev: Some("1700000000".into()),
         remote_hash: Some("7".into()),
+        remote_revision_id: None,
     }
 }
 
@@ -5122,6 +5439,7 @@ fn mirror_uid_lookup_covers_the_root_and_synced_descendants_only() {
             local_size: 2,
             remote_rev: Some("3".into()),
             remote_hash: Some("2".into()),
+            remote_revision_id: None,
             local_mtime_ns: None,
         },
     )
@@ -5139,6 +5457,7 @@ fn mirror_uid_lookup_covers_the_root_and_synced_descendants_only() {
             local_size: 2,
             remote_rev: Some("3".into()),
             remote_hash: Some("2".into()),
+            remote_revision_id: None,
             local_mtime_ns: None,
         },
     )
@@ -6316,6 +6635,71 @@ fn migration_v27_adds_the_access_deferral_column_to_a_v26_queue() {
     let _ = std::fs::remove_file(format!("{}.lock", path.display()));
 }
 
+/// V44 adds the remote revision a baseline row was synced at. A row carried
+/// over from V43 has none, and the mirror then compares the modification time
+/// and size as before, so upgrading changes nothing about what is in step
+/// (`docs/BUGS.md` B249).
+#[test]
+fn migration_v44_adds_the_synced_revision_without_disturbing_a_v43_baseline() {
+    let path = std::env::temp_dir().join(format!(
+        "pdfs-db-v43-fixture-{}-{}.db",
+        std::process::id(),
+        std::time::SystemTime::now()
+            .duration_since(std::time::UNIX_EPOCH)
+            .unwrap()
+            .as_nanos()
+    ));
+    let row = StoredSyncEntry {
+        rel_path: "notes.txt".into(),
+        remote_uid: Some("vol~notes".into()),
+        local_mtime: 1_700_000_000,
+        local_mtime_ns: Some(1_700_000_000_123_456_789),
+        local_size: 42,
+        remote_rev: Some("1700000000".into()),
+        remote_hash: Some("42".into()),
+        remote_revision_id: Some("rev-1".into()),
+    };
+    {
+        let db = Db::open(&path).unwrap();
+        let folder = db
+            .sync_folder_add("/home/me/Mirror", "vol~root", "share")
+            .unwrap();
+        db.sync_entry_upsert(folder, &row).unwrap();
+    }
+    {
+        // Put the file back in the state a released V43 database was in.
+        let conn = rusqlite::Connection::open(&path).unwrap();
+        conn.execute_batch(
+            "ALTER TABLE sync_entry DROP COLUMN remote_revision_id;
+             UPDATE sync_state SET value = '43' WHERE key = 'schema_version';",
+        )
+        .unwrap();
+    }
+
+    let db = Db::open(&path).unwrap();
+    let entries = db.sync_entries(1).unwrap();
+    let entry = entries.get("notes.txt").expect("the baseline row survives");
+    assert_eq!(
+        entry,
+        &StoredSyncEntry {
+            remote_revision_id: None,
+            ..row.clone()
+        }
+    );
+
+    // And the column is live, including through a move of the row.
+    db.sync_entry_upsert(1, &row).unwrap();
+    db.sync_entries_move(1, "notes.txt", 1, "moved.txt")
+        .unwrap();
+    let entries = db.sync_entries(1).unwrap();
+    assert_eq!(
+        entries["moved.txt"].remote_revision_id.as_deref(),
+        Some("rev-1")
+    );
+    drop(db);
+    let _ = std::fs::remove_file(&path);
+}
+
 /// A mirror baseline carried over from V27 keeps its rows, and each one reads
 /// back with no nanosecond time. That `None` is the whole point: it makes the
 /// comparison fall back to whole seconds for rows written before the column
@@ -6346,6 +6730,7 @@ fn migration_v28_adds_sub_second_local_times_without_disturbing_a_v27_baseline()
                 local_size: 42,
                 remote_rev: Some("1700000000".into()),
                 remote_hash: Some("42".into()),
+                remote_revision_id: None,
             },
         )
         .unwrap();
@@ -7216,6 +7601,56 @@ fn a_refused_change_names_its_node_by_local_id() {
     );
 }
 
+/// The name checks the drain makes before each op look the name up in an
+/// index. Scanning the queue instead made a large offline batch quadratic.
+#[test]
+fn queue_name_checks_use_an_index() {
+    let db = Db::open_in_memory().unwrap();
+    let conn = db.conn.lock();
+    let plan = |sql: &str| -> String {
+        let mut stmt = conn.prepare(&format!("EXPLAIN QUERY PLAN {sql}")).unwrap();
+        stmt.query_map([], |r| r.get::<_, String>(3))
+            .unwrap()
+            .map(|row| row.unwrap())
+            .collect::<Vec<_>>()
+            .join("; ")
+    };
+    for sql in [
+        "SELECT 1 FROM pending_op WHERE kind = 'trash' AND name = 'a'",
+        "SELECT 1 FROM pending_op WHERE name = 'a' AND kind IN ('create', 'mkdir', 'rename')",
+        "SELECT 1 FROM pending_op WHERE kind = 'rename'",
+    ] {
+        let plan = plan(sql);
+        assert!(plan.contains("pending_op_kind_name"), "{sql}: {plan}");
+    }
+}
+
+/// A reconnect moves up the ops that failed for want of a link. One Drive
+/// refused, for quota or access, keeps its backoff: the link coming back
+/// changes nothing about it. "Retry all" still moves both.
+#[test]
+fn a_reconnect_leaves_refused_ops_to_their_backoff() {
+    let db = Db::open_in_memory().unwrap();
+    let offline = queued_op(&db, "vol~a", 2, 90_000);
+    let refused = queued_op(&db, "vol~b", 2, 90_000);
+    db.set_op_issue(refused, Some("quota")).unwrap();
+
+    assert_eq!(db.retry_unrefused_ops_now(5_000).unwrap(), 1);
+    let due = |id: i64| {
+        db.pending_ops()
+            .unwrap()
+            .into_iter()
+            .find(|op| op.id == id)
+            .unwrap()
+            .next_attempt_at
+    };
+    assert_eq!(due(offline), 5_000);
+    assert_eq!(due(refused), 90_000);
+
+    assert_eq!(db.retry_failed_ops_now(5_000).unwrap(), 1);
+    assert_eq!(due(refused), 5_000);
+}
+
 #[test]
 fn retry_all_touches_only_ops_that_have_failed() {
     let db = Db::open_in_memory().unwrap();

crates/pdfs-core/src/exiftime.rs

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

crates/pdfs-core/src/lib.rs

@@ -10,6 +10,7 @@ pub mod config;
 pub mod control;
 pub mod db;
 pub mod error;
+pub mod exiftime;
 pub mod kernelkey;
 pub mod localindex;
 pub mod menu;
@@ -23,6 +24,7 @@ pub mod service;
 pub mod shell;
 pub mod similar;
 pub mod syncignore;
+pub mod syncroot;
 pub mod takeout;
 pub mod tray;
 

crates/pdfs-core/src/localindex.rs

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

crates/pdfs-core/src/opener.rs

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

crates/pdfs-core/src/profile.rs

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

crates/pdfs-core/src/shell.rs

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

crates/pdfs-core/src/syncroot.rs

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

crates/pdfs-core/src/takeout.rs

@@ -346,6 +346,11 @@ fn assemble(entries: Vec<RawEntry>, sidecars: &HashMap<String, Vec<u8>>) -> Take
             .insert(file.to_string(), body);
     }
 
+    let indexes: HashMap<&str, SidecarIndex<'_>> = per_folder_sidecars
+        .iter()
+        .map(|(folder, in_folder)| (folder.as_str(), SidecarIndex::new(in_folder)))
+        .collect();
+
     let mut scan = TakeoutScan::default();
     let mut seen_albums: HashMap<String, ()> = HashMap::new();
 
@@ -364,9 +369,13 @@ fn assemble(entries: Vec<RawEntry>, sidecars: &HashMap<String, Vec<u8>>) -> Take
             continue;
         };
 
-        let sidecar = per_folder_sidecars
-            .get(&folder)
-            .and_then(|in_folder| find_sidecar(&file_name, in_folder))
+        let found = indexes
+            .get(folder.as_str())
+            .and_then(|index| find_sidecar(&file_name, index));
+        // An edited copy keeps its own name: the title is its original's.
+        let title_is_ours = found.is_some_and(|((rule, _), _)| rule != EDITED_COPY);
+        let sidecar = found
+            .map(|(_, body)| body)
             .and_then(|body| serde_json::from_slice::<PhotoSidecar>(body).ok())
             .unwrap_or_default();
 
@@ -388,6 +397,7 @@ fn assemble(entries: Vec<RawEntry>, sidecars: &HashMap<String, Vec<u8>>) -> Take
         let name = sidecar
             .title
             .as_deref()
+            .filter(|_| title_is_ours)
             .map(str::trim)
             .filter(|title| !title.is_empty() && same_extension(title, &file_name))
             .unwrap_or(&file_name)
@@ -598,7 +608,7 @@ pub fn capture_time_from_name(name: &str) -> Option<i64> {
 
 /// Days between 1970-01-01 and a proleptic-Gregorian date (Howard Hinnant's
 /// `days_from_civil`). Avoids pulling a date crate in for one conversion.
-fn days_from_civil(year: i64, month: i64, day: i64) -> i64 {
+pub(crate) fn days_from_civil(year: i64, month: i64, day: i64) -> i64 {
     let year = year - i64::from(month <= 2);
     let era = if year >= 0 { year } else { year - 399 } / 400;
     let year_of_era = year - era * 400;
@@ -627,17 +637,106 @@ fn swap_duplicate_marker(file_name: &str) -> Option<String> {
     Some(format!("{}{}{}", &file_name[..marker_start], tail, marker))
 }
 
-/// Find the sidecar belonging to `file_name` among the JSON files of its folder.
+/// How long Google lets a sidecar's file name get, `.json` included. A longer
+/// one is cut, into its suffix first and then into the photo name.
+const SIDECAR_NAME_CAP: usize = 51;
+
+/// The rank [`sidecar_rank`] gives an edited copy that shares its original's
+/// sidecar. Its date is the original's, but its name is its own.
+const EDITED_COPY: u8 = 4;
+
+/// The sidecars of one folder by their `.json`-stripped stem, so a photo is
+/// ranked only against those that can match it.
+///
+/// Every rule in [`sidecar_rank`] needs the stem to start with a prefix of the
+/// photo name that the name itself determines, and a sorted map finds the
+/// stems with a given prefix as one range. Ranking every photo against every
+/// sidecar instead took 27 s for a folder of 10,000 photos.
+struct SidecarIndex<'a> {
+    by_stem: BTreeMap<&'a str, Vec<(&'a str, &'a Vec<u8>)>>,
+}
+
+impl<'a> SidecarIndex<'a> {
+    fn new(in_folder: &'a BTreeMap<String, &'a Vec<u8>>) -> Self {
+        let mut by_stem: BTreeMap<&'a str, Vec<(&'a str, &'a Vec<u8>)>> = BTreeMap::new();
+        for (name, body) in in_folder {
+            by_stem
+                .entry(strip_json_suffix(name))
+                .or_default()
+                .push((name.as_str(), *body));
+        }
+        Self { by_stem }
+    }
+
+    /// Add every sidecar whose stem starts with `prefix` to `out`.
+    fn starting_with(&self, prefix: &str, out: &mut BTreeMap<&'a str, &'a Vec<u8>>) {
+        let from = (
+            std::ops::Bound::Included(prefix),
+            std::ops::Bound::Unbounded,
+        );
+        for (stem, sidecars) in self.by_stem.range::<str, _>(from) {
+            if !stem.starts_with(prefix) {
+                break;
+            }
+            out.extend(sidecars.iter().copied());
+        }
+    }
+
+    /// Add every sidecar whose stem is `head`, or starts with `head` and a `.`:
+    /// those that have `head` as a boundary ([`suffix_boundaries`]).
+    fn bounded_by(&self, head: &str, out: &mut BTreeMap<&'a str, &'a Vec<u8>>) {
+        if let Some(sidecars) = self.by_stem.get(head) {
+            out.extend(sidecars.iter().copied());
+        }
+        self.starting_with(&format!("{head}."), out);
+    }
+
+    /// Every sidecar [`sidecar_rank`] could match `file_name` to, by name. A
+    /// superset: each one is still ranked.
+    fn candidates(&self, file_name: &str) -> BTreeMap<&'a str, &'a Vec<u8>> {
+        let mut out = BTreeMap::new();
+        // Rules 0 and 2: the stem starts with the name, or with its swapped form.
+        self.starting_with(file_name, &mut out);
+        if let Some(swapped) = swap_duplicate_marker(file_name) {
+            self.starting_with(&swapped, &mut out);
+        }
+        // Rule 1: the stem of `A(N).B` starts with `A.B(N)`, so with `A.`.
+        for (paren, _) in file_name.match_indices('(') {
+            self.starting_with(&format!("{}.", &file_name[..paren]), &mut out);
+        }
+        // Rule 3: a boundary of the stem is a prefix of the name.
+        for end in file_name
+            .char_indices()
+            .map(|(index, _)| index)
+            .skip(1)
+            .chain([file_name.len()])
+        {
+            self.bounded_by(&file_name[..end], &mut out);
+        }
+        // Rule 4: `<original>-<word>.<ext>` has `<original>.<ext>` as a boundary.
+        if let Some((_, extension)) = file_name.rsplit_once('.') {
+            for (dash, _) in file_name.match_indices('-') {
+                self.bounded_by(&format!("{}.{extension}", &file_name[..dash]), &mut out);
+            }
+        }
+        out
+    }
+}
+
+/// Find the sidecar belonging to `file_name` among the JSON files of its folder,
+/// with the rank it matched at.
 ///
 /// Tried in order of confidence: the exact name, the `(N)`-swapped name, an
-/// unknown trailing suffix, then a prefix match for the case where truncation
-/// cut into the photo name itself. The best-ranked candidate in the folder wins.
+/// unknown trailing suffix, a prefix match for the case where truncation cut
+/// into the photo name itself, and last an edited copy's original. The
+/// best-ranked candidate in the folder wins; of equal ranks, the first by
+/// sidecar name.
 fn find_sidecar<'a>(
     file_name: &str,
-    in_folder: &BTreeMap<String, &'a Vec<u8>>,
-) -> Option<&'a Vec<u8>> {
+    index: &SidecarIndex<'a>,
+) -> Option<((u8, usize), &'a Vec<u8>)> {
     let mut best: Option<((u8, usize), &'a Vec<u8>)> = None;
-    for (sidecar_name, body) in in_folder {
+    for (sidecar_name, body) in index.candidates(file_name) {
         let Some(rank) = sidecar_rank(strip_json_suffix(sidecar_name), file_name) else {
             continue;
         };
@@ -645,7 +744,7 @@ fn find_sidecar<'a>(
             best = Some((rank, body));
         }
     }
-    best.map(|(_, body)| body)
+    best
 }
 
 /// How well a sidecar's `.json`-stripped `stem` matches `file_name`, as a sort
@@ -683,9 +782,13 @@ fn sidecar_rank(stem: &str, file_name: &str) -> Option<(u8, usize)> {
     }
     // 3 — truncation ate into the photo name itself, leaving only a prefix of
     // it. Every suffix boundary in the stem is tried, so this holds for a
-    // localized suffix too; the longest surviving prefix wins, because a folder
-    // with `IMG_1.jpg` and `IMG_12.jpg` must not let the shorter stem claim the
-    // longer photo.
+    // localized suffix too; the longest surviving prefix wins.
+    //
+    // Only for a sidecar whose name is as long as Google lets one get: a name
+    // that short of the cap was not cut, so a prefix of it is the name of a
+    // different photo. Without this, `IMG_1.jpg`'s sidecar gave its name and
+    // date to an `IMG_12.jpg` that had none (`docs/BUGS.md` B225).
+    if stem.chars().count() + ".json".len() >= SIDECAR_NAME_CAP - 4 {
         let mut longest: Option<usize> = None;
         for head in suffix_boundaries(stem) {
             if !head.is_empty()
@@ -695,7 +798,28 @@ fn sidecar_rank(stem: &str, file_name: &str) -> Option<(u8, usize)> {
                 longest = Some(head.len());
             }
         }
-    longest.map(|len| (3, usize::MAX - len))
+        if let Some(len) = longest {
+            return Some((3, usize::MAX - len));
+        }
+    }
+    // 4 — an edited copy, `IMG_1-edited.jpg` (the word is localized), which
+    // Google exports without a sidecar of its own next to `IMG_1.jpg`'s.
+    suffix_boundaries(stem)
+        .filter_map(|head| head.rsplit_once('.'))
+        .any(|(original, extension)| is_edited_copy_of(file_name, original, extension))
+        .then_some((EDITED_COPY, 0))
+}
+
+/// Whether `file_name` is `<original>-<word>.<extension>`, the name Google
+/// gives an edited copy of `<original>.<extension>`.
+fn is_edited_copy_of(file_name: &str, original: &str, extension: &str) -> bool {
+    !original.is_empty()
+        && file_name
+            .strip_prefix(original)
+            .and_then(|rest| rest.strip_prefix('-'))
+            .and_then(|rest| rest.strip_suffix(extension))
+            .and_then(|rest| rest.strip_suffix('.'))
+            .is_some_and(|word| !word.is_empty() && word.chars().all(char::is_alphabetic))
 }
 
 /// The stem plus each of its prefixes ending before a `.`, longest first — the
@@ -994,21 +1118,25 @@ mod tests {
 
     #[test]
     fn longest_prefix_wins_when_the_photo_name_itself_was_truncated() {
+        // Both sidecar names are at Google's cap, so both were cut into the
+        // photo name; the longer surviving prefix is the better claim.
+        let short = "Takeout/Google Photos/Photos from 2019/PXL_20190101_120000000.PORTRAIT_ORIGINAL_E.json";
+        let long = "Takeout/Google Photos/Photos from 2019/PXL_20190101_120000000.PORTRAIT_ORIGINAL_EXPO.json";
         let mut sidecars = HashMap::new();
         sidecar(
             &mut sidecars,
-            "Takeout/Google Photos/Photos from 2019/IMG_1.json",
+            short,
             r#"{"photoTakenTime":{"timestamp":"1"}}"#,
         );
         sidecar(
             &mut sidecars,
-            "Takeout/Google Photos/Photos from 2019/IMG_12.json",
+            long,
             r#"{"photoTakenTime":{"timestamp":"2"}}"#,
         );
         let scan = assemble(
             vec![entry(
                 0,
-                "Takeout/Google Photos/Photos from 2019/IMG_12345.jpg",
+                "Takeout/Google Photos/Photos from 2019/PXL_20190101_120000000.PORTRAIT_ORIGINAL_EXPOSURE.jpg",
                 10,
             )],
             &sidecars,
@@ -1017,6 +1145,104 @@ mod tests {
         assert_eq!(scan.photos[0].capture_time, Some(2));
     }
 
+    /// A short sidecar name was not cut, so a prefix of it names another photo:
+    /// `IMG_1.jpg`'s sidecar gave its title and date to `IMG_12.jpg`
+    /// (`docs/BUGS.md` B225).
+    #[test]
+    fn a_photo_without_a_sidecar_does_not_take_a_shorter_named_siblings() {
+        let mut sidecars = HashMap::new();
+        sidecar(
+            &mut sidecars,
+            "Takeout/Google Photos/Photos from 2019/IMG_1.jpg.supplemental-metadata.json",
+            r#"{"title":"IMG_1.jpg","photoTakenTime":{"timestamp":"1"}}"#,
+        );
+        let scan = assemble(
+            vec![
+                entry(0, "Takeout/Google Photos/Photos from 2019/IMG_1.jpg", 10),
+                entry(0, "Takeout/Google Photos/Photos from 2019/IMG_12.jpg", 10),
+            ],
+            &sidecars,
+        );
+
+        assert_eq!(scan.photos[0].capture_time, Some(1));
+        assert_eq!(scan.photos[1].name, "IMG_12.jpg");
+        assert_eq!(scan.photos[1].capture_time, None);
+    }
+
+    /// An edited copy has no sidecar of its own. It takes its original's date,
+    /// but keeps its own name rather than the original's title.
+    #[test]
+    fn an_edited_copy_takes_its_originals_date_and_keeps_its_name() {
+        let mut sidecars = HashMap::new();
+        sidecar(
+            &mut sidecars,
+            "Takeout/Google Fotos/Urlaub/IMG_2.jpg.ergänzende-Metadaten.json",
+            r#"{"title":"Holiday.jpg","photoTakenTime":{"timestamp":"7"}}"#,
+        );
+        let scan = assemble(
+            vec![
+                entry(0, "Takeout/Google Fotos/Urlaub/IMG_2.jpg", 10),
+                entry(0, "Takeout/Google Fotos/Urlaub/IMG_2-bearbeitet.jpg", 10),
+            ],
+            &sidecars,
+        );
+
+        assert_eq!(scan.photos[0].name, "Holiday.jpg");
+        assert_eq!(scan.photos[1].name, "IMG_2-bearbeitet.jpg");
+        assert_eq!(scan.photos[1].capture_time, Some(7));
+    }
+
+    /// The index looks only at the sidecars that can match, and must find the
+    /// same one that ranking every sidecar in the folder finds.
+    #[test]
+    fn the_sidecar_index_finds_what_ranking_every_sidecar_finds() {
+        let long = "A_very_long_holiday_photo_name_from_the_beach_2019";
+        let names = [
+            "IMG_1.jpg".to_string(),
+            "IMG_12.jpg".to_string(),
+            "IMG_1(1).jpg".to_string(),
+            "IMG_1-edited.jpg".to_string(),
+            "IMG_1-bearbeitet.jpg".to_string(),
+            "my.photo(2).jpg".to_string(),
+            "x(1).jpg".to_string(),
+            "Ölbild.png".to_string(),
+            "PXL_20230101_101010.mp4".to_string(),
+            format!("{long}.jpg"),
+            format!("{long}_2.jpg"),
+            "nothing.heic".to_string(),
+        ];
+        let sidecar_names = [
+            "IMG_1.jpg.supplemental-metadata.json".to_string(),
+            "IMG_1.jpg(1).supplemental-metadata.json".to_string(),
+            "IMG_12.jpg.ergänzende-Metadaten.json".to_string(),
+            "my.photo.jpg(2).json".to_string(),
+            "x.jpg(1).json".to_string(),
+            "Ölbild.png.suppl.json".to_string(),
+            "PXL_20230101_101010.mp4.JSON".to_string(),
+            format!("{}.json", &long[..44]),
+            format!("{long}.jp.json"),
+            "IMG.json".to_string(),
+            "unrelated.json".to_string(),
+        ];
+        let bodies: Vec<Vec<u8>> = (0..sidecar_names.len())
+            .map(|i| i.to_string().into_bytes())
+            .collect();
+        let in_folder: BTreeMap<String, &Vec<u8>> =
+            sidecar_names.iter().cloned().zip(bodies.iter()).collect();
+        let index = SidecarIndex::new(&in_folder);
+        for name in &names {
+            let mut every: Option<((u8, usize), &Vec<u8>)> = None;
+            for (sidecar_name, body) in &in_folder {
+                if let Some(rank) = sidecar_rank(strip_json_suffix(sidecar_name), name)
+                    && every.as_ref().is_none_or(|(current, _)| rank < *current)
+                {
+                    every = Some((rank, *body));
+                }
+            }
+            assert_eq!(find_sidecar(name, &index), every, "{name}");
+        }
+    }
+
     #[test]
     fn sidecar_title_replaces_a_mangled_on_disk_name() {
         let mut sidecars = HashMap::new();

crates/pdfs-fuse/src/background.rs

@@ -723,16 +723,24 @@ fn scan_local_once(
     // has seen and stays indeterminate.
     let job = transfers.begin_background_job("Indexing this computer");
     job.detail("Scanning your files");
+    let mut failed = false;
     let walked = localindex::scan(&[home], &excludes, |batch| {
         if let Err(e) = db.local_upsert_batch(generation, &batch) {
             warn!(error = %e, "local index: batch write failed");
+            failed = true;
         }
     });
 
-    // Prune what this scan did not see and rebuild the FTS index over the rest,
-    // even if some batches failed — a partial index still beats none.
+    // Prune what this scan did not see, unless it did not see everything:
+    // a path it never reached, or one whose batch failed to write, is not a
+    // path that is gone (`docs/BUGS.md` B217).
     job.detail("Building the search index");
-    match db.local_finish_scan(generation, now_secs()) {
+    let finished = if failed || walked >= localindex::MAX_ENTRIES {
+        db.local_finish_partial_scan(now_secs())
+    } else {
+        db.local_finish_scan(generation, now_secs())
+    };
+    match finished {
         Ok(indexed) => info!(
             walked,
             indexed,

crates/pdfs-fuse/src/control.rs

@@ -911,10 +911,22 @@ fn handle_control_conn(core: &Core, username: &str, mountpoint: &Path, stream: U
                 ))),
                 Ok((file, len)) => {
                     let photos = core.photos();
+                    // Unless the caller knows better: the photo's own EXIF,
+                    // then the file's modification time, which a copy resets.
+                    let capture_time = capture_time.or_else(|| {
+                        let path = Path::new(&source_path);
+                        pdfs_core::exiftime::capture_time_of(path).or_else(|| {
+                            let modified =
+                                std::fs::metadata(path).and_then(|m| m.modified()).ok()?;
+                            let since = modified.duration_since(std::time::UNIX_EPOCH).ok()?;
+                            Some(since.as_secs() as i64)
+                        })
+                    });
                     let metadata = proton_drive_rs::PhotoUploadMetadata {
                         capture_time,
                         ..Default::default()
                     };
+                    let thumbnails = core.upload_thumbnails(Path::new(&source_path), &name);
                     let guard =
                         core.transfers
                             .begin(name.clone(), "", TransferDirection::Upload, len);
@@ -924,7 +936,7 @@ fn handle_control_conn(core: &Core, username: &str, mountpoint: &Path, stream: U
                         &media_type,
                         reader,
                         len as i64,
-                        Vec::new(),
+                        thumbnails,
                         metadata,
                         false,
                     )) {

crates/pdfs-fuse/src/devices.rs

@@ -105,6 +105,15 @@ pub(crate) fn adopted_device_uid() -> Option<String> {
     (!uid.is_empty()).then_some(uid)
 }
 
+/// The paths no sync root may overlap, with the mountpoint as the config says
+/// now.
+pub(crate) fn sync_root_reserved() -> pdfs_core::syncroot::Reserved {
+    let config = pdfs_core::config::AppDirs::new()
+        .map(|dirs| dirs.load_config())
+        .unwrap_or_default();
+    pdfs_core::syncroot::Reserved::current(&config)
+}
+
 /// Pin (or, with `None`, unpin) the adopted device uid in `config.json`.
 pub(crate) fn set_adopted_device_uid(uid: Option<&str>) -> CoreResult<()> {
     let dirs = pdfs_core::config::AppDirs::new()
@@ -517,18 +526,20 @@ impl Core {
             .map_err(|e| CoreError::internal(format!("canonicalize {}: {e}", local.display())))?;
         let local_str = local.to_string_lossy().to_string();
 
-        // Reject duplicates up front for a clear error (UNIQUE would also catch it).
-        if self
+        // `/`, the home folder, the mount, this app's own data, and a folder
+        // inside or around another root are refused (`syncroot::problem`). A
+        // duplicate is one of those, refused here for a clear error before
+        // the UNIQUE constraint would catch it.
+        let others = self
             .db
             .sync_folder_list()
             .map_err(|e| CoreError::internal(format!("db: {e:?}")))?
             .iter()
-            .any(|f| f.local_path == local_str)
-        {
-            return Err(CoreError::invalid(format!(
-                "{} is already synced",
-                local.display()
-            )));
+            .map(|f| PathBuf::from(&f.local_path))
+            .collect::<Vec<_>>();
+        let reserved = sync_root_reserved();
+        if let Some(problem) = pdfs_core::syncroot::problem(&local, &others, &reserved) {
+            return Err(CoreError::invalid(problem));
         }
 
         let name = local

crates/pdfs-fuse/src/drain.rs

@@ -389,13 +389,7 @@ impl Core {
                 // A name a change of ours is about to free is a wait, not a
                 // failure: the trash or rename holding it lands in moments.
                 let held = waits_for_name(e.as_ref());
-                let backoff = if held {
-                    DRAIN_BACKOFF_MIN
-                } else {
-                    DRAIN_BACKOFF_MIN
-                        .saturating_mul(1u32 << attempts.min(6))
-                        .min(DRAIN_BACKOFF_MAX)
-                };
+                let backoff = drain_backoff(attempts, held, op.id);
                 warn!(uid = %op.uid, attempts, error = %err_str, "pending upload failed; will retry");
                 if let Err(e) = self.db.record_attempt_failure(
                     op.id,
@@ -1118,7 +1112,7 @@ impl Core {
             _ => None,
         };
         let sent = self.create_sent_digests(op.id, current);
-        Ok(adoptable(is_dir, &twin, op.created_at, &sent).then_some(twin.uid))
+        Ok(adoptable(is_dir, &twin, self.first_sent(op), &sent).then_some(twin.uid))
     }
 
     /// Record the name the remote actually gave a node, after a conflict forced
@@ -1513,8 +1507,10 @@ impl Core {
             .as_deref()
             .is_some_and(|sha| holds_bytes(&twin, sha));
         let sent = self.create_sent_digests(op.id, current);
-        Ok(adoptable(op.kind == OP_MKDIR, &twin, op.created_at, &sent)
-            .then_some((twin.uid, holds_blob)))
+        Ok(
+            adoptable(op.kind == OP_MKDIR, &twin, self.first_sent(op), &sent)
+                .then_some((twin.uid, holds_blob)),
+        )
     }
 
     /// The SHA-1s of the bytes queued create `id` may have made its file with:
@@ -1529,6 +1525,22 @@ impl Core {
         sent
     }
 
+    /// When create `op` first went out, which is the earliest a node its lost
+    /// answer left can have been made. An op queued offline may wait for days
+    /// before that; measured from when it was queued, the adoption window let
+    /// it take a node another device made in the meantime. Ops sent before the
+    /// time was recorded fall back to when they were queued.
+    fn first_sent(&self, op: &PendingOp) -> i64 {
+        match self.db.create_first_sent(op.id) {
+            Ok(Some(at)) => at.max(op.created_at),
+            Ok(None) => op.created_at,
+            Err(e) => {
+                warn!(id = op.id, error = %e, "reading when a queued create was sent failed");
+                op.created_at
+            }
+        }
+    }
+
     /// Make one queued `create`/`mkdir` real under a given name, and hand back
     /// the API's own error so the caller can tell a name clash from a failure.
     ///
@@ -1541,7 +1553,7 @@ impl Core {
         name: &str,
     ) -> Result<NodeUid, Box<dyn std::error::Error>> {
         self.db
-            .note_create_target(op.id, &parent.to_string(), name)?;
+            .note_create_target(op.id, &parent.to_string(), name, now_millis())?;
         match op.kind == OP_MKDIR {
             true => Ok(self.block_on_bounded(self.drive.create_folder(
                 parent,
@@ -1586,7 +1598,7 @@ impl Core {
             .begin(name, op.uid.clone(), TransferDirection::Upload, meta.len);
         let reader = CountingReader::new(File::open(blob)?, &guard);
         let uid = self.block_on_within(
-            link::upload_deadline(meta.len),
+            link::upload_deadline(meta.len, self.transfers.upload_cap()),
             self.drive.upload_file_from(
                 parent,
                 name,
@@ -1983,7 +1995,7 @@ impl Core {
                 .begin(&alt, meta.uid.clone(), TransferDirection::Upload, meta.len);
         let reader = CountingReader::new(File::open(blob)?, &guard);
         self.block_on_within(
-            link::upload_deadline(meta.len),
+            link::upload_deadline(meta.len, self.transfers.upload_cap()),
             self.drive.upload_file_from(
                 &parent,
                 &alt,
@@ -2236,7 +2248,7 @@ impl Core {
             .clone()
             .ok_or("pending op has no staged blob")?;
         let blob = PathBuf::from(blob);
-        let meta: StagedWrite = serde_json::from_str(op.meta_json.as_deref().unwrap_or(""))?;
+        let mut meta: StagedWrite = serde_json::from_str(op.meta_json.as_deref().unwrap_or(""))?;
         let uid = parse_node_uid(&meta.uid).ok_or("staged write has an unparseable uid")?;
 
         if let Some(reason) = self.revision_conflict(&uid, &meta, &blob)? {
@@ -2275,6 +2287,22 @@ impl Core {
                 &written,
             )
             .map_err(|e| self.errno_error(e, "gap-fill from base failed"))?;
+            // The blob is whole now. Recorded, so that a retry after a lost
+            // answer can match these bytes against the server's revision
+            // (`revision_conflict`) instead of forking a conflict copy of the
+            // user's own write.
+            meta.complete = true;
+            match serde_json::to_string(&meta) {
+                Ok(json) => {
+                    let path = op.blob_path.as_deref().unwrap_or_default();
+                    if let Err(e) = self.db.update_op_meta_for_blob(op.id, path, &json) {
+                        warn!(%uid, error = %e,
+                              "recording a gap-filled blob as whole failed; \
+                               a lost answer may land it as a conflict copy");
+                    }
+                }
+                Err(e) => warn!(%uid, error = %e, "serializing a gap-filled sidecar failed"),
+            }
         }
 
         let name = self.node_name(&uid);
@@ -2295,7 +2323,7 @@ impl Core {
         let reader = CountingReader::new(File::open(&blob)?, &guard).with_cancel(cancel.flag());
         let started = Instant::now();
         let sent = self.block_on_within(
-            link::upload_deadline(meta.len),
+            link::upload_deadline(meta.len, self.transfers.upload_cap()),
             self.drive
                 .upload_new_revision_from(&uid, reader, meta.len as i64, thumbnails, None),
         );
@@ -2753,24 +2781,43 @@ fn waits_for_name(e: &(dyn std::error::Error + 'static)) -> bool {
     std::iter::successors(Some(e), |e| e.source()).any(|e| e.is::<NameHeld>())
 }
 
+/// How long an op waits after its `attempts`-th failure: doubling from
+/// [`DRAIN_BACKOFF_MIN`] up to [`DRAIN_BACKOFF_MAX`], plus up to a fifth more,
+/// different for each op (`seed`), so that ops that failed together are not
+/// all retried in the same second. One that waits for a name (`held`) waits
+/// the minimum.
+///
+/// The doubling stopped at 2^6, 128 s, so the maximum was never reached.
+fn drain_backoff(attempts: i64, held: bool, seed: i64) -> Duration {
+    if held {
+        return DRAIN_BACKOFF_MIN;
+    }
+    let base = DRAIN_BACKOFF_MIN
+        .saturating_mul(1u32 << attempts.clamp(0, 8))
+        .min(DRAIN_BACKOFF_MAX);
+    // A cheap, stable spread: the same op and attempt always wait the same.
+    let spread = (seed.wrapping_mul(0x9E37_79B9).wrapping_add(attempts) as u64 % 21) as u32;
+    base + base * spread / 100
+}
+
 /// How many attempts an op waits for a rename or a create on the wire to free
 /// the name it wants. Two files swapping names each wait for the other, so the
 /// wait has to end; a conflict name ends it.
 const NAME_HOLD_ATTEMPTS: i64 = 4;
 
-/// How much older than its op a remote node may be and still be the one an
-/// unanswered call made. The op is queued the moment the call gives up, so the
-/// node is at most one call's deadline older; the rest is clock skew between
-/// this machine and Proton.
+/// How much older than its op's first send a remote node may be and still be
+/// the one an unanswered call made. The node is made during that call, so it
+/// is at most one call's deadline older; the rest is clock skew between this
+/// machine and Proton.
 const ADOPT_WINDOW_MS: i64 = 2 * 60 * 1000;
 
 /// Whether `twin`, found holding the name a queued create wants, is the node an
-/// earlier, unanswered attempt at that create made: the same kind, created
-/// around when the op was queued, and for a file still empty, as the mount's
+/// earlier, unanswered attempt at that create made: the same kind, created no
+/// earlier than around when the op was first sent (`first_sent_ms`), and for a file still empty, as the mount's
 /// create leaves it, or holding exactly bytes the op uploaded, whose SHA-1 is
 /// one of `sent`.
-fn adoptable(is_dir: bool, twin: &Node, op_created_ms: i64, sent: &[String]) -> bool {
-    if twin.creation_time.saturating_mul(1000) < op_created_ms - ADOPT_WINDOW_MS {
+fn adoptable(is_dir: bool, twin: &Node, first_sent_ms: i64, sent: &[String]) -> bool {
+    if twin.creation_time.saturating_mul(1000) < first_sent_ms - ADOPT_WINDOW_MS {
         return false;
     }
     match &twin.kind {
@@ -3352,6 +3399,22 @@ mod tests {
         }
     }
 
+    #[test]
+    fn a_failing_op_backs_off_to_the_maximum_with_a_spread() {
+        let at = |attempts| drain_backoff(attempts, false, 7);
+        assert!(at(1) >= DRAIN_BACKOFF_MIN * 2);
+        assert!(at(2) > at(1));
+        // Reached, which the doubling capped at 2^6 never did.
+        assert!(at(8) >= DRAIN_BACKOFF_MAX);
+        assert!(at(30) <= DRAIN_BACKOFF_MAX + DRAIN_BACKOFF_MAX / 5);
+        // Ops that failed together do not all come back together.
+        let waits: std::collections::HashSet<_> =
+            (1..=20).map(|id| drain_backoff(8, false, id)).collect();
+        assert!(waits.len() > 5, "{waits:?}");
+        // A wait for a name stays short however often it repeats.
+        assert_eq!(drain_backoff(30, true, 7), DRAIN_BACKOFF_MIN);
+    }
+
     #[test]
     fn only_a_fresh_empty_twin_of_the_same_kind_is_adopted() {
         // The op was queued at t=1000 s, after a create that got no answer.

crates/pdfs-fuse/src/filesystem.rs

@@ -261,10 +261,13 @@ impl Filesystem for ProtonFs {
         // in-flight (possibly unsaved) content: authored bytes come from the
         // scratch file, untouched bytes from the base.
         //
-        // This path stays on the dispatch loop. `write` runs there too, so
-        // keeping its reads there as well preserves the ordering the write path
-        // has always had between a write and a read of the same handle; a mostly
-        // local read is not worth reasoning about that for.
+        // Answered on the dispatch loop when everything it needs is on this
+        // machine, which keeps the order `write` has with reads of the same
+        // handle. A base range that has to be downloaded goes to a worker
+        // instead, with the handle as it was when the read came in: the kernel
+        // issued the read before any write that comes after it, so that is
+        // the content it asked for. On the loop, the download held every
+        // request of the mount (`docs/BUGS.md` B227).
         let handle = {
             let st = self.core.state();
             st.active_writes.get(&ino.0).map(|h| {
@@ -279,7 +282,21 @@ impl Filesystem for ProtonFs {
             })
         };
         if let Some((file, len, uid, base_mtime, base_size, written)) = handle {
-            match self.core.serve_open_read(
+            match self.core.serve_open_read_local(
+                &file,
+                len,
+                &uid,
+                base_mtime,
+                base_size,
+                &written,
+                offset,
+                size as u64,
+            ) {
+                Ok(Some(bytes)) => reply.data(&bytes),
+                Ok(None) => {
+                    let fs = self.clone();
+                    self.core.workers.run(Lane::Transfer, "read", move || {
+                        match fs.core.serve_open_read(
                             &file,
                             len,
                             &uid,
@@ -292,6 +309,10 @@ impl Filesystem for ProtonFs {
                             Ok(bytes) => reply.data(&bytes),
                             Err(e) => reply.error(e),
                         }
+                    });
+                }
+                Err(e) => reply.error(e),
+            }
             return;
         }
         let (uid, mtime, fsize, provisional, is_video) = {
@@ -556,48 +577,62 @@ impl Filesystem for ProtonFs {
             return;
         }
         let new_end = offset.saturating_add(length);
-        let keep_size = (mode & 1) != 0; // FALLOC_FL_KEEP_SIZE
-
-        let is_punch_hole = (mode & 0x02) != 0; // FALLOC_FL_PUNCH_HOLE
-
-        let res = {
+        // Only the modes whose effect on the scratch file this handle can
+        // record. Anything else went through to the scratch file untracked:
+        // a zeroed range was refilled from the base at commit, and a collapse
+        // or insert shifted bytes that `len` and `written` did not follow
+        // (`docs/BUGS.md` B224). `EOPNOTSUPP` is also what makes glibc's
+        // `posix_fallocate` fall back to writing zeros.
+        let Some(kind) = falloc_kind(mode) else {
+            reply.error(Errno::EOPNOTSUPP);
+            return;
+        };
+        let file = {
+            let st = self.core.state();
+            match st.handles.get(&_fh.0).and_then(|i| st.active_writes.get(i)) {
+                Some(aw) => aw.file.clone(),
+                None => {
+                    reply.error(if st.entries.contains_key(&ino.0) {
+                        Errno::EBADF
+                    } else {
+                        Errno::ENOENT
+                    });
+                    return;
+                }
+            }
+        };
+        // The syscall can take a while on a large range; the state lock is
+        // not held across it, as `write` does not hold it across its I/O.
+        let ret = {
+            use std::os::unix::io::AsRawFd;
+            unsafe { libc::fallocate(file.as_raw_fd(), mode, offset as i64, length as i64) }
+        };
+        let res = if ret != 0 {
+            Err(Errno::from(std::io::Error::last_os_error()))
+        } else {
             let mut st = self.core.state();
-            match st
+            if let Some(aw) = st
                 .handles
                 .get(&_fh.0)
                 .copied()
                 .and_then(|i| st.active_writes.get_mut(&i))
             {
-                Some(aw) => {
-                    use std::os::unix::io::AsRawFd;
-                    let fd = aw.file.as_raw_fd();
-                    let ret = unsafe { libc::fallocate(fd, mode, offset as i64, length as i64) };
-                    if ret == 0 {
-                        if is_punch_hole {
-                            // A punched range reads as zero. Mark it authored so
-                            // queue_revision does not refill it from the remote
-                            // baseline and silently undo the hole at commit.
-                            aw.written.add(offset, new_end.min(aw.len));
+                let len = aw.len;
+                let (authored, grown) = kind.effect(offset, new_end, len);
+                if let Some((from, to)) = authored {
+                    // Zeroed or punched bytes read as zero. Marked authored so
+                    // queue_revision does not refill them from the remote
+                    // baseline and silently undo them at commit.
+                    aw.written.add(from, to);
                     aw.dirty = true;
-                        } else if !keep_size && new_end > aw.len {
-                            aw.written.add(aw.len, new_end);
-                            aw.len = new_end;
+                }
+                if let Some(end) = grown {
+                    aw.len = end;
                     aw.dirty = true;
-                            st.set_size(ino.0, new_end);
+                    st.set_size(ino.0, end);
+                }
             }
             Ok(())
-                    } else {
-                        Err(Errno::EIO)
-                    }
-                }
-                None => {
-                    if st.entries.contains_key(&ino.0) {
-                        Err(Errno::EBADF)
-                    } else {
-                        Err(Errno::ENOENT)
-                    }
-                }
-            }
         };
 
         match res {
@@ -606,18 +641,47 @@ impl Filesystem for ProtonFs {
         }
     }
 
-    /// `close(2)` calls flush before release. The upload is queued in `release`
-    /// and performed in the background, so there is nothing
-    /// to push here — the written bytes are already in the scratch file.
+    /// `close(2)` calls flush before release, and flush is the only one of the
+    /// two whose answer reaches the program: the kernel drops `release`'s. So
+    /// the scratch file of a handle with writes on it is synced here, on a
+    /// worker, and a full disk or a failing one is what `close` returns.
+    ///
+    /// Before, flush answered `ok` at once and `release` synced the file, so an
+    /// `ENOSPC` that delayed allocation held back until then was reported to
+    /// nobody, and the program took the save as done (`docs/BUGS.md` B222).
+    /// It also means `release`, which stays on the dispatch loop for ordering,
+    /// finds the pages already on disk instead of writing back a whole file
+    /// while every other request on the mount waits.
     fn flush(
         &self,
         _req: &Request,
         _ino: INodeNo,
-        _fh: FileHandle,
+        fh: FileHandle,
         _lock_owner: LockOwner,
         reply: ReplyEmpty,
     ) {
+        let file = {
+            let st = self.core.state();
+            st.handles
+                .get(&fh.0)
+                .and_then(|ino| st.active_writes.get(ino))
+                .filter(|aw| aw.dirty)
+                .map(|aw| aw.file.clone())
+        };
+        let Some(file) = file else {
             reply.ok();
+            return;
+        };
+        let fs = self.clone();
+        self.core
+            .workers
+            .run(Lane::Transfer, "flush", move || match file.sync_data() {
+                Ok(()) => reply.ok(),
+                Err(e) => {
+                    error!(fh = fh.0, error = %e, "flush of scratch file failed");
+                    reply.error(fs.scratch_sync_errno(&e));
+                }
+            });
     }
 
     /// Durability here means the scratch file, not the remote: a caller asking
@@ -1022,6 +1086,52 @@ fn build_listing(st: &State, ino: u64) -> DirListing {
 /// The cookie handed back is the index of the *next* entry, so a resumed call
 /// continues exactly where the last one stopped — which is only true because
 /// the listing behind those indexes is a snapshot (`docs/BUGS.md` B43).
+/// What an `fallocate` mode does to a write handle, for the modes it can
+/// record (`docs/BUGS.md` B224).
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+enum FallocKind {
+    /// Reserve space; past the end it grows the file unless `keep_size`.
+    Allocate { keep_size: bool },
+    /// Deallocate a range inside the file, which then reads as zero.
+    Punch,
+    /// Zero a range; past the end it grows the file unless `keep_size`.
+    Zero { keep_size: bool },
+}
+
+fn falloc_kind(mode: i32) -> Option<FallocKind> {
+    const KEEP: i32 = libc::FALLOC_FL_KEEP_SIZE;
+    const PUNCH: i32 = libc::FALLOC_FL_PUNCH_HOLE;
+    const ZERO: i32 = libc::FALLOC_FL_ZERO_RANGE;
+    match mode {
+        0 => Some(FallocKind::Allocate { keep_size: false }),
+        KEEP => Some(FallocKind::Allocate { keep_size: true }),
+        m if m == PUNCH | KEEP => Some(FallocKind::Punch),
+        ZERO => Some(FallocKind::Zero { keep_size: false }),
+        m if m == ZERO | KEEP => Some(FallocKind::Zero { keep_size: true }),
+        _ => None,
+    }
+}
+
+impl FallocKind {
+    /// For `[offset, end)` on a file `len` bytes long: the range that now
+    /// reads as zero and must count as written, and the new length if it grew.
+    fn effect(self, offset: u64, end: u64, len: u64) -> (Option<(u64, u64)>, Option<u64>) {
+        let grow = |keep_size: bool| (!keep_size && end > len).then_some(end);
+        let zeroed = |to: u64| (offset < to).then_some((offset, to));
+        match self {
+            // Space past the old end reads as zero, and nothing before it moved.
+            Self::Allocate { keep_size } => {
+                (grow(keep_size).map(|end| (len, end)), grow(keep_size))
+            }
+            Self::Punch => (zeroed(end.min(len)), None),
+            Self::Zero { keep_size } => {
+                let to = if keep_size { end.min(len) } else { end };
+                (zeroed(to), grow(keep_size))
+            }
+        }
+    }
+}
+
 fn reply_listing(listing: &DirListing, offset: u64, root: u64, mut reply: ReplyDirectory) {
     for (i, (ino, is_dir, name)) in listing.iter().enumerate().skip(offset as usize) {
         let ft = if *is_dir {
@@ -1435,6 +1545,20 @@ impl ProtonFs {
     }
 
     /// The body of [`Filesystem::fsync`], run off the dispatch loop.
+    /// The errno to give a program for a failed sync of a scratch file.
+    /// Delayed allocation means a full disk usually surfaces at the sync
+    /// rather than at `write(2)`, and `ENOSPC` is what a program checks for.
+    fn scratch_sync_errno(&self, e: &std::io::Error) -> Errno {
+        match e.raw_os_error() {
+            Some(libc::ENOSPC) => {
+                self.core.cache.emergency_evict();
+                Errno::ENOSPC
+            }
+            Some(libc::EDQUOT) => Errno::EDQUOT,
+            _ => Errno::EIO,
+        }
+    }
+
     fn serve_fsync(&self, fh: FileHandle, reply: ReplyEmpty) {
         // Everything the durability sidecar needs, copied out so no lock is held
         // across the sync.
@@ -1455,22 +1579,18 @@ impl ProtonFs {
                 )
             })
         };
+        // A handle opened for reading has nothing of its own to make durable,
+        // and POSIX allows `fsync` on it; `EBADF` failed `sync FILE` and
+        // backup tools that sync what they read (`docs/BUGS.md` B222).
         let Some((f, path, uid, dirty, written, len, base_size, base_mtime, base_revision_id)) =
             handle
         else {
-            reply.error(Errno::EBADF);
+            reply.ok();
             return;
         };
         if let Err(e) = f.sync_all() {
             error!(fh = fh.0, error = %e, "fsync of scratch file failed");
-            // Delayed allocation means a full disk usually surfaces here rather
-            // than at `write(2)`; `ENOSPC` is what an application checks for.
-            if e.raw_os_error() == Some(libc::ENOSPC) {
-                self.core.cache.emergency_evict();
-                reply.error(Errno::ENOSPC);
-            } else {
-                reply.error(Errno::EIO);
-            }
+            reply.error(self.scratch_sync_errno(&e));
             return;
         }
         // A clean handle has nothing on it that the remote does not already
@@ -1717,9 +1837,7 @@ impl ProtonFs {
         // empty, which it is, so reads stay offline-clean across a restart too.
         if local {
             st.children.insert(ino, Vec::new());
-            if let Err(e) = self.core.db.set_listed(&uid, true) {
-                warn!(%uid, error = %e, "db set_listed(true) failed for local folder");
-            }
+            st.record_listed(uid);
         }
         let entry = st.entries.get(&ino).unwrap();
         let attr = self.attr(ino, &entry.node, entry.access);
@@ -2337,3 +2455,60 @@ impl ProtonFs {
         }
     }
 }
+
+#[cfg(test)]
+mod falloc_tests {
+    use super::*;
+
+    #[test]
+    fn only_the_modes_a_handle_can_record_are_accepted() {
+        let keep = libc::FALLOC_FL_KEEP_SIZE;
+        assert_eq!(
+            falloc_kind(0),
+            Some(FallocKind::Allocate { keep_size: false })
+        );
+        assert_eq!(
+            falloc_kind(keep),
+            Some(FallocKind::Allocate { keep_size: true })
+        );
+        assert_eq!(
+            falloc_kind(libc::FALLOC_FL_PUNCH_HOLE | keep),
+            Some(FallocKind::Punch)
+        );
+        assert_eq!(
+            falloc_kind(libc::FALLOC_FL_ZERO_RANGE),
+            Some(FallocKind::Zero { keep_size: false })
+        );
+        for mode in [
+            libc::FALLOC_FL_PUNCH_HOLE,
+            libc::FALLOC_FL_COLLAPSE_RANGE,
+            libc::FALLOC_FL_INSERT_RANGE,
+            libc::FALLOC_FL_UNSHARE_RANGE,
+        ] {
+            assert_eq!(falloc_kind(mode), None, "{mode:#x}");
+        }
+    }
+
+    /// A zeroed range was left unwritten, so the commit filled it back in
+    /// from the remote base (`docs/BUGS.md` B224).
+    #[test]
+    fn a_zeroed_or_punched_range_counts_as_written() {
+        let zero = FallocKind::Zero { keep_size: false };
+        assert_eq!(zero.effect(10, 20, 100), (Some((10, 20)), None));
+        assert_eq!(zero.effect(90, 120, 100), (Some((90, 120)), Some(120)));
+        let zero_keep = FallocKind::Zero { keep_size: true };
+        assert_eq!(zero_keep.effect(90, 120, 100), (Some((90, 100)), None));
+        assert_eq!(
+            FallocKind::Punch.effect(90, 120, 100),
+            (Some((90, 100)), None)
+        );
+        assert_eq!(FallocKind::Punch.effect(120, 130, 100), (None, None));
+        let alloc = FallocKind::Allocate { keep_size: false };
+        assert_eq!(alloc.effect(0, 50, 100), (None, None));
+        assert_eq!(alloc.effect(90, 120, 100), (Some((100, 120)), Some(120)));
+        assert_eq!(
+            FallocKind::Allocate { keep_size: true }.effect(90, 120, 100),
+            (None, None)
+        );
+    }
+}

crates/pdfs-fuse/src/lib.rs

@@ -116,6 +116,7 @@ mod upload;
 mod r#virtual;
 mod workers;
 use background::{forget_and_notify, run_event_sync, run_local_index, run_photos_event_sync};
+use link::BATCH_CALL_TIMEOUT;
 pub(crate) use mount::is_stale_mount;
 pub use mount::{MountOptions, MountOutcome, mount};
 use mount::{
@@ -2120,12 +2121,39 @@ impl Core {
         }
     }
 
-    /// Whether `ino`'s listing is already in memory, i.e. whether
-    /// [`Core::ensure_children`] would return without touching the network.
-    /// Lets a handler decide between answering inline and handing off to a
-    /// worker, at the cost of one uncontended map lookup.
+    /// Whether [`Core::ensure_children`] would answer for `ino` without
+    /// touching the network. Lets a handler decide between answering inline
+    /// and handing off to a worker.
+    ///
+    /// A resident listing is not enough on its own. A shared folder's, or the
+    /// Shared with me root's, is fetched again once it is a minute old, and
+    /// that fetch ran on the dispatch loop, so every request on the mount
+    /// waited for Drive to answer (`docs/BUGS.md` B219).
     fn children_cached(&self, ino: u64) -> bool {
-        self.state().children.contains_key(&ino)
+        let (uid, resident) = {
+            let st = self.state();
+            match st.entries.get(&ino) {
+                Some(e) => (e.uid.clone(), st.children.contains_key(&ino)),
+                // `list_children` answers ENOENT without the network.
+                None => return true,
+            }
+        };
+        if !resident {
+            return false;
+        }
+        let freshness = if is_virtual_uid(&uid) {
+            Some(SHARED_WITH_ME_SYNCED_MS.to_string())
+        } else if !self.is_own_or_virtual(&uid) && !is_local_uid(&uid) {
+            Some(Self::shared_folder_freshness_key(&uid))
+        } else {
+            None
+        };
+        freshness.is_none_or(|key| {
+            !listing_needs_refresh(
+                self.online.load(Ordering::Relaxed),
+                self.shared_listing_stale(&key),
+            )
+        })
     }
 
     /// Re-apply the optimistic size of any queued write to `nodes`.
@@ -2293,8 +2321,7 @@ impl Core {
 
         let generation = self.shared_generation.load(Ordering::SeqCst);
         let accepted = accepted_share_provenance(
-            self.rt
-                .block_on(self.client.enumerate_shared_with_me())
+            self.block_on_within(BATCH_CALL_TIMEOUT, self.client.enumerate_shared_with_me())
                 .map_err(|error| {
                     error!(%error, "enumerating shared roots failed");
                     Errno::EIO
@@ -2303,8 +2330,10 @@ impl Core {
         let nodes = if accepted.uids.is_empty() {
             Vec::new()
         } else {
-            self.rt
-                .block_on(self.drive.enumerate_nodes_light(&accepted.uids))
+            self.block_on_within(
+                BATCH_CALL_TIMEOUT,
+                self.drive.enumerate_nodes_light(&accepted.uids),
+            )
             .map_err(|error| {
                 error!(%error, "materializing shared roots failed");
                 Errno::EIO
@@ -2687,6 +2716,7 @@ impl Core {
             return Ok(());
         }
 
+        let preassigned = state::inos_for(&self.db, &filtered_nodes);
         let mut st = self.state();
         // Lost the race? Another thread already populated it.
         if st.children.contains_key(&ino) {
@@ -2708,15 +2738,14 @@ impl Core {
             })
             .map(|n| n.uid.clone())
             .collect();
-        let inos = st.intern_batch(ino, filtered_nodes);
+        let inos = st.intern_batch_with_inos(ino, filtered_nodes, preassigned);
         child_inos.extend(inos);
         st.children.insert(ino, child_inos);
         let root_snapshot = primary_root.then(|| RootListingSnapshot::capture(&st, ino).unwrap());
         // Record the listing as complete so a later restart (or a trimmed hot
-        // cache) can rebuild it from the DB without the API.
-        if let Err(e) = self.db.set_listed(&folder_uid, true) {
-            warn!(%folder_uid, error = %e, "db set_listed(true) failed");
-        }
+        // cache) can rebuild it from the DB without the API. Written with the
+        // children's rows when the lock goes, not under it.
+        st.record_listed(folder_uid.clone());
         drop(st);
         self.flush_access_changes();
         if let Some(snapshot) = root_snapshot {
@@ -2879,7 +2908,8 @@ impl Core {
         let (mut key, mut uids, mut slot) = (key, uids, slot);
         loop {
             for chunk in uids.chunks(SIZE_UPGRADE_CHUNK) {
-                let result = self.rt.block_on(self.drive.enumerate_nodes(chunk));
+                let result =
+                    self.block_on_within(BATCH_CALL_TIMEOUT, self.drive.enumerate_nodes(chunk));
                 self.apply_size_upgrade(key, result);
                 slot.chunk_done();
             }
@@ -4378,9 +4408,15 @@ impl Core {
         if self.thumbnail_misses.lock().remote_contains(&key, mtime) {
             return Ok(None);
         }
+        // A file manager asks for one per file in a folder, on the metadata
+        // workers. Offline, or on a stalled link, each one held a worker for
+        // the SDK's whole retry budget, and every cold lookup, create and
+        // rename on the mount queued behind them (`docs/BUGS.md` B220).
+        if !self.is_online() {
+            return Ok(None);
+        }
         let bytes = self
-            .rt
-            .block_on(self.client.download_thumbnail(&uid, ttype))
+            .block_on_bounded(self.client.download_thumbnail(&uid, ttype))
             .map_err(|e| {
                 warn!(%uid, error = %e, "download thumbnail failed");
                 Errno::EIO
@@ -6129,11 +6165,61 @@ fn is_gone(e: &(dyn std::error::Error + 'static)) -> bool {
 /// (`sync.rs`, `conflict_path`), so the two halves of the product name the same
 /// situation the same way and a user only has to learn it once.
 fn conflict_name(name: &str, stamp: i64) -> String {
+    conflict_name_as(name, conflict_label(), stamp)
+}
+
+/// [`conflict_name`] with the machine's label given.
+fn conflict_name_as(name: &str, label: &str, stamp: i64) -> String {
     let path = Path::new(name);
     let stem = path.file_stem().and_then(|s| s.to_str()).unwrap_or(name);
+    let tag = conflict_tag(label, stamp, 0);
     match path.extension().and_then(|s| s.to_str()) {
-        Some(ext) => format!("{stem} (sync-conflict {stamp}).{ext}"),
-        None => format!("{stem} (sync-conflict {stamp})"),
+        Some(ext) => format!("{stem} (sync-conflict {tag}).{ext}"),
+        None => format!("{stem} (sync-conflict {tag})"),
+    }
+}
+
+/// This machine's name as its conflict copies carry it (`docs/BUGS.md` B251).
+///
+/// Two computers syncing one folder that each keep a copy of the same file in
+/// the same second would otherwise make the same name on Drive, and nobody
+/// could tell which computer a copy came from. Read once, from the hostname.
+fn conflict_label() -> &'static str {
+    static LABEL: OnceLock<String> = OnceLock::new();
+    LABEL.get_or_init(|| conflict_label_of(&this_hostname()))
+}
+
+/// `host` as one token: anything but ASCII letters, digits, `-`, `_` and `.`
+/// becomes `-`, so the label holds no space for `conflict_base_name` to trip
+/// on and no `/` or `)` to break the name.
+fn conflict_label_of(host: &str) -> String {
+    let label: String = host
+        .chars()
+        .take(32)
+        .map(|c| {
+            if c.is_ascii_alphanumeric() || matches!(c, '-' | '_' | '.') {
+                c
+            } else {
+                '-'
+            }
+        })
+        .collect();
+    label.trim_matches('-').to_string()
+}
+
+/// The inside of a conflict copy's marker: `<label> <stamp>`, with `-<n>`
+/// when an earlier copy already holds that name. Without a label it is the
+/// bare stamp that copies had before B251.
+fn conflict_tag(label: &str, stamp: i64, suffix: u32) -> String {
+    let suffix = if suffix == 0 {
+        String::new()
+    } else {
+        format!("-{suffix}")
+    };
+    if label.is_empty() {
+        format!("{stamp}{suffix}")
+    } else {
+        format!("{label} {stamp}{suffix}")
     }
 }
 
@@ -6743,7 +6829,27 @@ fn fuse_name(name: &OsStr) -> Result<String, Errno> {
     name.to_str().map(str::to_owned).ok_or(Errno::EILSEQ)
 }
 
+/// Whether a decrypted remote name can stand as one local path component.
+///
+/// Drive checks names only when a client creates or renames a node, and only
+/// for length, so a name made by another client, or by a server that should
+/// not be trusted, can hold anything. Joined onto a local path, a `/` or a `..`
+/// in it walks out of the folder it belongs to, and the mirror engine would
+/// then write or delete outside the sync root. In the mount, the kernel fails
+/// the whole listing with EIO on a single such name (`docs/BUGS.md` B215).
+pub(crate) fn remote_name_is_safe(name: &str) -> bool {
+    !name.is_empty()
+        && name != "."
+        && name != ".."
+        && name.len() <= 255
+        && !name.contains(['/', '\0'])
+}
+
 fn node_visible(node: &Node, folder_uid: &NodeUid, hidden: &HashSet<NodeUid>) -> bool {
+    if !remote_name_is_safe(&node.name) {
+        warn!(uid = %node.uid, "a remote name cannot be a local file name; leaving it out");
+        return false;
+    }
     !node.trashed && node.uid != *folder_uid && !hidden.contains(&node.uid)
 }
 
@@ -7492,14 +7598,15 @@ mod tests {
     use super::{
         Access, AccessFlags, Errno, HashMap, Intervals, PendingRevision, RootListingSnapshot,
         SELF_CHANGE_TTL_MS, ShareId, SharedWithMeItem, StateRegistry, VirtualRootPlan,
-        accepted_share_provenance, conflict_name, copy_pending_for_truncate, expand_restore,
-        first_seen_in_trash, fuse_name, is_stale_mount, node_visible, note_self_change,
-        off_the_runtime, orphan_past_retention, parse_node_uid, prepare_shared_roots,
-        preserve_on_access_denied, publish_virtual_root_in_listing,
-        reconcile_virtual_root_in_listing, release_can_discard_unlinked,
-        release_must_retain_queued_trash, release_unlinked_entry, rename_needs_queue,
-        require_node_parent_access, require_rename_access, resolve_anywhere_with,
-        shared_with_me_uid, take_self_change, uid_write_authority, virtual_node,
+        accepted_share_provenance, conflict_label, conflict_label_of, conflict_name,
+        conflict_name_as, copy_pending_for_truncate, expand_restore, first_seen_in_trash,
+        fuse_name, is_stale_mount, node_visible, note_self_change, off_the_runtime,
+        orphan_past_retention, parse_node_uid, prepare_shared_roots, preserve_on_access_denied,
+        publish_virtual_root_in_listing, reconcile_virtual_root_in_listing,
+        release_can_discard_unlinked, release_must_retain_queued_trash, release_unlinked_entry,
+        rename_needs_queue, require_node_parent_access, require_rename_access,
+        resolve_anywhere_with, shared_with_me_uid, take_self_change, uid_write_authority,
+        virtual_node,
     };
     use super::{Db, WriteAuthority};
     use std::time::Duration;
@@ -8454,15 +8561,38 @@ mod tests {
     #[test]
     fn conflict_name_keeps_the_extension() {
         assert_eq!(
-            conflict_name("notes.txt", 1700),
-            "notes (sync-conflict 1700).txt"
+            conflict_name_as("notes.txt", "laptop", 1700),
+            "notes (sync-conflict laptop 1700).txt"
         );
-        assert_eq!(conflict_name("README", 42), "README (sync-conflict 42)");
         assert_eq!(
-            conflict_name("archive.tar.gz", 7),
-            "archive.tar (sync-conflict 7).gz",
+            conflict_name_as("README", "laptop", 42),
+            "README (sync-conflict laptop 42)"
+        );
+        assert_eq!(
+            conflict_name_as("archive.tar.gz", "laptop", 7),
+            "archive.tar (sync-conflict laptop 7).gz",
             "only the last extension is one, as everywhere else"
         );
+        assert_eq!(
+            conflict_name_as("notes.txt", "", 1700),
+            "notes (sync-conflict 1700).txt"
+        );
+        assert_eq!(
+            conflict_name("notes.txt", 1700),
+            conflict_name_as("notes.txt", conflict_label(), 1700)
+        );
+    }
+
+    /// A hostname goes into a file name, so it is cut down to one safe token
+    /// (B251).
+    #[test]
+    fn a_hostname_becomes_one_safe_token() {
+        assert_eq!(conflict_label_of("laptop"), "laptop");
+        assert_eq!(conflict_label_of("my-pc.local"), "my-pc.local");
+        assert_eq!(conflict_label_of("Linux device"), "Linux-device");
+        assert_eq!(conflict_label_of("a/b) c"), "a-b--c");
+        assert_eq!(conflict_label_of("  "), "");
+        assert_eq!(conflict_label_of(&"x".repeat(40)).len(), 32);
     }
 
     #[test]
@@ -8654,6 +8784,28 @@ mod tests {
         ));
     }
 
+    #[test]
+    fn a_remote_name_that_is_not_one_path_component_is_left_out() {
+        let folder_uid = NodeUid::new(VolumeId::from("vol"), LinkId::from("folder"));
+        let none = std::collections::HashSet::new();
+        for name in [
+            "a/b",
+            "../../.bashrc",
+            "..",
+            ".",
+            "",
+            "a\0b",
+            &"x".repeat(256),
+        ] {
+            let node = node_helper("child", "folder", name, false);
+            assert!(!node_visible(&node, &folder_uid, &none), "{name:?}");
+        }
+        for name in [".hidden", "a..b", "unicodé-文件", &"x".repeat(255)] {
+            let node = node_helper("child", "folder", name, false);
+            assert!(node_visible(&node, &folder_uid, &none), "{name:?}");
+        }
+    }
+
     #[test]
     fn denied_queue_guard_preserves_accepted_bytes_and_pending_count() {
         use std::cell::Cell;
@@ -9159,6 +9311,32 @@ mod tests {
         assert!(online.contains("self.relist_offline_listings();"));
     }
 
+    #[test]
+    fn a_stale_shared_listing_is_fetched_off_the_dispatch_loop() {
+        // A resident listing that `list_children` would fetch again anyway
+        // must not be answered inline (B219).
+        let cached = function_source(include_str!("lib.rs"), "fn children_cached(");
+        assert!(cached.contains("SHARED_WITH_ME_SYNCED_MS"));
+        assert!(cached.contains("Self::shared_folder_freshness_key(&uid)"));
+        assert!(cached.contains("listing_needs_refresh("));
+        assert!(cached.contains("self.shared_listing_stale(&key)"));
+    }
+
+    #[test]
+    fn a_handler_does_not_wait_out_the_sdk_retry_budget() {
+        // Thumbnails, size upgrades and the share list held mount threads for
+        // minutes on a stalled link (B220).
+        let lib = include_str!("lib.rs");
+        let thumbnail = function_source(lib, "fn thumbnail(");
+        assert_before(thumbnail, "if !self.is_online()", "download_thumbnail");
+        assert!(thumbnail.contains(".block_on_bounded(self.client.download_thumbnail("));
+        let upgrade = function_source(lib, "fn run_size_upgrade(");
+        assert!(upgrade.contains("block_on_within(BATCH_CALL_TIMEOUT"));
+        let shared = function_source(lib, "fn ensure_shared_children(");
+        assert!(shared.contains("block_on_within(BATCH_CALL_TIMEOUT"));
+        assert!(!shared.contains("self.rt"));
+    }
+
     #[test]
     fn a_remote_read_gives_up_at_its_deadline() {
         // The SDK bounds requests, not reads; a stalled link held one `read`

crates/pdfs-fuse/src/link.rs

@@ -29,6 +29,13 @@ use crate::{Core, ONLINE_PROBE_MAX, ONLINE_PROBE_MIN};
 /// keep waiting for; queueing the change is the better answer.
 pub(crate) const INTERACTIVE_CALL_TIMEOUT: Duration = Duration::from_secs(20);
 
+/// How long a mount thread waits on a remote read that answers a batch: a
+/// chunk of file sizes, or the list of shares. Longer than an interactive call,
+/// since its answer grows with the batch, but well short of the SDK's own retry
+/// budget, which held a worker for minutes on a stalled link
+/// (`docs/BUGS.md` B220).
+pub(crate) const BATCH_CALL_TIMEOUT: Duration = Duration::from_secs(60);
+
 /// How long one probe may wait for an answer. A probe is a single small request,
 /// and a probe stuck in the SDK's retry budget would delay noticing the link is
 /// back by as long as it waits.
@@ -112,10 +119,25 @@ pub(crate) fn no_answer(after: Duration) -> ProtonError {
 /// transfer that has stopped moving runs into it.
 const SLOWEST_UPLOAD: u64 = 32 * 1024;
 
+/// How many uploads can share the upload cap at once: one per drain worker
+/// and one per mirror sync task.
+const UPLOAD_SLOTS: u64 = (crate::DRAIN_WORKERS + crate::sync::SYNC_CONCURRENCY) as u64;
+
 /// How long an upload of `len` bytes may take before the link is treated as
 /// down: the budget of a metadata call, plus the bytes at [`SLOWEST_UPLOAD`].
-pub(crate) fn upload_deadline(len: u64) -> Duration {
-    INTERACTIVE_CALL_TIMEOUT + Duration::from_secs(len / SLOWEST_UPLOAD)
+///
+/// An upload cap of `cap` bytes per second (`0` for none) is shared by every
+/// upload running, so each may get as little as its share of it. Below
+/// [`SLOWEST_UPLOAD`] a share counts as the slowest rate instead: measured
+/// against the fixed rate, a large file under a low cap ran out of time on
+/// every attempt, took the mount offline each time, and started over from
+/// its first byte.
+pub(crate) fn upload_deadline(len: u64, cap: u64) -> Duration {
+    let slowest = match cap {
+        0 => SLOWEST_UPLOAD,
+        cap => SLOWEST_UPLOAD.min((cap / UPLOAD_SLOTS).max(1)),
+    };
+    INTERACTIVE_CALL_TIMEOUT + Duration::from_secs(len / slowest)
 }
 
 /// Run a remote call, giving up after [`INTERACTIVE_CALL_TIMEOUT`].
@@ -258,8 +280,9 @@ impl Core {
         self.relist_offline_listings();
         // Anything written while offline is queued and waiting on exactly this,
         // including ops that failed on the way down and are sitting out a
-        // backoff sized for a server that keeps refusing.
-        if let Err(e) = self.db.retry_failed_ops_now(crate::now_millis()) {
+        // backoff sized for a server that keeps refusing. Ops Drive refused
+        // keep theirs: the link was not why.
+        if let Err(e) = self.db.retry_unrefused_ops_now(crate::now_millis()) {
             warn!(error = %e, "moving backed-off ops up after a reconnect failed");
         }
         self.wake_drain();
@@ -403,13 +426,31 @@ mod tests {
 
     #[test]
     fn an_upload_gets_longer_the_bigger_it_is() {
-        assert_eq!(upload_deadline(0), INTERACTIVE_CALL_TIMEOUT);
+        assert_eq!(upload_deadline(0, 0), INTERACTIVE_CALL_TIMEOUT);
         assert_eq!(
-            upload_deadline(1 << 30),
+            upload_deadline(1 << 30, 0),
             INTERACTIVE_CALL_TIMEOUT + Duration::from_secs(32_768)
         );
     }
 
+    #[test]
+    fn an_upload_under_a_low_cap_gets_the_time_its_share_of_the_cap_needs() {
+        // A generous cap leaves the deadline as it was.
+        assert_eq!(
+            upload_deadline(1 << 30, 100 << 20),
+            upload_deadline(1 << 30, 0)
+        );
+        // 512 KiB/s shared by every upload slot is below the slowest rate.
+        let share = (512 << 10) / UPLOAD_SLOTS;
+        assert!(share < SLOWEST_UPLOAD);
+        assert_eq!(
+            upload_deadline(1 << 30, 512 << 10),
+            INTERACTIVE_CALL_TIMEOUT + Duration::from_secs((1 << 30) / share)
+        );
+        // A cap below one byte per slot still gives a finite deadline.
+        assert!(upload_deadline(1 << 20, 1) > upload_deadline(1 << 20, 512 << 10));
+    }
+
     #[test]
     fn a_call_past_its_deadline_reads_as_a_lost_link() {
         let rt = tokio::runtime::Builder::new_current_thread()

crates/pdfs-fuse/src/photos.rs

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

crates/pdfs-fuse/src/profile.rs

@@ -15,6 +15,7 @@ use pdfs_core::control::RestorableFolder;
 use pdfs_core::mounts::MountMode;
 use pdfs_core::profile::{
     PROFILE_DIR_NAME, PROFILE_FILE_NAME, PROFILE_VERSION, Profile, ProfileFolder, ProfilePin,
+    is_profile_file_name, profile_file_name, saved_folder,
 };
 use pdfs_core::{CoreError, CoreResult};
 use proton_drive_rs::proton_sdk::ids::NodeUid;
@@ -66,9 +67,14 @@ impl Core {
         });
     }
 
-    /// Serialize this machine's arrangement and upload it to `profile.json`
-    /// inside the device's `.proton-drive-linux` folder, replacing any existing
-    /// one.
+    /// Serialize this machine's arrangement and upload it to its own
+    /// `profile-<machine id>.json` inside the device's `.proton-drive-linux`
+    /// folder, replacing any existing one.
+    ///
+    /// Each machine writes its own file because several computers may sync
+    /// into one device. They used to share `profile.json`, and each save
+    /// replaced the other computers' folders with its own (B252). That file is
+    /// left as it is, so a client before 3.5.0 still finds it.
     ///
     /// Does nothing when no device is registered: a machine that has never
     /// synced a folder has nothing to describe, and registering a device just to
@@ -85,7 +91,11 @@ impl Core {
             CoreError::internal(format!("bad device root uid: {}", device.root_uid))
         })?;
 
-        let profile = self.build_profile(&device.uid)?;
+        let machine_id = pdfs_core::config::AppDirs::new()
+            .and_then(|dirs| dirs.machine_id())
+            .map_err(|e| CoreError::internal(format!("machine id: {e}")))?;
+        let file_name = profile_file_name(&machine_id);
+        let profile = self.build_profile(&device.uid, &machine_id)?;
         let bytes = profile.to_bytes().map_err(CoreError::internal)?;
         let len = bytes.len() as i64;
 
@@ -97,7 +107,7 @@ impl Core {
         // same name: the profile is a single mutable record, and a folder with
         // `profile.json` and `profile (1).json` in it teaches the restore
         // nothing about which to trust.
-        let existing = self.find_device_child_file(&dir_uid, PROFILE_FILE_NAME)?;
+        let existing = self.find_device_child_file(&dir_uid, &file_name)?;
         match existing {
             Some(uid) => self
                 .rt
@@ -114,7 +124,7 @@ impl Core {
                 self.rt
                     .block_on(self.drive.upload_file_replacing_draft_from(
                         &dir_uid,
-                        PROFILE_FILE_NAME,
+                        &file_name,
                         "application/json",
                         Cursor::new(bytes),
                         len,
@@ -130,7 +140,7 @@ impl Core {
     }
 
     /// Snapshot the local arrangement into a [`Profile`].
-    fn build_profile(&self, device_uid: &str) -> CoreResult<Profile> {
+    fn build_profile(&self, device_uid: &str, machine_id: &str) -> CoreResult<Profile> {
         let folders = self
             .db
             .sync_folder_list()
@@ -162,6 +172,7 @@ impl Core {
             version: PROFILE_VERSION,
             device_uid: device_uid.to_string(),
             hostname: this_hostname(),
+            machine_id: Some(machine_id.to_string()),
             saved_at: now_secs(),
             folders,
             pins,
@@ -197,6 +208,31 @@ impl Core {
             .map(|n| n.uid))
     }
 
+    /// The untrashed files directly under `parent_uid` whose name passes
+    /// `keep`.
+    fn device_child_files(
+        &self,
+        parent_uid: &NodeUid,
+        keep: impl Fn(&str) -> bool,
+    ) -> CoreResult<Vec<NodeUid>> {
+        let uids = self
+            .rt
+            .block_on(self.drive.enumerate_folder_children_node_uids(parent_uid))
+            .map_err(|e| CoreError::from_api(&e, "list device root"))?;
+        if uids.is_empty() {
+            return Ok(Vec::new());
+        }
+        let nodes = self
+            .rt
+            .block_on(self.drive.enumerate_nodes(&uids))
+            .map_err(|e| CoreError::from_api(&e, "resolve device root children"))?;
+        Ok(nodes
+            .into_iter()
+            .filter(|n| !n.is_folder() && !n.trashed && keep(&n.name))
+            .map(|n| n.uid)
+            .collect())
+    }
+
     /// The device's `.proton-drive-linux` folder, creating it if this is the
     /// first save on this device.
     ///
@@ -218,32 +254,43 @@ impl Core {
         Ok(uid)
     }
 
-    /// Download and parse this device's profile, if there is one.
+    /// Download and parse the profiles of every computer that syncs this
+    /// device.
     ///
-    /// Looks in `.proton-drive-linux/` first and falls back to the device root,
-    /// where clients before the B78 fix wrote it. The fallback is read-only: the
-    /// next save writes to the folder, and the legacy document is left alone
-    /// rather than trashed, so an older client on another machine keeps working.
-    fn load_profile(&self, root_uid: &NodeUid) -> CoreResult<Option<Profile>> {
-        let current = match self.find_device_child_folder(root_uid, PROFILE_DIR_NAME)? {
-            Some(dir_uid) => self.find_device_child_file(&dir_uid, PROFILE_FILE_NAME)?,
-            None => None,
+    /// Reads every profile in `.proton-drive-linux/`: one per machine, and the
+    /// shared `profile.json` of clients before 3.5.0. Falls back to the device
+    /// root, where clients before the B78 fix wrote it. The fallback is
+    /// read-only: the next save writes to the folder, and the legacy document
+    /// is left alone rather than trashed, so an older client on another
+    /// machine keeps working. A profile that cannot be read is left out and
+    /// logged; the others still count.
+    fn load_profiles(&self, root_uid: &NodeUid) -> CoreResult<Vec<Profile>> {
+        let mut uids = match self.find_device_child_folder(root_uid, PROFILE_DIR_NAME)? {
+            Some(dir_uid) => self.device_child_files(&dir_uid, is_profile_file_name)?,
+            None => Vec::new(),
         };
-        let uid = match current {
-            Some(uid) => uid,
-            None => match self.find_device_child_file(root_uid, PROFILE_FILE_NAME)? {
-                Some(uid) => {
+        if uids.is_empty() {
+            uids = self.device_child_files(root_uid, |name| name == PROFILE_FILE_NAME)?;
+            if !uids.is_empty() {
                 info!("reading legacy profile from the device root");
-                    uid
             }
-                None => return Ok(None),
-            },
-        };
+        }
+        let mut profiles = Vec::new();
+        for uid in uids {
             let mut buf: Vec<u8> = Vec::new();
-        self.rt
+            let parsed = self
+                .rt
                 .block_on(self.drive.download_file_to(&uid, &mut buf))
-            .map_err(|e| CoreError::from_api(&e, "download profile"))?;
-        Profile::parse(&buf).map(Some).map_err(CoreError::invalid)
+                .map_err(|e| CoreError::from_api(&e, "download profile"))
+                .and_then(|()| Profile::parse(&buf).map_err(CoreError::invalid));
+            match parsed {
+                Ok(profile) => profiles.push(profile),
+                Err(e) => {
+                    warn!(%uid, error = %e.message, "could not read a profile; leaving it out")
+                }
+            }
+        }
+        Ok(profiles)
     }
 
     // ---- restore ----------------------------------------
@@ -265,15 +312,16 @@ impl Core {
             CoreError::internal(format!("bad device root uid: {}", device.root_uid))
         })?;
 
-        let profile = match self.load_profile(&root_uid) {
+        let profiles = match self.load_profiles(&root_uid) {
             Ok(p) => p,
             // A missing or unreadable profile is not fatal: the remote tree
             // alone is enough to offer a restore, just with plainer defaults.
             Err(e) => {
-                warn!(error = %e.message, "could not read profile; proposing defaults");
-                None
+                warn!(error = %e.message, "could not read profiles; proposing defaults");
+                Vec::new()
             }
         };
+        let hostname = this_hostname();
 
         let uids = self
             .rt
@@ -304,11 +352,12 @@ impl Core {
             // offering it as a restorable folder would sync the bookkeeping
             // back onto the machine it describes.
             .filter(|n| n.is_folder() && !n.trashed && n.name != PROFILE_DIR_NAME)
+            // The name becomes a folder under the home folder: one with a `/`
+            // or a `..` in it would put the restore somewhere else.
+            .filter(|n| crate::remote_name_is_safe(&n.name))
             .map(|n| {
                 let uid = n.uid.to_string();
-                let saved = profile
-                    .as_ref()
-                    .and_then(|p| p.folders.iter().find(|f| f.remote_uid == uid));
+                let saved = saved_folder(&profiles, &uid, &hostname);
                 let proposed = saved
                     .map(|f| PathBuf::from(&f.local_path))
                     .filter(|p| path_is_usable_here(p))
@@ -349,23 +398,29 @@ impl Core {
             .sync_folder_list()
             .map_err(|e| CoreError::internal(format!("db: {e:?}")))?;
 
+        let reserved = crate::devices::sync_root_reserved();
+        let mut roots: Vec<PathBuf> = existing
+            .iter()
+            .map(|f| PathBuf::from(&f.local_path))
+            .collect();
         let mut restored = 0usize;
         let mut skipped: Vec<String> = Vec::new();
         for item in items {
-            let local = PathBuf::from(&item.local_path);
-            if !local.is_absolute() {
-                skipped.push(format!("{}: local path must be absolute", item.local_path));
+            // The path is proposed from the profile another machine wrote, and
+            // may hold a folder name from Drive: checked like any new root.
+            let local = match pdfs_core::syncroot::resolve(Path::new(&item.local_path)) {
+                Ok(local) => local,
+                Err(e) => {
+                    skipped.push(format!("{}: {e}", item.local_path));
                     continue;
                 }
+            };
             if existing.iter().any(|f| f.remote_uid == item.remote_uid) {
                 skipped.push(format!("{}: already synced", item.local_path));
                 continue;
             }
-            if existing
-                .iter()
-                .any(|f| Path::new(&f.local_path) == local.as_path())
-            {
-                skipped.push(format!("{}: path already in use", item.local_path));
+            if let Some(problem) = pdfs_core::syncroot::problem(&local, &roots, &reserved) {
+                skipped.push(format!("{}: {problem}", item.local_path));
                 continue;
             }
             if let Err(e) = std::fs::create_dir_all(&local) {
@@ -390,6 +445,7 @@ impl Core {
                 let _ = self.request_sync_folder_mode(id, "ondemand");
             }
             let _ = self.sync_tx.send(sync::SyncMsg::Reconcile(id));
+            roots.push(local);
             restored += 1;
         }
         let _ = self.sync_tx.send(sync::SyncMsg::Rewatch);
@@ -482,7 +538,7 @@ mod tests {
     #[test]
     fn loading_falls_back_to_a_legacy_device_root_profile() {
         let source = include_str!("profile.rs");
-        let load = function_source(source, "fn load_profile(");
+        let load = function_source(source, "fn load_profiles(");
         assert!(load.contains("PROFILE_DIR_NAME"), "prefers the folder");
         assert!(
             load.find("PROFILE_DIR_NAME").unwrap()
@@ -491,6 +547,16 @@ mod tests {
         );
     }
 
+    /// Several computers may share a device, so each saves to a file named
+    /// after its own machine id and never to the shared `profile.json`
+    /// (B252).
+    #[test]
+    fn each_machine_saves_its_own_profile() {
+        let save = function_source(include_str!("profile.rs"), "fn save_profile(");
+        assert!(save.contains("profile_file_name(&machine_id)"));
+        assert!(!save.contains("PROFILE_FILE_NAME"));
+    }
+
     /// The profile folder is the client's own bookkeeping: neither the restore
     /// picker nor `add_sync_folder` may treat it as a user folder.
     #[test]

crates/pdfs-fuse/src/reads.rs

@@ -1070,37 +1070,35 @@ impl Core {
         offset: u64,
         size: u64,
     ) -> Result<Vec<u8>, Errno> {
-        if offset >= len || size == 0 {
-            return Ok(Vec::new());
-        }
-        let end = offset.saturating_add(size).min(len);
-        let mut out = Vec::with_capacity((end - offset) as usize);
-        for (s, e, authored) in written.segments(offset, end) {
-            if authored {
-                let mut buf = vec![0u8; (e - s) as usize];
-                file.read_exact_at(&mut buf, s).map_err(|err| {
-                    warn!(%uid, error = %err, "scratch read failed");
-                    Errno::EIO
+        let read = assemble_open_read(file, len, uid, base_size, written, offset, size, |s, n| {
+            self.read_range(uid, base_mtime, base_size, s, n, true)
+                .map(Some)
         })?;
-                out.extend_from_slice(&buf);
-            } else {
-                let bend = e.min(base_size);
-                if s < bend {
-                    out.extend_from_slice(&self.read_range(
-                        uid,
-                        base_mtime,
-                        base_size,
-                        s,
-                        bend - s,
-                        true,
-                    )?);
+        Ok(read.unwrap_or_default())
     }
-                // Anything past the base is a hole: zero-fill.
-                let zeros = e.saturating_sub(s.max(base_size));
-                out.resize(out.len() + zeros as usize, 0);
-            }
-        }
-        Ok(out)
+
+    /// [`Core::serve_open_read`] from bytes already on this machine only:
+    /// `Ok(None)` the moment a range of the base would have to be downloaded.
+    ///
+    /// The dispatch loop answers a read on a write handle with this, and hands
+    /// it to a worker only when it says `None`. Fetching the base there held
+    /// every request of the mount for as long as the download took, up to the
+    /// read deadline (`docs/BUGS.md` B227).
+    #[allow(clippy::too_many_arguments)]
+    pub(super) fn serve_open_read_local(
+        &self,
+        file: &Arc<File>,
+        len: u64,
+        uid: &NodeUid,
+        base_mtime: i64,
+        base_size: u64,
+        written: &Intervals,
+        offset: u64,
+        size: u64,
+    ) -> Result<Option<Vec<u8>>, Errno> {
+        assemble_open_read(file, len, uid, base_size, written, offset, size, |s, n| {
+            Ok(self.cached_range(uid, base_mtime, base_size, s, n))
+        })
     }
 
     /// The largest amount [`Core::fill_gaps_cached`] will copy out of the local
@@ -1242,6 +1240,49 @@ impl Core {
     }
 }
 
+/// The bytes `[offset, offset + size)` of a file open for writing: authored
+/// ranges from its scratch `file`, the rest from its base through `base`,
+/// and zeros past the base. `Ok(None)` when `base` says it cannot answer.
+#[allow(clippy::too_many_arguments)]
+fn assemble_open_read(
+    file: &File,
+    len: u64,
+    uid: &NodeUid,
+    base_size: u64,
+    written: &Intervals,
+    offset: u64,
+    size: u64,
+    mut base: impl FnMut(u64, u64) -> Result<Option<Vec<u8>>, Errno>,
+) -> Result<Option<Vec<u8>>, Errno> {
+    if offset >= len || size == 0 {
+        return Ok(Some(Vec::new()));
+    }
+    let end = offset.saturating_add(size).min(len);
+    let mut out = Vec::with_capacity((end - offset) as usize);
+    for (s, e, authored) in written.segments(offset, end) {
+        if authored {
+            let mut buf = vec![0u8; (e - s) as usize];
+            file.read_exact_at(&mut buf, s).map_err(|err| {
+                warn!(%uid, error = %err, "scratch read failed");
+                Errno::EIO
+            })?;
+            out.extend_from_slice(&buf);
+        } else {
+            let bend = e.min(base_size);
+            if s < bend {
+                match base(s, bend - s)? {
+                    Some(bytes) => out.extend_from_slice(&bytes),
+                    None => return Ok(None),
+                }
+            }
+            // Anything past the base is a hole: zero-fill.
+            let zeros = e.saturating_sub(s.max(base_size));
+            out.resize(out.len() + zeros as usize, 0);
+        }
+    }
+    Ok(Some(out))
+}
+
 #[cfg(test)]
 mod block_ring_tests {
     use super::*;
@@ -1394,3 +1435,54 @@ mod prefetch_tests {
         assert!(prefetch.streams.lock().len() <= MAX_PREFETCH_STREAMS + 1);
     }
 }
+
+#[cfg(test)]
+mod open_read_tests {
+    use super::*;
+    use proton_drive_rs::proton_sdk::ids::{LinkId, VolumeId};
+
+    fn scratch(bytes: &[u8]) -> (File, PathBuf) {
+        let path = std::env::temp_dir().join(format!(
+            "pdfs-open-read-{}-{}",
+            std::process::id(),
+            std::time::SystemTime::now()
+                .duration_since(std::time::UNIX_EPOCH)
+                .unwrap()
+                .as_nanos()
+        ));
+        let mut file = File::options()
+            .create_new(true)
+            .read(true)
+            .write(true)
+            .open(&path)
+            .unwrap();
+        file.write_all(bytes).unwrap();
+        (file, path)
+    }
+
+    /// The dispatch loop answers from what is on this machine and says so
+    /// when the base would have to be downloaded, for a worker to do it
+    /// (`docs/BUGS.md` B227).
+    #[test]
+    fn a_read_needing_the_base_says_so_instead_of_fetching() {
+        let uid = NodeUid::new(VolumeId::from("v"), LinkId::from("f"));
+        let (file, path) = scratch(b"ABCDEFGH");
+        let mut written = Intervals::default();
+        written.add(0, 4);
+
+        let authored = assemble_open_read(&file, 8, &uid, 8, &written, 0, 4, |_, _| {
+            panic!("an authored range never asks the base")
+        });
+        assert_eq!(authored.unwrap().as_deref(), Some(&b"ABCD"[..]));
+
+        let missing = assemble_open_read(&file, 8, &uid, 8, &written, 2, 6, |_, _| Ok(None));
+        assert_eq!(missing.unwrap(), None);
+
+        let base = assemble_open_read(&file, 10, &uid, 8, &written, 2, 8, |s, n| {
+            assert_eq!((s, n), (4, 4));
+            Ok(Some(b"efgh".to_vec()))
+        });
+        assert_eq!(base.unwrap().as_deref(), Some(&b"CDefgh\0\0"[..]));
+        let _ = std::fs::remove_file(path);
+    }
+}

crates/pdfs-fuse/src/redate.rs

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

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

@@ -1303,6 +1303,44 @@ mod tests {
         db.unwrap()
     }
 
+    #[test]
+    #[ignore = "mounts FUSE: run with `cargo test -p pdfs-fuse sim:: -- --ignored`"]
+    fn close_syncs_a_written_file_and_fsync_accepts_a_read_only_one() {
+        // `close` is answered by flush, which now syncs the scratch file so a
+        // failure reaches the program; `fsync` on a descriptor opened for
+        // reading failed with EBADF (B222).
+        use std::io::{Read, Write};
+        let drive = FakeDrive::new();
+        let dir = scratch("flush-fsync");
+        let daemon = Daemon::start(&dir, drive.client(1, Faults::lan())).unwrap();
+        let path = daemon.mountpoint.join("notes.txt");
+
+        let mut file = std::fs::File::create(&path).unwrap();
+        file.write_all(b"written then closed").unwrap();
+        drop(file);
+        let mut again = std::fs::OpenOptions::new()
+            .append(true)
+            .open(&path)
+            .unwrap();
+        again.write_all(b", twice").unwrap();
+        again.flush().unwrap();
+        drop(again);
+
+        let mut read_only = std::fs::File::open(&path).unwrap();
+        read_only.sync_all().unwrap();
+        let mut text = String::new();
+        read_only.read_to_string(&mut text).unwrap();
+        assert_eq!(text, "written then closed, twice");
+        drop(read_only);
+
+        assert!(wait_until(Duration::from_secs(30), || {
+            daemon.pending().is_ok_and(|items| items.is_empty())
+        }));
+        assert!(drive.lookup("notes.txt").is_some());
+        assert!(matches!(daemon.stop(), Ok(MountOutcome::Shutdown)));
+        let _ = std::fs::remove_dir_all(&dir);
+    }
+
     #[test]
     #[ignore = "mounts FUSE: run with `cargo test -p pdfs-fuse sim:: -- --ignored`"]
     fn a_stop_ends_a_mirror_pass_after_the_uploads_it_is_sending() {
@@ -1363,6 +1401,216 @@ mod tests {
         let _ = std::fs::remove_dir_all(&dir);
     }
 
+    /// A folder `mirrored` on Drive, synced in mirror mode with `dir/local`,
+    /// which holds `files` before the first pass. Returns the daemon, the
+    /// folder's id and the link it uses.
+    fn start_mirror(
+        drive: &Arc<FakeDrive>,
+        dir: &Path,
+        files: &[(&str, &[u8])],
+    ) -> (Daemon, i64, FakeClient) {
+        let daemon = Daemon::start(dir, drive.client(1, Faults::lan())).unwrap();
+        std::fs::create_dir(daemon.mountpoint.join("mirrored")).unwrap();
+        assert!(wait_until(Duration::from_secs(30), || {
+            daemon.pending().is_ok_and(|items| items.is_empty())
+                && drive.lookup("mirrored").is_some()
+        }));
+        let remote = drive.lookup("mirrored").unwrap();
+        assert!(matches!(daemon.stop(), Ok(MountOutcome::Shutdown)));
+        let local = dir.join("local");
+        std::fs::create_dir_all(&local).unwrap();
+        for (name, bytes) in files {
+            std::fs::write(local.join(name), bytes).unwrap();
+        }
+        let folder = reopen(dir)
+            .sync_folder_add(local.to_str().unwrap(), &remote.to_string(), "")
+            .unwrap();
+        let client = drive.client(1, Faults::lan());
+        let daemon = Daemon::start(dir, client.clone()).unwrap();
+        (daemon, folder, client)
+    }
+
+    /// Wait until a pass of the mirror that began after `since` (epoch
+    /// seconds) is over without errors.
+    fn wait_for_pass(daemon: &Daemon, folder: i64, since: i64) -> bool {
+        wait_until(Duration::from_secs(30), || {
+            let Ok(Response::SyncFolders { items }) = daemon.request(&Request::ListSyncFolders)
+            else {
+                return false;
+            };
+            items.iter().any(|f| {
+                f.id == folder && f.state == "idle" && f.progress.is_none() && f.last_sync >= since
+            })
+        })
+    }
+
+    fn conflict_copies(dir: &Path, stem: &str) -> Vec<PathBuf> {
+        let prefix = format!("{stem} (sync-conflict ");
+        std::fs::read_dir(dir)
+            .unwrap()
+            .filter_map(|e| e.ok())
+            .map(|e| e.path())
+            .filter(|p| {
+                p.file_name()
+                    .and_then(|n| n.to_str())
+                    .is_some_and(|n| n.starts_with(&prefix))
+            })
+            .collect()
+    }
+
+    fn on_drive(drive: &FakeDrive, path: &str) -> Option<Vec<u8>> {
+        match drive.tree().get(path) {
+            Some(Entry::File(content)) => Some(content.to_vec()),
+            _ => None,
+        }
+    }
+
+    #[test]
+    #[ignore = "mounts FUSE: run with `cargo test -p pdfs-fuse sim:: -- --ignored`"]
+    fn a_joining_mirror_keeps_a_same_size_different_file_as_a_conflict() {
+        // A computer joining a folder another one syncs found a file of the
+        // same size at the same path and took it for the same file, so the two
+        // went on holding different content (B248). One that is the same is
+        // still taken as it is.
+        let drive = FakeDrive::new();
+        let dir = scratch("join-same-size");
+        let theirs: &[u8] = b"from the other computer";
+        let ours: &[u8] = b"written on this machine";
+        assert_eq!(theirs.len(), ours.len());
+        let daemon = {
+            let daemon = Daemon::start(&dir, drive.client(1, Faults::lan())).unwrap();
+            std::fs::create_dir(daemon.mountpoint.join("mirrored")).unwrap();
+            assert!(wait_until(Duration::from_secs(30), || {
+                daemon.pending().is_ok_and(|items| items.is_empty())
+                    && drive.lookup("mirrored").is_some()
+            }));
+            daemon
+        };
+        drive.device().write("mirrored/notes.txt", theirs);
+        drive.device().write("mirrored/same.txt", b"identical");
+        let remote = drive.lookup("mirrored").unwrap();
+        assert!(matches!(daemon.stop(), Ok(MountOutcome::Shutdown)));
+        let local = dir.join("local");
+        std::fs::create_dir_all(&local).unwrap();
+        std::fs::write(local.join("notes.txt"), ours).unwrap();
+        std::fs::write(local.join("same.txt"), b"identical").unwrap();
+        reopen(&dir)
+            .sync_folder_add(local.to_str().unwrap(), &remote.to_string(), "")
+            .unwrap();
+        let daemon = Daemon::start(&dir, drive.client(1, Faults::lan())).unwrap();
+
+        assert!(wait_until(Duration::from_secs(60), || {
+            conflict_copies(&local, "notes").len() == 1
+                && std::fs::read(local.join("notes.txt")).is_ok_and(|b| b == theirs)
+                && drive
+                    .tree()
+                    .keys()
+                    .any(|k| k.starts_with("mirrored/notes (sync-conflict "))
+        }));
+        let copy = &conflict_copies(&local, "notes")[0];
+        assert_eq!(std::fs::read(copy).unwrap(), ours);
+        assert_eq!(on_drive(&drive, "mirrored/notes.txt").unwrap(), theirs);
+        assert!(conflict_copies(&local, "same").is_empty());
+        assert!(matches!(daemon.stop(), Ok(MountOutcome::Shutdown)));
+        let _ = std::fs::remove_dir_all(&dir);
+    }
+
+    #[test]
+    #[ignore = "mounts FUSE: run with `cargo test -p pdfs-fuse sim:: -- --ignored`"]
+    fn a_mirror_edit_does_not_replace_a_revision_another_computer_made_since() {
+        // A local edit went up as a new revision of whatever Drive held at the
+        // time of the upload, from a plan made before another computer saved
+        // its own edit. Its edit was left only in the version history (B249).
+        let drive = FakeDrive::new();
+        let dir = scratch("mirror-revision-race");
+        let (daemon, folder, client) =
+            start_mirror(&drive, &dir, &[("a.txt", b"one"), ("b.txt", b"two")]);
+        let local = dir.join("local");
+        assert!(wait_until(Duration::from_secs(30), || {
+            drive.lookup("mirrored/a.txt").is_some() && drive.lookup("mirrored/b.txt").is_some()
+        }));
+        assert!(wait_for_pass(&daemon, folder, 0));
+        // The echoes of the first uploads read the files too.
+        std::thread::sleep(Duration::from_secs(2));
+
+        let a = drive.lookup("mirrored/a.txt").unwrap();
+        let check = client.hold_next_read(&a);
+        std::fs::write(local.join("a.txt"), b"edited here").unwrap();
+        assert!(wait_until(Duration::from_secs(30), || check.reached()));
+        drive
+            .device()
+            .write("mirrored/a.txt", b"edited on the other computer");
+        drop(check);
+        assert!(wait_until(Duration::from_secs(30), || {
+            take_logged()
+                .iter()
+                .any(|line| line.contains("changed on Drive since this pass looked"))
+        }));
+        daemon
+            .request(&Request::SyncNow { id: Some(folder) })
+            .unwrap();
+
+        assert!(wait_until(Duration::from_secs(60), || {
+            std::fs::read(local.join("a.txt")).is_ok_and(|b| b == b"edited on the other computer")
+                && conflict_copies(&local, "a").len() == 1
+                && drive
+                    .tree()
+                    .keys()
+                    .any(|k| k.starts_with("mirrored/a (sync-conflict "))
+        }));
+        assert_eq!(
+            std::fs::read(&conflict_copies(&local, "a")[0]).unwrap(),
+            b"edited here"
+        );
+        assert_eq!(
+            on_drive(&drive, "mirrored/a.txt").unwrap(),
+            b"edited on the other computer"
+        );
+        assert!(matches!(daemon.stop(), Ok(MountOutcome::Shutdown)));
+        let _ = std::fs::remove_dir_all(&dir);
+    }
+
+    #[test]
+    #[ignore = "mounts FUSE: run with `cargo test -p pdfs-fuse sim:: -- --ignored`"]
+    fn a_revision_made_during_a_mirror_download_still_arrives() {
+        // The baseline after a download read the node again, and recorded a
+        // revision another computer made while the download ran as synced.
+        // The disk held the older one, and the newer never arrived (B250).
+        let drive = FakeDrive::new();
+        let dir = scratch("mirror-download-race");
+        let (daemon, folder, client) =
+            start_mirror(&drive, &dir, &[("a.txt", b"one"), ("b.txt", b"two")]);
+        let local = dir.join("local");
+        assert!(wait_until(Duration::from_secs(30), || {
+            drive.lookup("mirrored/a.txt").is_some() && drive.lookup("mirrored/b.txt").is_some()
+        }));
+        assert!(wait_for_pass(&daemon, folder, 0));
+
+        let a = drive.lookup("mirrored/a.txt").unwrap();
+        drive.device().write("mirrored/a.txt", b"second");
+        let download = client.hold_next_download(&a);
+        daemon
+            .request(&Request::SyncNow { id: Some(folder) })
+            .unwrap();
+        assert!(wait_until(Duration::from_secs(30), || download.reached()));
+        drive.device().write("mirrored/a.txt", b"thirdd");
+        drop(download);
+        assert!(wait_until(Duration::from_secs(30), || {
+            std::fs::read(local.join("a.txt")).is_ok_and(|b| b == b"second")
+        }));
+        assert!(wait_for_pass(&daemon, folder, 0));
+
+        daemon
+            .request(&Request::SyncNow { id: Some(folder) })
+            .unwrap();
+        assert!(wait_until(Duration::from_secs(30), || {
+            std::fs::read(local.join("a.txt")).is_ok_and(|b| b == b"thirdd")
+        }));
+        assert!(conflict_copies(&local, "a").is_empty());
+        assert!(matches!(daemon.stop(), Ok(MountOutcome::Shutdown)));
+        let _ = std::fs::remove_dir_all(&dir);
+    }
+
     #[test]
     #[ignore = "mounts FUSE: run with `cargo test -p pdfs-fuse sim:: -- --ignored`"]
     fn a_file_removed_with_its_folder_while_uploading_stays_removed() {

crates/pdfs-fuse/src/state.rs

@@ -212,6 +212,31 @@ pub(crate) fn lid_ino(lid: i64) -> u64 {
     lid.unsigned_abs() + crate::ROOT_INO
 }
 
+/// The inodes of the stored nodes among `nodes`, from their local ids, for
+/// [`State::intern_batch_with_inos`]. Called before the state lock is taken;
+/// a node that already has a row keeps its id. Empty when the database fails,
+/// which leaves the allocation to the lock holder, as before.
+pub(crate) fn inos_for(db: &Db, nodes: &[Node]) -> HashMap<NodeUid, u64> {
+    let stored: Vec<&Node> = nodes
+        .iter()
+        .filter(|node| !crate::r#virtual::is_virtual_uid(&node.uid))
+        .collect();
+    if stored.is_empty() {
+        return HashMap::new();
+    }
+    match db.lids_for(&stored) {
+        Ok(lids) => stored
+            .iter()
+            .zip(lids)
+            .map(|(node, lid)| (node.uid.clone(), lid_ino(lid)))
+            .collect(),
+        Err(error) => {
+            warn!(%error, "no local ids before the listing; allocating them under the lock");
+            HashMap::new()
+        }
+    }
+}
+
 /// The local id of the node at inode `ino`, the inverse of [`lid_ino`]:
 /// `None` for the root and a fallback inode.
 pub(crate) fn ino_lid(ino: u64) -> Option<i64> {
@@ -1074,20 +1099,34 @@ impl State {
     ///
     /// This is what keeps `ls` on a large folder quick: one commit for the
     /// listing, rather than one autocommit — and one fsync — per child.
-    pub(crate) fn intern_batch(&mut self, parent: u64, mut nodes: Vec<Node>) -> Vec<u64> {
+    #[cfg(test)]
+    pub(crate) fn intern_batch(&mut self, parent: u64, nodes: Vec<Node>) -> Vec<u64> {
+        self.intern_batch_with_inos(parent, nodes, HashMap::new())
+    }
+
+    /// [`State::intern_batch`], with inodes for new entries that the caller
+    /// allocated before it took the lock, from [`inos_for`]. Allocating them
+    /// is a write transaction, and under the lock every inline handler of
+    /// every mount waited for it (`docs/BUGS.md` B221). A node missing from
+    /// `inos` still gets one here.
+    pub(crate) fn intern_batch_with_inos(
+        &mut self,
+        parent: u64,
+        mut nodes: Vec<Node>,
+        mut inos: HashMap<NodeUid, u64>,
+    ) -> Vec<u64> {
         for node in &mut nodes {
             self.keep_revision_mtime(node);
         }
         self.outbox.push(DbWrite::Upsert(nodes.clone()));
         let fresh: Vec<&Node> = nodes
             .iter()
-            .filter(|node| !self.by_uid.contains_key(&node.uid))
+            .filter(|node| !self.by_uid.contains_key(&node.uid) && !inos.contains_key(&node.uid))
             .collect();
-        let mut inos = if fresh.is_empty() {
-            HashMap::new()
-        } else {
-            self.new_inos(&fresh)
-        };
+        if !fresh.is_empty() {
+            let allocated = self.new_inos(&fresh);
+            inos.extend(allocated);
+        }
         nodes
             .into_iter()
             .map(|node| {
@@ -1098,6 +1137,13 @@ impl State {
             .collect()
     }
 
+    /// Record `uid`'s listing as complete once the lock is released, after the
+    /// rows of its children: written the other way round, a crash between the
+    /// two left a folder marked complete with no children to show.
+    pub(crate) fn record_listed(&mut self, uid: NodeUid) {
+        self.outbox.push(DbWrite::SetListed(uid, true));
+    }
+
     /// Check if a directory inode has any child nodes in memory or in the database.
     pub(crate) fn has_children(&self, parent: u64) -> bool {
         // A resident listing is authoritative even when empty. Falling through
@@ -1467,6 +1513,44 @@ mod tests {
         );
     }
 
+    /// A listing's inodes are allocated before the lock is taken, and are the
+    /// ones a node would get under it (`docs/BUGS.md` B221).
+    #[test]
+    fn inodes_allocated_before_the_lock_are_the_ones_the_node_keeps() {
+        let (mut st, _dir) = state();
+        let db = st.db.clone();
+        let listing = vec![
+            node("a", "root", "a.txt", false),
+            node("b", "root", "b.txt", false),
+        ];
+        let early = inos_for(&db, &listing);
+        assert_eq!(early.len(), 2);
+        let inos = st.intern_batch_with_inos(0, listing, early.clone());
+        assert_eq!(inos, [early[&uid("a")], early[&uid("b")]]);
+        st.flush_outbox();
+
+        let mut restarted = State::new(db, HashMap::new());
+        assert_eq!(
+            restarted.intern(0, node("b", "root", "b.txt", false)),
+            early[&uid("b")]
+        );
+    }
+
+    /// The listing is recorded complete with its children's rows, when the
+    /// lock goes, never ahead of them.
+    #[test]
+    fn a_listing_is_recorded_complete_after_its_children() {
+        let (mut st, _dir) = state();
+        let root = st.intern(0, node("root", "none", "root", true));
+        st.flush_outbox();
+        st.intern_batch(root, vec![node("a", "root", "a.txt", false)]);
+        st.record_listed(uid("root"));
+        assert!(st.db.children_if_listed(&uid("root")).unwrap().is_none());
+        st.flush_outbox();
+        let kids = st.db.children_if_listed(&uid("root")).unwrap().unwrap();
+        assert_eq!(kids.len(), 1);
+    }
+
     /// Audit A5. Moving a file out of a folder leaves that folder's DB row
     /// claiming a complete listing, so once the hot cache drops it, remote
     /// changes under it stop being seen. `relocate` has to clear both sides.

crates/pdfs-fuse/src/sweep.rs

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

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

@@ -22,7 +22,7 @@ const POLL_INTERVAL: Duration = Duration::from_secs(120);
 /// per-item work is a network round-trip, so a folder with thousands of files is
 /// unusable done one-at-a-time; this bounds concurrency like the bulk-upload
 /// engine does.
-pub(super) const SYNC_CONCURRENCY: usize = 8;
+pub(crate) const SYNC_CONCURRENCY: usize = 8;
 
 /// A message to the sync engine's control thread.
 pub(crate) enum SyncMsg {

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

@@ -83,6 +83,46 @@ pub(super) struct RemoteItem {
     pub(super) is_dir: bool,
     pub(super) mtime: i64,
     pub(super) size: i64,
+    /// The active revision's id. The light walk carries it for every file, so
+    /// it is the signal that tells another client's new revision from a link
+    /// merely re-stamped.
+    pub(super) revision: Option<String>,
+    /// The active revision's content SHA-1, read only for files the walk
+    /// enumerated in full (no baseline, or a moved mtime). `None` is never
+    /// proof of anything.
+    pub(super) sha1: Option<String>,
+}
+
+/// What a pass saw of a remote file: the signature its baseline records once
+/// the file is synced, and what an upload checks Drive still holds before it
+/// supersedes it.
+#[derive(Clone, Debug, PartialEq, Eq)]
+pub(super) struct RemoteSeen {
+    pub(super) mtime: i64,
+    pub(super) size: i64,
+    pub(super) revision: Option<String>,
+}
+
+impl RemoteSeen {
+    /// Whether `node` is still the revision this was taken from. The revision
+    /// id decides it when both sides have one; otherwise the modification time
+    /// and size, which is all a baseline row from before schema 44 holds.
+    pub(super) fn still_current(&self, node: &Node) -> bool {
+        match (&self.revision, crate::node_revision_id(node)) {
+            (Some(seen), Some(now)) => *seen == now,
+            _ => (self.mtime, self.size) == remote_file_sig(node),
+        }
+    }
+}
+
+impl From<&RemoteItem> for RemoteSeen {
+    fn from(item: &RemoteItem) -> Self {
+        Self {
+            mtime: item.mtime,
+            size: item.size,
+            revision: item.revision.clone(),
+        }
+    }
 }
 
 /// The result of a reconcile pass: what it moved, how many paths were kept as
@@ -113,7 +153,7 @@ impl Outcome {
             Applied::Uploaded => self.uploaded += 1,
             Applied::Downloaded => self.downloaded += 1,
             Applied::Conflict => self.conflicts += 1,
-            Applied::Vanished => {}
+            Applied::Vanished | Applied::Adopted => {}
         }
     }
 
@@ -157,10 +197,16 @@ pub(super) enum Pending {
     CreateDir { rel: String, parent: NodeUid },
     /// Upload a brand-new local file into `parent`.
     UploadNew { rel: String, parent: NodeUid },
-    /// Upload a changed local file as a new revision of `uid`.
-    UploadRevision { rel: String, uid: NodeUid },
-    /// Download remote `uid` to the local path, stamping `mtime`. `size` is the
-    /// remote's reported size, used as the transfer's expected total.
+    /// Upload a changed local file as a new revision of `uid`, if Drive still
+    /// holds the revision `seen` describes (B249).
+    UploadRevision {
+        rel: String,
+        uid: NodeUid,
+        seen: RemoteSeen,
+    },
+    /// Download remote `uid` to the local path, stamping `seen.mtime`.
+    /// `seen.size` is the remote's reported size, used as the transfer's
+    /// expected total.
     ///
     /// `local` is what the planning walk saw at this path, or `None` if nothing
     /// was there. A download can run for minutes, so the apply step revalidates
@@ -170,16 +216,26 @@ pub(super) enum Pending {
     Download {
         rel: String,
         uid: NodeUid,
-        mtime: i64,
-        size: i64,
+        seen: RemoteSeen,
         local: Option<LocalSig>,
     },
+    /// First sync of a path present on both sides at the same size, with a
+    /// digest on Drive: hash the local file, and record the baseline if it holds
+    /// the same bytes. A different file of the same size goes the way of
+    /// [`Pending::Conflict`]: two machines syncing one folder must not read as
+    /// in step while they hold different content.
+    Adopt {
+        rel: String,
+        uid: NodeUid,
+        seen: RemoteSeen,
+        sha1: String,
+        local: LocalSig,
+    },
     /// Both sides changed: set the local copy aside, then download remote `uid`.
     Conflict {
         rel: String,
         uid: NodeUid,
-        mtime: i64,
-        size: i64,
+        seen: RemoteSeen,
     },
     /// Both sides changed during a [`push pass`](Core::push_pass): upload the local
     /// copy into `parent` under a conflict name, leaving the remote file as it is.
@@ -194,6 +250,7 @@ impl Pending {
             | Pending::UploadNew { rel, .. }
             | Pending::UploadRevision { rel, .. }
             | Pending::Download { rel, .. }
+            | Pending::Adopt { rel, .. }
             | Pending::Conflict { rel, .. }
             | Pending::PushConflict { rel, .. } => rel,
         }
@@ -206,7 +263,9 @@ impl Pending {
             Pending::UploadNew { .. }
             | Pending::UploadRevision { .. }
             | Pending::PushConflict { .. } => ActivityKind::Upload,
-            Pending::Download { .. } | Pending::Conflict { .. } => ActivityKind::Download,
+            Pending::Download { .. } | Pending::Adopt { .. } | Pending::Conflict { .. } => {
+                ActivityKind::Download
+            }
         }
     }
 
@@ -217,6 +276,7 @@ impl Pending {
             Pending::UploadNew { .. } => "new file",
             Pending::UploadRevision { .. } => "new version",
             Pending::Download { .. } => "from Drive",
+            Pending::Adopt { .. } => "already the same on Drive",
             Pending::Conflict { .. } => "local changes kept as a conflict copy",
             Pending::PushConflict { .. } => "local changes uploaded as a conflict copy",
         }

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

@@ -199,14 +199,160 @@ pub(super) fn guard_local_wipe<B, L>(
     Ok(())
 }
 
+/// Refuse to run a pass whose remote side has vanished in its entirety: the
+/// remote twin of [`guard_local_wipe`].
+///
+/// An empty or truncated remote walk reads to the planner as "Drive deleted
+/// everything", which a pass answers by deleting the local copies. When not
+/// one synced path is left on Drive, a failed listing is far likelier than a
+/// deliberate wipe of the whole folder, so the pass stops instead.
+pub(super) fn guard_remote_wipe<B, R>(
+    baseline: &HashMap<String, B>,
+    remote: &HashMap<String, R>,
+) -> Result<(), String> {
+    if !baseline.is_empty() && baseline.keys().all(|rel| !remote.contains_key(rel)) {
+        return Err(format!(
+            "every one of the {} synced paths is missing on Proton Drive; refusing to \
+             delete them here. If they were deleted on purpose, remove the folder from sync.",
+            baseline.len()
+        ));
+    }
+    Ok(())
+}
+
+/// What a remote walk saw but could not read: a node the SDK left out because
+/// it would not decrypt, or a file whose size could not be read.
+///
+/// A path missing from the walk is read as deleted on Drive, so a pass must
+/// not classify one it only failed to read. Since a node that failed to decrypt
+/// has no name, all a walk can say is that a folder's listing came back short;
+/// every path under that folder that the walk did not return is then left out,
+/// as [`Unscanned`] leaves out what the local scan could not read.
+#[derive(Default)]
+pub(super) struct RemoteGaps {
+    /// Folders whose listing came back with fewer nodes than it named.
+    short: HashSet<String>,
+    /// Paths seen, but whose entry could not be read.
+    unread: HashSet<String>,
+}
+
+impl RemoteGaps {
+    /// The listing of `folder` named nodes that did not come back.
+    pub(super) fn short_listing(&mut self, folder: &str) {
+        self.short.insert(folder.to_string());
+    }
+
+    /// `rel` is on Drive, but the walk could not read what it needs of it.
+    pub(super) fn unread(&mut self, rel: String) {
+        self.unread.insert(rel);
+    }
+
+    pub(super) fn is_empty(&self) -> bool {
+        self.short.is_empty() && self.unread.is_empty()
+    }
+
+    /// Whether `rel` may be missing from `remote` only because the walk could
+    /// not read it. A path the walk returned is never hidden.
+    pub(super) fn hides<R>(
+        &self,
+        rel: &str,
+        remote: &HashMap<String, R>,
+        remote_dirs: &HashMap<String, NodeUid>,
+    ) -> bool {
+        if self.is_empty() || remote.contains_key(rel) {
+            return false;
+        }
+        if self.unread.contains(rel) {
+            return true;
+        }
+        // The deepest folder the walk did list decides: under a short listing,
+        // anything not returned may be one of the nodes it could not read.
+        let mut at = parent_rel(rel);
+        loop {
+            if remote_dirs.contains_key(at) {
+                return self.short.contains(at);
+            }
+            if at.is_empty() {
+                return false;
+            }
+            at = parent_rel(at);
+        }
+    }
+
+    /// The folders to name to the user, sorted.
+    pub(super) fn report(&self) -> Vec<String> {
+        let mut lines: Vec<String> = self
+            .short
+            .iter()
+            .map(|rel| {
+                let shown = if rel.is_empty() { "the folder" } else { rel };
+                format!("{shown} (items on Proton Drive that cannot be read)")
+            })
+            .chain(
+                self.unread
+                    .iter()
+                    .map(|rel| format!("{rel} (cannot be read on Proton Drive)")),
+            )
+            .collect();
+        lines.sort_unstable();
+        lines
+    }
+}
+
+/// Why the remote folder at `rel` must not be trashed although it was deleted
+/// here: something under it is new or changed on Drive since the last sync,
+/// so it is another device's work that this computer has never had.
+///
+/// Trashing the folder would take that work with it, and the next pass would
+/// then delete the copy this pass just downloaded. `None` when everything under
+/// it is exactly what the baseline recorded.
+pub(super) fn remote_subtree_changed(
+    rel: &str,
+    remote: &HashMap<String, RemoteItem>,
+    baseline: &HashMap<String, StoredSyncEntry>,
+) -> Option<String> {
+    let prefix = format!("{rel}/");
+    let mut changed: Vec<&String> = remote
+        .iter()
+        .filter(|(path, _)| path.starts_with(&prefix))
+        .filter(|(path, item)| match baseline.get(*path) {
+            None => true,
+            Some(_) if item.is_dir => false,
+            Some(base) => {
+                remote_sig(base) != Some((item.mtime, item.size))
+                    || revision_moved(Some(base), item.revision.as_deref())
+            }
+        })
+        .map(|(path, _)| path)
+        .collect();
+    changed.sort_unstable();
+    changed
+        .first()
+        .map(|path| format!("{path} is new or changed on Proton Drive"))
+}
+
 /// The size the baseline recorded for `rel`, if its remote signature's mtime
-/// still matches `mtime`.
+/// still matches `mtime` and its revision is still `revision`.
+///
+/// A row without a revision id, while Drive reports one, cannot vouch for the
+/// revision, so the size is read for real. Such a row comes from before
+/// schema 44, or from an upload Drive did not list yet when it was read back.
+/// Another computer's revision in the same second as that upload kept the
+/// modification time, and only the size could show it (B254). The pass then
+/// records the id on the row, so this costs one read per row.
 pub(super) fn unchanged_remote_size(
     baseline: &HashMap<String, StoredSyncEntry>,
     rel: &str,
     mtime: i64,
+    revision: Option<&str>,
 ) -> Option<i64> {
-    match baseline.get(rel).and_then(remote_sig) {
+    let base = baseline.get(rel)?;
+    if revision_moved(Some(base), revision)
+        || (base.remote_revision_id.is_none() && revision.is_some())
+    {
+        return None;
+    }
+    match remote_sig(base) {
         Some((recorded, size)) if recorded == mtime => Some(size),
         _ => None,
     }
@@ -221,6 +367,17 @@ pub(super) fn join_rel(prefix: &str, name: &str) -> String {
     }
 }
 
+/// Whether Drive's active revision `now` is not the one the baseline row was
+/// synced at. Only a revision id on both sides can say so; a row from before
+/// schema 44, or a node read without one, leaves it to the modification time
+/// and size.
+pub(super) fn revision_moved(base: Option<&StoredSyncEntry>, now: Option<&str>) -> bool {
+    match (base.and_then(|b| b.remote_revision_id.as_deref()), now) {
+        (Some(recorded), Some(now)) => recorded != now,
+        _ => false,
+    }
+}
+
 /// The stored remote signature of a baseline row, if it has one.
 pub(super) fn remote_sig(e: &StoredSyncEntry) -> Option<(i64, i64)> {
     match (&e.remote_rev, &e.remote_hash) {
@@ -251,7 +408,8 @@ pub(super) fn rel_to_path(rel: &str) -> PathBuf {
     rel.split('/').collect()
 }
 
-/// The name for a conflict copy of `path`, e.g. `notes (sync-conflict 1700000000).txt`.
+/// The name for a conflict copy of `path`, e.g.
+/// `notes (sync-conflict laptop 1700000000).txt`.
 #[cfg(test)]
 pub(super) fn conflict_path(path: &Path, stamp: i64) -> PathBuf {
     conflict_path_with_suffix(path, stamp, 0)
@@ -260,16 +418,17 @@ pub(super) fn conflict_path(path: &Path, stamp: i64) -> PathBuf {
 /// As [`conflict_path`], with a deterministic suffix used when that name already
 /// exists. This keeps conflict preservation from ever replacing an older copy.
 pub(super) fn conflict_path_with_suffix(path: &Path, stamp: i64, suffix: u32) -> PathBuf {
+    conflict_path_as(path, crate::conflict_label(), stamp, suffix)
+}
+
+/// [`conflict_path_with_suffix`] with the machine's label given.
+pub(super) fn conflict_path_as(path: &Path, label: &str, stamp: i64, suffix: u32) -> PathBuf {
     let stem = path.file_stem().and_then(|s| s.to_str()).unwrap_or("file");
     let ext = path.extension().and_then(|s| s.to_str());
-    let suffix = if suffix == 0 {
-        String::new()
-    } else {
-        format!("-{suffix}")
-    };
+    let tag = crate::conflict_tag(label, stamp, suffix);
     let name = match ext {
-        Some(ext) => format!("{stem} (sync-conflict {stamp}{suffix}).{ext}"),
-        None => format!("{stem} (sync-conflict {stamp}{suffix})"),
+        Some(ext) => format!("{stem} (sync-conflict {tag}).{ext}"),
+        None => format!("{stem} (sync-conflict {tag})"),
     };
     match path.parent() {
         Some(dir) => dir.join(name),
@@ -290,11 +449,14 @@ pub(super) enum FilePlan {
     DeleteLocal,
     DeleteRemote,
     ForgetBaseline,
-    /// First sync of a file that already exists on both sides with identical
-    /// content: record the baseline without transferring anything. Without this,
+    /// First sync of a file that exists on both sides at the same size, with a
+    /// digest on Drive: record the baseline without transferring anything if
+    /// the local file hashes the same, else keep a conflict copy. Without this,
     /// a folder synced for the first time cuts a `(sync-conflict)` copy of every
     /// pre-existing file, because a missing baseline makes both sides read as
-    /// "changed" (see the mass first-sync conflict storm in docs/BUGS.md).
+    /// "changed" (see the mass first-sync conflict storm in docs/BUGS.md). Size
+    /// alone is not enough: a second machine joining the folder would read a
+    /// different file of the same size as in step (B248).
     AdoptBaseline,
 }
 
@@ -313,8 +475,13 @@ pub(super) fn plan_file(
         // left the file the same length, so it was never uploaded.
         baseline.is_none_or(|base| !LocalSig::from(item).same_content(&LocalSig::from(base)))
     });
+    // Another client's new revision shows in its id even when the link's
+    // modification time and the size come out the same.
     let remote_changed = remote.is_some_and(|item| {
-        baseline.is_none_or(|base| remote_sig(base) != Some((item.mtime, item.size)))
+        baseline.is_none_or(|base| {
+            remote_sig(base) != Some((item.mtime, item.size))
+                || revision_moved(Some(base), item.revision.as_deref())
+        })
     });
 
     match (local, remote) {
@@ -324,10 +491,13 @@ pub(super) fn plan_file(
             (false, true) => FilePlan::Download,
             // With a baseline, both-changed is a genuine concurrent edit and must
             // be preserved as a conflict. Without one, "both changed" only means
-            // this is the first sync and there was nothing to compare to: adopt
-            // the baseline when the sizes already match rather than conflict-copy
-            // an already-identical file. Divergent sizes stay a real conflict.
-            (true, true) if baseline.is_none() && l.size == r.size => FilePlan::AdoptBaseline,
+            // this is the first sync and there was nothing to compare to: when the
+            // sizes match and Drive has a digest to compare against, the apply
+            // step hashes the local file before adopting it. Divergent sizes, or
+            // no digest, stay a real conflict: a missing digest proves nothing.
+            (true, true) if baseline.is_none() && l.size == r.size && r.sha1.is_some() => {
+                FilePlan::AdoptBaseline
+            }
             (true, true) => FilePlan::Conflict,
         },
         (Some(_), None) if baseline.is_none() || local_changed => FilePlan::UploadNew,
@@ -359,6 +529,8 @@ mod file_plan_tests {
             is_dir: false,
             mtime,
             size,
+            revision: None,
+            sha1: None,
         }
     }
 
@@ -376,6 +548,7 @@ mod file_plan_tests {
             local_size,
             remote_rev: Some(remote_mtime.to_string()),
             remote_hash: Some(remote_size.to_string()),
+            remote_revision_id: None,
         }
     }
 
@@ -497,12 +670,28 @@ mod file_plan_tests {
     fn first_sync_of_an_identical_file_adopts_the_baseline_not_a_conflict() {
         // No baseline yet (first sync). Same size on both sides is a pre-existing
         // identical file, not a concurrent edit: adopt it rather than cut a
-        // conflict copy of every file in the folder.
+        // conflict copy of every file in the folder. The apply step still
+        // hashes the local file before it records anything.
+        let local = local(10, 40);
+        let remote = RemoteItem {
+            sha1: Some("da39a3ee".into()),
+            ..remote(30, 40)
+        };
+        assert_eq!(
+            plan_file(Some(&local), Some(&remote), None),
+            FilePlan::AdoptBaseline
+        );
+    }
+
+    /// A file on Drive without a digest cannot be compared without a download,
+    /// and the same size is not the same content (B248).
+    #[test]
+    fn first_sync_without_a_remote_digest_is_a_conflict() {
         let local = local(10, 40);
         let remote = remote(30, 40);
         assert_eq!(
             plan_file(Some(&local), Some(&remote), None),
-            FilePlan::AdoptBaseline
+            FilePlan::Conflict
         );
     }
 
@@ -518,6 +707,73 @@ mod file_plan_tests {
         );
     }
 
+    /// Another computer's new revision can leave the modification time and
+    /// the size as they were. The revision id still tells it apart (B249).
+    #[test]
+    fn a_new_remote_revision_is_a_change_even_at_the_same_mtime_and_size() {
+        let mut base = baseline(10, 20, 30, 40);
+        base.remote_revision_id = Some("r1".into());
+        let unedited = local(10, 20);
+        let same = RemoteItem {
+            revision: Some("r1".into()),
+            ..remote(30, 40)
+        };
+        let newer = RemoteItem {
+            revision: Some("r2".into()),
+            ..remote(30, 40)
+        };
+        assert_eq!(
+            plan_file(Some(&unedited), Some(&same), Some(&base)),
+            FilePlan::Unchanged
+        );
+        assert_eq!(
+            plan_file(Some(&unedited), Some(&newer), Some(&base)),
+            FilePlan::Download
+        );
+        let edited = local(11, 20);
+        assert_eq!(
+            plan_file(Some(&edited), Some(&newer), Some(&base)),
+            FilePlan::Conflict
+        );
+
+        // A row from before schema 44 has no id to compare, and a node read
+        // without one says nothing: both fall back to the signature.
+        let old = baseline(10, 20, 30, 40);
+        assert_eq!(
+            plan_file(Some(&unedited), Some(&newer), Some(&old)),
+            FilePlan::Unchanged
+        );
+        assert_eq!(
+            plan_file(Some(&unedited), Some(&remote(30, 40)), Some(&base)),
+            FilePlan::Unchanged
+        );
+    }
+
+    /// The walk reuses the recorded size only while the revision is the one
+    /// the baseline holds.
+    #[test]
+    fn a_moved_revision_makes_the_walk_read_the_size_again() {
+        let mut base = baseline(10, 20, 30, 40);
+        base.remote_revision_id = Some("r1".into());
+        let rows = HashMap::from([("file".to_string(), base)]);
+        assert_eq!(
+            unchanged_remote_size(&rows, "file", 30, Some("r1")),
+            Some(40)
+        );
+        assert_eq!(unchanged_remote_size(&rows, "file", 30, None), Some(40));
+        assert_eq!(unchanged_remote_size(&rows, "file", 30, Some("r2")), None);
+        assert_eq!(unchanged_remote_size(&rows, "file", 31, Some("r1")), None);
+    }
+
+    /// A row without a revision id reuses its size only while Drive gives no
+    /// id either (B254).
+    #[test]
+    fn a_row_without_a_revision_makes_the_walk_read_the_size_again() {
+        let rows = HashMap::from([("file".to_string(), baseline(10, 20, 30, 40))]);
+        assert_eq!(unchanged_remote_size(&rows, "file", 30, Some("r1")), None);
+        assert_eq!(unchanged_remote_size(&rows, "file", 30, None), Some(40));
+    }
+
     #[test]
     fn a_missing_remote_signature_is_treated_as_changed() {
         let local = local(10, 20);
@@ -530,4 +786,96 @@ mod file_plan_tests {
             FilePlan::Download
         );
     }
+
+    fn uid(id: &str) -> NodeUid {
+        NodeUid::new(VolumeId::from("v"), LinkId::from(id))
+    }
+
+    fn folder() -> RemoteItem {
+        RemoteItem {
+            is_dir: true,
+            mtime: 0,
+            size: 0,
+            ..remote(0, 0)
+        }
+    }
+
+    /// An empty or failed remote listing must not read as "Drive deleted
+    /// everything" and delete the local copies.
+    #[test]
+    fn the_remote_wipe_guard_blocks_only_a_total_disappearance() {
+        let base = HashMap::from([("a".to_string(), ()), ("b".to_string(), ())]);
+        let none: HashMap<String, RemoteItem> = HashMap::new();
+        assert!(guard_remote_wipe(&base, &none).is_err());
+        let one = HashMap::from([("b".to_string(), remote(1, 1))]);
+        assert!(guard_remote_wipe(&base, &one).is_ok());
+        let empty: HashMap<String, ()> = HashMap::new();
+        assert!(guard_remote_wipe(&empty, &none).is_ok());
+    }
+
+    /// A node that failed to decrypt has no name, so everything a short
+    /// listing did not return is left out, and nothing else.
+    #[test]
+    fn a_short_remote_listing_hides_what_it_did_not_return() {
+        let remote = HashMap::from([
+            ("docs".to_string(), folder()),
+            ("docs/a.txt".to_string(), remote(1, 1)),
+            ("pics".to_string(), folder()),
+        ]);
+        let dirs = HashMap::from([
+            (String::new(), uid("root")),
+            ("docs".to_string(), uid("docs")),
+            ("pics".to_string(), uid("pics")),
+        ]);
+        let mut gaps = RemoteGaps::default();
+        assert!(!gaps.hides("docs/b.txt", &remote, &dirs));
+        gaps.short_listing("docs");
+        // Returned paths stand; unreturned ones under the short folder hide,
+        // and so does anything under a subfolder it failed to return.
+        assert!(!gaps.hides("docs/a.txt", &remote, &dirs));
+        assert!(gaps.hides("docs/b.txt", &remote, &dirs));
+        assert!(gaps.hides("docs/sub/deep.txt", &remote, &dirs));
+        // A complete sibling listing still reads deletions as deletions.
+        assert!(!gaps.hides("pics/gone.jpg", &remote, &dirs));
+        assert!(!gaps.hides("top.txt", &remote, &dirs));
+        gaps.short_listing("");
+        assert!(gaps.hides("top.txt", &remote, &dirs));
+    }
+
+    #[test]
+    fn a_file_whose_size_could_not_be_read_is_hidden() {
+        let remote: HashMap<String, RemoteItem> = HashMap::new();
+        let dirs = HashMap::from([(String::new(), uid("root"))]);
+        let mut gaps = RemoteGaps::default();
+        gaps.unread("a.txt".to_string());
+        assert!(gaps.hides("a.txt", &remote, &dirs));
+        assert!(!gaps.hides("b.txt", &remote, &dirs));
+        assert_eq!(gaps.report(), ["a.txt (cannot be read on Proton Drive)"]);
+    }
+
+    /// A folder deleted here holds another device's new work on Drive, so
+    /// trashing it would lose that work.
+    #[test]
+    fn a_remote_folder_with_new_or_changed_files_is_not_trashed() {
+        let mut base = HashMap::from([
+            ("x".to_string(), baseline(0, 0, 0, 0)),
+            ("x/old.txt".to_string(), baseline(1, 1, 5, 6)),
+        ]);
+        let mut remote_tree = HashMap::from([
+            ("x".to_string(), folder()),
+            ("x/old.txt".to_string(), remote(5, 6)),
+            ("xy/new.txt".to_string(), remote(1, 1)),
+        ]);
+        // Unchanged under x; a name-prefixed sibling does not count.
+        assert_eq!(remote_subtree_changed("x", &remote_tree, &base), None);
+
+        remote_tree.insert("x/old.txt".to_string(), remote(9, 6));
+        assert!(remote_subtree_changed("x", &remote_tree, &base).is_some());
+
+        remote_tree.insert("x/old.txt".to_string(), remote(5, 6));
+        remote_tree.insert("x/sub".to_string(), folder());
+        assert!(remote_subtree_changed("x", &remote_tree, &base).is_some());
+        base.insert("x/sub".to_string(), baseline(0, 0, 0, 0));
+        assert_eq!(remote_subtree_changed("x", &remote_tree, &base), None);
+    }
 }

crates/pdfs-fuse/src/takeout.rs

@@ -25,7 +25,7 @@ use std::collections::{BTreeMap, HashMap};
 use std::io::Read;
 use std::path::PathBuf;
 use std::sync::Arc;
-use std::sync::atomic::{AtomicBool, Ordering};
+use std::sync::atomic::{AtomicBool, AtomicU64, Ordering};
 
 use pdfs_core::control::{ActivityKind, ImportSummary, TransferDirection};
 use pdfs_core::takeout::{Bucket, TakeoutPhoto, TakeoutScan, scan_archives};
@@ -36,6 +36,7 @@ use sha1::{Digest, Sha1};
 use tracing::{info, warn};
 
 use super::Core;
+use crate::photos::can_make_thumbnail;
 use crate::transfers::CountingReader;
 
 /// The one import this daemon may be running, and how the last one ended.
@@ -136,6 +137,30 @@ fn read_entry<R>(
 }
 
 impl Core {
+    /// Copy archive entry `entry` into the thumbnail staging folder and return
+    /// its path. The caller removes it.
+    fn stage_takeout_entry(
+        &self,
+        archive: &mut zip::ZipArchive<std::io::BufReader<std::fs::File>>,
+        entry: &str,
+    ) -> CoreResult<PathBuf> {
+        static STAGED: AtomicU64 = AtomicU64::new(0);
+        let path = self.cache.raw_thumbnail_staging_dir().join(format!(
+            "takeout-{}-{}",
+            std::process::id(),
+            STAGED.fetch_add(1, Ordering::Relaxed)
+        ));
+        let copied = read_entry(archive, entry, |reader| {
+            let mut file = std::fs::File::create(&path)?;
+            std::io::copy(reader, &mut file)
+        })?;
+        if let Err(e) = copied {
+            let _ = std::fs::remove_file(&path);
+            return Err(CoreError::internal(format!("copy {entry}: {e}")));
+        }
+        Ok(path)
+    }
+
     /// Import Google Photos Takeout archives. Blocking; run on its own thread.
     ///
     /// `cancel` stops the run at the next photo boundary — an upload already on
@@ -321,7 +346,50 @@ impl Core {
                     capture_time: photo.capture_time,
                     ..Default::default()
                 };
-                let uploaded = read_entry(&mut archive, &photo.entry, |reader| {
+                // A thumbnail is made from a file, so a photo that can have one
+                // is copied out of the archive first and uploaded from the copy.
+                // Without one, Proton's apps show a blank tile until they make
+                // their own.
+                let staged = can_make_thumbnail(&photo.name, photo.size)
+                    .then(|| self.stage_takeout_entry(&mut archive, &photo.entry))
+                    .and_then(|staged| {
+                        staged
+                            .inspect_err(|e| {
+                                warn!(name = photo.name, error = %e,
+                                      "copying a takeout photo out failed; uploading it without a thumbnail")
+                            })
+                            .ok()
+                    });
+                let uploaded = match &staged {
+                    Some(path) => {
+                        let thumbnails = self.upload_thumbnails(path, &photo.name);
+                        // No sidecar and no date in the name: the photo's own
+                        // EXIF, before Drive files it under today.
+                        let metadata = PhotoUploadMetadata {
+                            capture_time: metadata
+                                .capture_time
+                                .or_else(|| pdfs_core::exiftime::capture_time_of(path)),
+                            ..metadata
+                        };
+                        std::fs::File::open(path)
+                            .map_err(|e| {
+                                CoreError::internal(format!("open {}: {e}", path.display()))
+                            })
+                            .map(|file| {
+                                let counting =
+                                    CountingReader::new(std::io::BufReader::new(file), &guard);
+                                self.rt.block_on(photos.upload_photo_from(
+                                    &photo.name,
+                                    &photo.media_type,
+                                    counting,
+                                    photo.size as i64,
+                                    thumbnails,
+                                    metadata,
+                                    false,
+                                ))
+                            })
+                    }
+                    None => read_entry(&mut archive, &photo.entry, |reader| {
                         let counting = CountingReader::new(reader, &guard);
                         self.rt.block_on(photos.upload_photo_from(
                             &photo.name,
@@ -332,7 +400,11 @@ impl Core {
                             metadata,
                             false,
                         ))
-                });
+                    }),
+                };
+                if let Some(path) = staged {
+                    let _ = std::fs::remove_file(path);
+                }
                 drop(guard);
                 job.step();
 
@@ -480,7 +552,15 @@ impl Core {
                 let mut state = IMPORT.lock();
                 state.running = false;
                 state.cancel = None;
-                state.last = outcome.as_ref().ok().cloned();
+                // A failed run is reported too: without it, `--wait` read
+                // "no import has run" and exited as if all was well.
+                state.last = Some(match &outcome {
+                    Ok(summary) => summary.clone(),
+                    Err(e) => ImportSummary {
+                        error: Some(e.to_string()),
+                        ..Default::default()
+                    },
+                });
             }
             match outcome {
                 Ok(summary) => {
@@ -545,7 +625,7 @@ pub(crate) fn sha1_of(reader: &mut (dyn Read + Send)) -> CoreResult<String> {
     Ok(hex_lower(&hasher.finalize()))
 }
 
-fn hex_lower(bytes: &[u8]) -> String {
+pub(crate) fn hex_lower(bytes: &[u8]) -> String {
     let mut out = String::with_capacity(bytes.len() * 2);
     for byte in bytes {
         out.push_str(&format!("{byte:02x}"));

crates/pdfs-fuse/src/transfers.rs

@@ -125,6 +125,11 @@ impl TransferRegistry {
         self.download_limit.set(download);
     }
 
+    /// The upload cap in bytes per second, `0` when there is none.
+    pub fn upload_cap(&self) -> u64 {
+        self.upload_limit.rate.load(Ordering::Relaxed)
+    }
+
     fn limit(&self, direction: TransferDirection) -> &RateLimit {
         match direction {
             TransferDirection::Upload => &self.upload_limit,

crates/pdfs-gui/src/activation.rs

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

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

@@ -69,7 +69,7 @@ use gtk4::glib::BoxedAnyObject;
 
 use pdfs_core::auth;
 
-use pdfs_core::config::{AppDirs, FileSort, FilesView};
+use pdfs_core::config::{AppDirs, FileSort, FilesView, WindowState};
 
 use pdfs_core::control::{
     ActivityEntry, ActivityKind, AlbumInfo, BookmarkInfo, ConflictInfo, ConflictKeep, DeviceInfo,
@@ -130,8 +130,12 @@ struct Ui {
     /// the page stack; [`sync_sidebar`] mirrors navigation that starts elsewhere.
     sidebar: gtk4::ListBox,
     /// The sidebar/content split. Collapsed while signed out, so the login page
-    /// owns the whole window and no destination is reachable without a session.
+    /// owns the whole window and no destination is reachable without a session,
+    /// and while the window is [`narrow`](Self::narrow).
     nav: adw::NavigationSplitView,
+    /// The window is too narrow for the sidebar beside a page, so the two take
+    /// turns. Set by the narrow breakpoint; [`refresh`] reads it.
+    narrow: Cell<bool>,
     /// Shared thumbnails for ordinary image files outside the Photos gallery.
     /// One cache and request queue serves Files, search, Shared and Trash, so
     /// the same image is downloaded and decoded only once.
@@ -297,7 +301,10 @@ fn present_window(app: &adw::Application) {
 /// Spawn the tray icon process in the background.
 pub(crate) fn spawn_tray() {
     match Command::new("pdfs-tray").spawn() {
-        Ok(_) => tracing::info!("spawned `pdfs-tray`"),
+        Ok(child) => {
+            tracing::info!("spawned `pdfs-tray`");
+            pdfs_core::opener::reap(child);
+        }
         Err(e) => tracing::error!("failed to spawn `pdfs-tray`: {e}"),
     }
 }
@@ -318,7 +325,9 @@ fn build_window(app: &adw::Application) {
         tracing::warn!("cannot create the app's directories: {e}");
     }
 
-    let stack = adw::ViewStack::new();
+    // Not homogeneous: each page sets the window's minimum width only while it
+    // is shown, so the widest page does not hold every other one wide.
+    let stack = adw::ViewStack::builder().hhomogeneous(false).build();
     let (login_page, login_widgets) = build_login_page();
     let main_widgets = build_main_page();
     let (browser_page, browser_widgets) = build_browser_page();
@@ -336,8 +345,12 @@ fn build_window(app: &adw::Application) {
     login_frame.add_top_bar(&{
         let header = adw::HeaderBar::new();
         header.set_show_title(false);
+        // The split is collapsed while signed out; going "back" would only
+        // uncover a sidebar with nowhere to go.
+        header.set_show_back_button(false);
         header
     });
+    login_frame.add_top_bar(&login_widgets.keyring_banner);
     login_frame.set_content(Some(&login_page));
     stack.add_named(&login_frame, Some("login"));
     stack.add_named(&browser_page, Some("browser"));
@@ -365,6 +378,8 @@ fn build_window(app: &adw::Application) {
         .content(&content_page)
         .min_sidebar_width(200.0)
         .max_sidebar_width(240.0)
+        // A narrow window opens on the page, not the sidebar.
+        .show_content(true)
         .build();
 
     // Toasts float over everything, so a report from a background action reaches
@@ -372,17 +387,22 @@ fn build_window(app: &adw::Application) {
     let toasts = adw::ToastOverlay::new();
     toasts.set_child(Some(&split));
 
+    let (startup_session, keyring_error) = match read_session() {
+        Ok(session) => (session, None),
+        Err(e) => (None, Some(e)),
+    };
     let ui = Rc::new(Ui {
         dirs,
         stack: stack.clone(),
         toasts: toasts.clone(),
         busy: Cell::new(0),
         opening: RefCell::new(HashSet::new()),
-        session: RefCell::new(auth::load().ok()),
+        session: RefCell::new(startup_session),
         unlock_offered: Cell::new(false),
         mounted: RefCell::new(false),
         sidebar: sidebar_list.clone(),
         nav: split.clone(),
+        narrow: Cell::new(false),
         file_thumbs: FileThumbnailState::new(),
         login: login_widgets,
         status: StatusState {
@@ -636,6 +656,9 @@ fn build_window(app: &adw::Application) {
         },
     });
     wire_login(&ui);
+    if let Some(e) = keyring_error {
+        keyring_unreadable(&ui, &e);
+    }
     let ui_status = ui.clone();
     main_widgets
         .status_button
@@ -713,13 +736,18 @@ fn build_window(app: &adw::Application) {
         }
     });
 
+    let saved = ui.dirs.load_config().window.usable();
     let window = adw::ApplicationWindow::builder()
         .application(app)
         .title("Proton Drive")
-        .default_width(980)
-        .default_height(680)
+        .default_width(saved.width)
+        .default_height(saved.height)
+        .maximized(saved.maximized)
+        .width_request(WindowState::MIN_WIDTH)
+        .height_request(WindowState::MIN_HEIGHT)
         .content(&toasts)
         .build();
+    remember_window_state(&ui, app, &window);
     // A wide window docks the details pane beside the files instead of laying it
     // over them.
     let wide = adw::Breakpoint::new(
@@ -727,6 +755,18 @@ fn build_window(app: &adw::Application) {
     );
     wide.add_setter(&ui.browser.split, "collapsed", Some(&false.to_value()));
     window.add_breakpoint(wide);
+    // A narrow window shows the sidebar and the page in turn, so every header
+    // bar keeps room for the window buttons. Signals rather than a setter:
+    // `refresh` decides the collapse while signed out, and would undo one.
+    let narrow = adw::Breakpoint::new(
+        adw::BreakpointCondition::parse("max-width: 760sp").expect("static breakpoint"),
+    );
+    narrow.add_setter(&ui.browser.search, "width-chars", Some(&8.to_value()));
+    let ui_narrow = ui.clone();
+    narrow.connect_apply(move |_| set_narrow(&ui_narrow, true));
+    let ui_wide = ui.clone();
+    narrow.connect_unapply(move |_| set_narrow(&ui_wide, false));
+    window.add_breakpoint(narrow);
     install_shortcuts(&ui, &window);
     install_window_actions(&ui, &window);
     install_launch_actions(&ui, app, &window);
@@ -740,6 +780,51 @@ fn build_window(app: &adw::Application) {
     window.present();
 }
 
+/// Follow the narrow breakpoint. While signed out the login page keeps the
+/// split collapsed whatever the width.
+fn set_narrow(ui: &Ui, narrow: bool) {
+    ui.narrow.set(narrow);
+    if ui.session.borrow().is_some() {
+        ui.nav.set_collapsed(narrow);
+    }
+}
+
+/// Save the window's size when it closes, and when the app quits with the
+/// window still open (Ctrl+Q, the tray's Quit), which never asks it to close.
+fn remember_window_state(ui: &Rc<Ui>, app: &adw::Application, window: &adw::ApplicationWindow) {
+    let ui_close = ui.clone();
+    window.connect_close_request(move |window| {
+        save_window_state(&ui_close, window);
+        glib::Propagation::Proceed
+    });
+    let ui_quit = ui.clone();
+    let window_quit = window.downgrade();
+    app.connect_shutdown(move |_| {
+        if let Some(window) = window_quit.upgrade() {
+            save_window_state(&ui_quit, &window);
+        }
+    });
+}
+
+/// Write the window's unmaximised size and maximised state to the config, if
+/// either changed. Runs as the window goes away, so a failure is only logged.
+fn save_window_state(ui: &Ui, window: &adw::ApplicationWindow) {
+    let (width, height) = window.default_size();
+    let state = WindowState {
+        width,
+        height,
+        maximized: window.is_maximized(),
+    };
+    let mut config = ui.dirs.load_config();
+    if config.window == state {
+        return;
+    }
+    config.window = state;
+    if let Err(e) = ui.dirs.save_config(&config) {
+        tracing::warn!("cannot save the window size: {e}");
+    }
+}
+
 /// Whether `window` is minimised or otherwise out of sight (another workspace,
 /// fully covered), as far as the compositor tells us.
 fn window_hidden(window: &adw::ApplicationWindow) -> bool {
@@ -867,6 +952,18 @@ fn set_busy_spinners(visible: bool) {
     });
 }
 
+/// `row` in a frame that scrolls sideways once the window is too narrow for it,
+/// so a row of labelled buttons never sets the window's minimum width.
+fn scroll_sideways(row: &impl IsA<gtk4::Widget>) -> gtk4::ScrolledWindow {
+    gtk4::ScrolledWindow::builder()
+        .hscrollbar_policy(gtk4::PolicyType::Automatic)
+        .vscrollbar_policy(gtk4::PolicyType::Never)
+        .propagate_natural_width(true)
+        .propagate_natural_height(true)
+        .child(row)
+        .build()
+}
+
 /// A destination page's frame: its own header bar over the page content, the
 /// way GNOME apps lay a split view out. The title sits in the middle with the
 /// busy spinner beside it; the page packs its actions into the returned header
@@ -930,6 +1027,14 @@ fn wire_sidebar(ui: &Rc<Ui>) {
             ui_row.stack.set_visible_child_name(page);
         }
     });
+    // In a narrow window the sidebar covers the page, so picking a row, even
+    // the selected one, has to bring the page forward.
+    let ui_open = ui.clone();
+    ui.sidebar.connect_row_activated(move |_, _| {
+        if ui_open.nav.is_collapsed() {
+            ui_open.nav.set_show_content(true);
+        }
+    });
 }
 
 /// Re-fetch the visible page from the server, bypassing every layer of cache
@@ -1065,8 +1170,17 @@ pub(crate) fn set_sidebar_badge(ui: &Ui, page: &str, count: u64) {
 /// Show a transient toast. Non-blocking by design: an action's outcome is
 /// reported without stealing focus or forcing a click, so the user can keep
 /// working while a slow upload lands.
+///
+/// A toast's title is Pango markup unless told otherwise. Messages carry file
+/// names and daemon errors, and one with a `&` or `<` in it showed as an empty
+/// toast, so every toast here is plain text.
 fn toast(ui: &Rc<Ui>, message: &str) {
-    ui.toasts.add_toast(adw::Toast::new(message));
+    ui.toasts.add_toast(
+        adw::Toast::builder()
+            .title(message)
+            .use_markup(false)
+            .build(),
+    );
 }
 
 /// Show a toast that offers one follow-up action — an Undo, or a way to the page
@@ -1077,6 +1191,7 @@ fn toast(ui: &Rc<Ui>, message: &str) {
 fn toast_action(ui: &Rc<Ui>, message: &str, label: &str, action: impl Fn(&Rc<Ui>) + 'static) {
     let toast = adw::Toast::builder()
         .title(message)
+        .use_markup(false)
         .button_label(label)
         .timeout(8)
         .build();
@@ -1099,7 +1214,11 @@ fn toast_error(ui: &Rc<Ui>, what: &str, detail: &str) {
         gettext_f("{what}: {detail}", &[("what", what), ("detail", detail)])
     };
     tracing::warn!("{message}");
-    let toast = adw::Toast::builder().title(&message).timeout(6).build();
+    let toast = adw::Toast::builder()
+        .title(&message)
+        .use_markup(false)
+        .timeout(6)
+        .build();
     ui.toasts.add_toast(toast);
 }
 
@@ -1699,9 +1818,12 @@ pub(crate) fn flash_copied(button: &gtk4::Button, icon: &'static str) {
 
 /// Open a local path with the handler the user configured — `xdg-open` unless
 /// `open_with` in `config.json` overrides it for this kind of file.
+///
+/// On a thread of its own: telling a folder from a file is a `stat`, and the
+/// path is often in the mount, which may hang.
 fn open_path(path: &str) {
-    let path = Path::new(path);
-    pdfs_core::opener::open_default(path, path.is_dir());
+    let path = PathBuf::from(path);
+    std::thread::spawn(move || pdfs_core::opener::open_default(&path, path.is_dir()));
 }
 
 /// [`open_path`] for a file the daemon materialised into the content cache,

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

@@ -378,7 +378,9 @@ pub(crate) fn activity_status(
 ) {
     ui.activity.status.set_icon_name(Some(icon));
     ui.activity.status.set_title(title);
-    ui.activity.status.set_description(Some(description));
+    ui.activity
+        .status
+        .set_description(Some(&gtk4::glib::markup_escape_text(description)));
     ui.activity.retry.set_visible(retry);
     ui.activity.content.set_visible_child_name("status");
 }

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

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

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

@@ -1,4 +1,4 @@
-use crate::activation::{DriveActivation, drive_activation, mounted_path, mounted_target_rel};
+use crate::activation::{DriveActivation, drive_activation, mounted_path, present_within};
 use crate::*;
 
 pub(crate) struct BrowserState {
@@ -376,7 +376,7 @@ pub(crate) fn build_browser_page() -> (gtk4::Widget, BrowserWidgets) {
     bulk_box.append(&bulk_clear);
     let bulk = gtk4::Revealer::builder()
         .transition_type(gtk4::RevealerTransitionType::SlideDown)
-        .child(&bulk_box)
+        .child(&scroll_sideways(&bulk_box))
         .build();
 
     // The status bar: contextual text (stretch 1), then the icon-size slider.
@@ -500,7 +500,9 @@ pub(crate) fn build_browser_page() -> (gtk4::Widget, BrowserWidgets) {
 pub(crate) fn browser_status(ui: &Rc<Ui>, icon: &str, title: &str, description: &str, retry: bool) {
     ui.browser.status.set_icon_name(Some(icon));
     ui.browser.status.set_title(title);
-    ui.browser.status.set_description(Some(description));
+    ui.browser
+        .status
+        .set_description(Some(&gtk4::glib::markup_escape_text(description)));
     ui.browser.retry.set_visible(retry);
     // Only the empty-folder state offers a way to fill the folder; every other
     // status (loading, offline, error) turns them back off.
@@ -981,9 +983,11 @@ pub(crate) fn background_context_menu(ui: &Rc<Ui>) -> ActionMenu {
 pub(crate) fn open_entry_with(ui: &Rc<Ui>, entry: &DirEntry) {
     let rel = entry_rel(ui, entry);
     let mountpoint = ui.dirs.resolved_mountpoint(&ui.dirs.load_config());
-    let Some(path) = mounted_target_rel(&mountpoint, &rel) else {
+    let ui = ui.clone();
+    glib::spawn_future_local(async move {
+        let Some(path) = present_within(mounted_path(&mountpoint, &rel)).await else {
             toast_error(
-            ui,
+                &ui,
                 &gettext("Couldn't open file"),
                 &gettext("Open With needs the Proton Drive service to be running."),
             );
@@ -991,18 +995,15 @@ pub(crate) fn open_entry_with(ui: &Rc<Ui>, entry: &DirEntry) {
         };
         let launcher = gtk4::FileLauncher::new(Some(&gio::File::for_path(path)));
         launcher.set_always_ask(true);
-    let ui = ui.clone();
-    launcher.launch(
-        ui_window(&ui).as_ref(),
-        gio::Cancellable::NONE,
-        move |result| {
+        let window = ui_window(&ui);
+        launcher.launch(window.as_ref(), gio::Cancellable::NONE, move |result| {
             if let Err(e) = result
                 && !e.matches(gtk4::DialogError::Dismissed)
             {
                 toast_error(&ui, &gettext("Couldn't open file"), &e.to_string());
             }
-        },
-    );
+        });
+    });
 }
 
 /// Copy the entry's public link, when it has one this client can read the
@@ -1110,27 +1111,29 @@ pub(crate) fn activate_entry(ui: &Rc<Ui>, entry: &DirEntry) {
 /// [`mounted_target`](crate::activation::mounted_target).
 pub(crate) fn download_and_open(ui: &Rc<Ui>, entry: &DirEntry) {
     let rel = entry_rel(ui, entry);
-    let mountpoint = ui.dirs.resolved_mountpoint(&ui.dirs.load_config());
-    if let Some(path) = mounted_target_rel(&mountpoint, &rel) {
-        open_path(&path.to_string_lossy());
-        return;
-    }
-    // Ignore a repeat activation of a file already downloading, so an impatient
-    // double-click doesn't kick off a second round-trip.
+    // Ignore a repeat activation of a file already opening, so an impatient
+    // double-click doesn't open it twice or kick off a second round-trip.
     if !ui.opening.borrow_mut().insert(rel.clone()) {
         return;
     }
+    let mountpoint = ui.dirs.resolved_mountpoint(&ui.dirs.load_config());
+    let (name, uid) = (entry.name.clone(), entry.uid.clone());
+    let ui = ui.clone();
+    glib::spawn_future_local(async move {
+        // Asked off the main thread: a mount that hangs used to hang the app.
+        if let Some(path) = present_within(mounted_path(&mountpoint, &rel)).await {
+            ui.opening.borrow_mut().remove(&rel);
+            open_path(&path.to_string_lossy());
+            return;
+        }
         ui.busy_begin();
-    let name = entry.name.clone();
         let rx = spawn_request(
             ui.dirs.control_socket(),
             Request::OpenFile {
                 path: rel.clone(),
-            uid: Some(entry.uid.clone()),
+                uid: Some(uid),
             },
         );
-    let ui = ui.clone();
-    glib::spawn_future_local(async move {
         let result = rx.recv().await;
         ui.busy_end();
         ui.opening.borrow_mut().remove(&rel);

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

@@ -204,7 +204,9 @@ pub(crate) fn wire_devices(ui: &Rc<Ui>, widgets: &DevicesWidgets) {
 pub(crate) fn devices_status(ui: &Rc<Ui>, icon: &str, title: &str, description: &str, retry: bool) {
     ui.devices.status.set_icon_name(Some(icon));
     ui.devices.status.set_title(title);
-    ui.devices.status.set_description(Some(description));
+    ui.devices
+        .status
+        .set_description(Some(&gtk4::glib::markup_escape_text(description)));
     ui.devices.retry.set_visible(retry);
     ui.devices.content.set_visible_child_name("status");
 }
@@ -390,6 +392,7 @@ fn this_computer_row(
     let row = adw::ActionRow::builder()
         .title(me.map_or_else(|| gettext("This computer"), |d| d.name.clone()))
         .subtitle(this_computer_subtitle(folders))
+        .use_markup(false)
         .activatable(true)
         .build();
     row.add_prefix(&gtk4::Image::from_icon_name("computer-symbolic"));
@@ -426,6 +429,7 @@ fn other_computer_row(ui: &Rc<Ui>, dev: &DeviceInfo) -> adw::ActionRow {
     let row = adw::ActionRow::builder()
         .title(&dev.name)
         .subtitle(device_subtitle(dev))
+        .use_markup(false)
         .activatable(true)
         .build();
     row.add_prefix(&gtk4::Image::from_icon_name("computer-symbolic"));
@@ -440,6 +444,10 @@ fn other_computer_row(ui: &Rc<Ui>, dev: &DeviceInfo) -> adw::ActionRow {
         prompt_restore_folders(&ui_c, Some((uid_c.clone(), name_c.clone())))
     });
     let (ui_c, uid_c, name_c) = (ui.clone(), uid.clone(), name.clone());
+    menu.item(&gettext("Sync With This Computer…"), move || {
+        prompt_join_device(&ui_c, &uid_c, &name_c)
+    });
+    let (ui_c, uid_c, name_c) = (ui.clone(), uid.clone(), name.clone());
     menu.item(&gettext("Move to This Computer…"), move || {
         prompt_migrate_device(&ui_c, &uid_c, &name_c)
     });
@@ -763,7 +771,10 @@ fn show_restore_picker(
             .active(true)
             .valign(gtk4::Align::Center)
             .build();
-        let row = adw::EntryRow::builder().title(&f.name).build();
+        let row = adw::EntryRow::builder()
+            .title(&f.name)
+            .use_markup(false)
+            .build();
         row.set_text(&f.local_path);
         row.add_prefix(&check);
         group.add(&row);
@@ -1093,6 +1104,69 @@ pub(crate) fn prompt_adopt_device(ui: &Rc<Ui>, uid: &str, name: &str) {
     dialog.present(win.as_ref());
 }
 
+/// Ask before syncing into another computer's device alongside it, then offer
+/// its folders for syncing here.
+///
+/// The same adoption as "Continue This Backup Here", but the other computer
+/// goes on syncing, so the dialog says what that means: the two keep the same
+/// folders in step, deletions included.
+pub(crate) fn prompt_join_device(ui: &Rc<Ui>, uid: &str, name: &str) {
+    let win = ui_window(ui);
+    let dialog = adw::AlertDialog::builder()
+        .heading(gettext("Sync With This Computer?"))
+        // Translators: {name} is the name of the other computer this one syncs with.
+        .body(gettext_f(
+            "This computer and “{name}” keep the same folders in step. A change or a deletion on one reaches the other.\n\nNew synced folders on this computer go under “{name}” in Proton Drive. Folders already synced here stay where they are. Next you choose which of its folders to sync here.",
+            &[("name", name)],
+        ))
+        .build();
+    dialog.add_response("cancel", &gettext("Cancel"));
+    dialog.add_response("join", &gettext("Sync Here"));
+    dialog.set_response_appearance("join", adw::ResponseAppearance::Suggested);
+    dialog.set_default_response(Some("cancel"));
+    dialog.set_close_response("cancel");
+    let ui = ui.clone();
+    let uid = uid.to_string();
+    // Translators: {name} is the name of the other computer this one now syncs with.
+    let done = gettext_f("Now syncing with “{name}”", &[("name", name)]);
+    dialog.connect_response(None, move |_, resp| {
+        if resp != "join" {
+            return;
+        }
+        ui.busy_begin();
+        let rx = spawn_request(
+            ui.dirs.control_socket(),
+            Request::AdoptDevice {
+                uid: Some(uid.clone()),
+            },
+        );
+        let (ui, done) = (ui.clone(), done.clone());
+        glib::spawn_future_local(async move {
+            let result = rx.recv().await;
+            ui.busy_end();
+            let failed = gettext("Couldn't sync with that computer");
+            match result {
+                Ok(Ok(Response::Ok { .. })) => {
+                    reload_sync_pages(&ui);
+                    toast(&ui, &done);
+                    // The device is this computer's now, so its own restore
+                    // picker offers the folders.
+                    prompt_restore_folders(&ui, None);
+                }
+                Ok(Ok(Response::Error { message, kind })) => {
+                    toast_failure(&ui, &failed, &message, kind)
+                }
+                _ => toast_error(
+                    &ui,
+                    &failed,
+                    &gettext("The Proton Drive service didn't respond."),
+                ),
+            }
+        });
+    });
+    dialog.present(win.as_ref());
+}
+
 /// Ask before moving another computer's folders into this computer's backup,
 /// then offer them for syncing here.
 ///

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

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

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

@@ -1145,7 +1145,9 @@ pub(crate) fn locations_status(
 ) {
     ui.locations.status.set_icon_name(Some(icon));
     ui.locations.status.set_title(title);
-    ui.locations.status.set_description(Some(description));
+    ui.locations
+        .status
+        .set_description(Some(&gtk4::glib::markup_escape_text(description)));
     ui.locations.retry.set_visible(retry);
     ui.locations.content.set_visible_child_name("status");
 }

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

@@ -9,6 +9,9 @@ pub(crate) struct LoginState {
     /// Spins inside the Sign in button while a sign-in is running.
     pub(crate) login_spinner: Spinner,
     pub(crate) login_status: gtk4::Label,
+    /// Shown over the form while a saved sign-in exists but the keyring would
+    /// not hand it over; see [`keyring_unreadable`].
+    pub(crate) keyring_banner: adw::Banner,
 }
 
 /// Where the login page's account links go.
@@ -87,6 +90,12 @@ pub(crate) fn build_login_page() -> (gtk4::Widget, LoginState) {
         .child(&inner)
         .build();
     let scroll = gtk4::ScrolledWindow::builder().child(&clamp).build();
+    let keyring_banner = adw::Banner::builder()
+        .title(gettext(
+            "Couldn't read your saved sign-in. Unlock the system keyring, then try again.",
+        ))
+        .button_label(gettext("Retry"))
+        .build();
 
     (
         scroll.upcast(),
@@ -96,10 +105,80 @@ pub(crate) fn build_login_page() -> (gtk4::Widget, LoginState) {
             login_button,
             login_spinner,
             login_status,
+            keyring_banner,
         },
     )
 }
 
+/// The stored session, `None` when there is none, or the keyring's error when
+/// it could not be read. A locked or absent keyring is not a sign-out: the
+/// session is still saved, and signing in again would only replace it.
+pub(crate) fn read_session() -> pdfs_core::Result<Option<auth::StoredSession>> {
+    match auth::load() {
+        Ok(session) => Ok(Some(session)),
+        Err(pdfs_core::Error::NotLoggedIn) => Ok(None),
+        Err(e) => Err(e),
+    }
+}
+
+/// How long to wait before each automatic retry of an unreadable keyring. A
+/// keyring daemon started with the session is usually up within seconds.
+const KEYRING_RETRIES: [u32; 4] = [2, 5, 10, 30];
+
+/// The keyring refused to hand over the saved session. Keep the login page up,
+/// but say why, and pick the session up as soon as the keyring answers: on its
+/// own a few times, and whenever the user presses Retry.
+pub(crate) fn keyring_unreadable(ui: &Rc<Ui>, error: &pdfs_core::Error) {
+    tracing::warn!("cannot read the saved session: {error}");
+    let banner = &ui.login.keyring_banner;
+    if banner.is_revealed() {
+        return;
+    }
+    banner.set_revealed(true);
+    let ui_retry = ui.clone();
+    let handler = banner.connect_button_clicked(move |_| retry_session(&ui_retry));
+    // Disconnected once the banner goes, so a later failure wires it afresh.
+    let handler = RefCell::new(Some(handler));
+    banner.connect_revealed_notify(move |banner| {
+        if !banner.is_revealed()
+            && let Some(handler) = handler.borrow_mut().take()
+        {
+            banner.disconnect(handler);
+        }
+    });
+    let ui = ui.clone();
+    glib::spawn_future_local(async move {
+        for seconds in KEYRING_RETRIES {
+            glib::timeout_future_seconds(seconds).await;
+            if !ui.login.keyring_banner.is_revealed() {
+                return;
+            }
+            retry_session(&ui);
+        }
+    });
+}
+
+/// Read the saved session again after [`keyring_unreadable`]. Found: show the
+/// signed-in window. Gone: the plain login page. Still unreadable: keep waiting.
+fn retry_session(ui: &Rc<Ui>) {
+    let ui = ui.clone();
+    glib::spawn_future_local(async move {
+        let Ok(result) = gio::spawn_blocking(read_session).await else {
+            return;
+        };
+        match result {
+            Ok(session) => {
+                ui.login.keyring_banner.set_revealed(false);
+                if session.is_some() && ui.session.borrow().is_none() {
+                    *ui.session.borrow_mut() = session;
+                    refresh(&ui);
+                }
+            }
+            Err(e) => tracing::debug!("the keyring still cannot be read: {e}"),
+        }
+    });
+}
+
 /// Connect the sign-in button: read the fields, run [`auth::login`] on a worker
 /// thread, and report the outcome back on the main loop.
 pub(crate) fn wire_login(ui: &Rc<Ui>) {
@@ -199,7 +278,14 @@ pub(crate) fn wire_login(ui: &Rc<Ui>) {
                     ui.login.login_status.set_text("");
                     ui.login.password.set_text("");
                     // Cache the new identity so `refresh` never hits the keyring.
-                    *ui.session.borrow_mut() = auth::load().ok();
+                    // Read on a worker: a keyring that has to be unlocked first
+                    // answers only once the user has, and the window must not
+                    // freeze until then.
+                    match gio::spawn_blocking(read_session).await {
+                        Ok(Ok(session)) => *ui.session.borrow_mut() = session,
+                        Ok(Err(e)) => keyring_unreadable(&ui, &e),
+                        Err(_) => {}
+                    }
                     // Enable+start the mount service now that we have a session.
                     let _ = gio::spawn_blocking(service::enable_start).await;
                     refresh(&ui);
@@ -602,7 +688,7 @@ pub(crate) fn sign_out(ui: &Rc<Ui>) {
             glib::spawn_future_local(async move {
                 let result = gio::spawn_blocking(|| {
                     service::disable_stop();
-                    auth::logout().map_err(|e| e.to_string())
+                    auth::logout().map(|_| ()).map_err(|e| e.to_string())
                 })
                 .await;
                 if let Ok(Err(e)) = result {

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

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

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

@@ -609,7 +609,7 @@ pub(crate) fn build_gallery_page() -> (gtk4::Widget, GalleryWidgets) {
     select_box.append(&select_done);
     let select_bar = gtk4::Revealer::builder()
         .transition_type(gtk4::RevealerTransitionType::SlideDown)
-        .child(&select_box)
+        .child(&scroll_sideways(&select_box))
         .build();
 
     // All / Photos / Videos / Raw filter. Linked toggles acting as one segmented
@@ -1379,11 +1379,9 @@ pub(crate) fn wire_gallery(
                     "tiff" | "tif" => "image/tiff",
                     _ => "image/jpeg",
                 };
-                let capture_time = std::fs::metadata(&path)
-                    .and_then(|m| m.modified())
-                    .ok()
-                    .and_then(|t| t.duration_since(std::time::SystemTime::UNIX_EPOCH).ok())
-                    .map(|d| d.as_secs() as i64);
+                // The daemon dates the photo: by its EXIF, or by the file's
+                // modification time when it has none.
+                let capture_time = None;
 
                 ui.busy_begin();
                 let rx = spawn_request(
@@ -3459,7 +3457,9 @@ pub(crate) fn load_gallery(ui: &Rc<Ui>, append: bool) {
 pub(crate) fn gallery_status(ui: &Rc<Ui>, icon: &str, title: &str, description: &str, retry: bool) {
     ui.gallery.status.set_icon_name(Some(icon));
     ui.gallery.status.set_title(title);
-    ui.gallery.status.set_description(Some(description));
+    ui.gallery
+        .status
+        .set_description(Some(&gtk4::glib::markup_escape_text(description)));
     ui.gallery.retry.set_visible(retry);
     // Only the empty timeline offers a way to fill it; every other status turns
     // those buttons back off.
@@ -3479,10 +3479,10 @@ pub(crate) fn gallery_unreachable(ui: &Rc<Ui>) {
 /// right tool for the HEVC `.mkv`s this is aimed at — and falls back to the
 /// user's default handler when mpv isn't installed.
 pub(crate) fn play_external(path: &str) {
-    if Command::new("mpv").arg(path).spawn().is_ok() {
-        return;
+    match Command::new("mpv").arg(path).spawn() {
+        Ok(child) => pdfs_core::opener::reap(child),
+        Err(_) => open_path(path),
     }
-    open_path(path);
 }
 
 #[cfg(test)]

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

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

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

@@ -311,7 +311,9 @@ pub(crate) fn wire_shared(ui: &Rc<Ui>, widgets: &SharedWidgets) {
 pub(crate) fn shared_status(ui: &Rc<Ui>, icon: &str, title: &str, description: &str, retry: bool) {
     ui.shared.status.set_icon_name(Some(icon));
     ui.shared.status.set_title(title);
-    ui.shared.status.set_description(Some(description));
+    ui.shared
+        .status
+        .set_description(Some(&gtk4::glib::markup_escape_text(description)));
     ui.shared.retry.set_visible(retry);
     ui.shared.content.set_visible_child_name("status");
 }
@@ -818,6 +820,7 @@ fn invitation_row(inv: &InvitationInfo) -> adw::ActionRow {
         .title(&item)
         // Translators: {email} is the address of the person who sent the invitation.
         .subtitle(gettext_f("From {email}", &[("email", &inv.inviter_email)]))
+        .use_markup(false)
         .build();
     row.add_prefix(&gtk4::Image::from_icon_name(if inv.is_dir {
         "folder-symbolic"
@@ -862,6 +865,7 @@ fn repaint_links(ui: &Rc<Ui>, bookmarks: &[BookmarkInfo]) {
         let row = adw::ActionRow::builder()
             .title(&title)
             .subtitle(&bm.url)
+            .use_markup(false)
             .subtitle_lines(1)
             .activatable(true)
             .tooltip_text(gettext("Open in browser"))

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

@@ -329,7 +329,9 @@ pub(crate) fn shared_by_me_status(
 ) {
     ui.shared_by_me.status.set_icon_name(Some(icon));
     ui.shared_by_me.status.set_title(title);
-    ui.shared_by_me.status.set_description(Some(description));
+    ui.shared_by_me
+        .status
+        .set_description(Some(&gtk4::glib::markup_escape_text(description)));
     ui.shared_by_me.retry.set_visible(retry);
     ui.shared_by_me.content.set_visible_child_name("status");
     ui.shared_by_me.subtitle.set_subtitle("");

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

@@ -860,7 +860,7 @@ pub(crate) fn refresh(ui: &Rc<Ui>) {
                 if ui.stack.visible_child_name().as_deref() == Some("login") {
                     ui.stack.set_visible_child_name("browser");
                 }
-                ui.nav.set_collapsed(false);
+                ui.nav.set_collapsed(ui.narrow.get());
                 if ui.status.account_name.label() != s.username {
                     ui.status.account_name.set_label(&s.username);
                     ui.status.account_name.set_tooltip_text(Some(&s.username));
@@ -1566,6 +1566,7 @@ pub(crate) fn repaint_pins(ui: &Rc<Ui>, pins: &[pdfs_core::cache::Pin], mounted:
         let row = adw::ActionRow::builder()
             .title(&name)
             .subtitle(&pin.path)
+            .use_markup(false)
             .build();
         let icon = gtk4::Image::from_icon_name("pdfs-offline-symbolic");
         row.add_prefix(&icon);

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

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

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

@@ -330,7 +330,9 @@ pub(crate) fn trash_unreachable(ui: &Rc<Ui>) {
 pub(crate) fn trash_status(ui: &Rc<Ui>, icon: &str, title: &str, description: &str, retry: bool) {
     ui.trash.status.set_icon_name(Some(icon));
     ui.trash.status.set_title(title);
-    ui.trash.status.set_description(Some(description));
+    ui.trash
+        .status
+        .set_description(Some(&gtk4::glib::markup_escape_text(description)));
     ui.trash.retry.set_visible(retry);
     ui.trash.content.set_visible_child_name("status");
     ui.trash.subtitle.set_subtitle("");

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

@@ -98,6 +98,8 @@ pub(crate) fn build_details_pane() -> (gtk4::Widget, DetailsWidgets) {
         .title(gettext("Location"))
         .subtitle("—")
         .subtitle_lines(3)
+        // A folder path, which may hold `&` or `<`.
+        .use_markup(false)
         .build();
     path_row.add_css_class("property");
     props.add(&size_row);

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

@@ -491,6 +491,7 @@ pub(crate) fn repaint_share_people(state: &Rc<ShareDialog>, entries: &[ShareEntr
         let row = adw::ActionRow::builder()
             .title(&entry.email)
             .subtitle(&subtitle)
+            .use_markup(false)
             .build();
         row.add_prefix(&adw::Avatar::new(32, Some(&entry.email), true));
 
@@ -506,10 +507,16 @@ pub(crate) fn repaint_share_people(state: &Rc<ShareDialog>, entries: &[ShareEntr
                 .selected(role_wire_to_index(&entry.role))
                 .valign(gtk4::Align::Center)
                 .build();
-            let state_role = state.clone();
+            // Weak, here and in every row below: the rows belong to groups the
+            // dialog state holds, so a strong handle in a row's handler is a
+            // cycle that kept each closed dialog in memory.
+            let state_role = Rc::downgrade(state);
             let id = entry.id.clone();
             let kind = entry.kind;
             drop.connect_selected_notify(move |d| {
+                let Some(state_role) = state_role.upgrade() else {
+                    return;
+                };
                 share_dialog_op(
                     &state_role,
                     state_role.target.update_role(
@@ -539,12 +546,14 @@ pub(crate) fn repaint_share_people(state: &Rc<ShareDialog>, entries: &[ShareEntr
             .valign(gtk4::Align::Center)
             .build();
         remove.add_css_class("flat");
-        let state_rm = state.clone();
+        let state_rm = Rc::downgrade(state);
         let id = entry.id.clone();
         let kind = entry.kind;
         let who = entry.email.clone();
         remove.connect_clicked(move |btn| {
-            let state = state_rm.clone();
+            let Some(state) = state_rm.upgrade() else {
+                return;
+            };
             let id = id.clone();
             let button = btn.clone();
             confirm_destructive(
@@ -605,6 +614,7 @@ pub(crate) fn repaint_share_link(state: &Rc<ShareDialog>, link: Option<&PublicLi
                     url.clone()
                 })
                 .subtitle(&subtitle)
+                .use_markup(false)
                 .build();
             row.add_css_class("property");
 
@@ -615,12 +625,12 @@ pub(crate) fn repaint_share_link(state: &Rc<ShareDialog>, link: Option<&PublicLi
                     .valign(gtk4::Align::Center)
                     .build();
                 copy.add_css_class("flat");
-                let state_copy = state.clone();
+                let ui_copy = state.ui.clone();
                 let url_copy = url.clone();
                 copy.connect_clicked(move |btn| {
                     btn.clipboard().set_text(&url_copy);
                     flash_copied(btn, "edit-copy-symbolic");
-                    toast(&state_copy.ui, &gettext("Link copied"));
+                    toast(&ui_copy, &gettext("Link copied"));
                 });
                 row.add_suffix(&copy);
             }
@@ -631,10 +641,12 @@ pub(crate) fn repaint_share_link(state: &Rc<ShareDialog>, link: Option<&PublicLi
                 .valign(gtk4::Align::Center)
                 .build();
             remove.add_css_class("flat");
-            let state_rm = state.clone();
+            let state_rm = Rc::downgrade(state);
             let id = link.id.clone();
             remove.connect_clicked(move |btn| {
-                let state = state_rm.clone();
+                let Some(state) = state_rm.upgrade() else {
+                    return;
+                };
                 let id = id.clone();
                 let button = btn.clone();
                 confirm_destructive(
@@ -688,9 +700,12 @@ pub(crate) fn repaint_share_link(state: &Rc<ShareDialog>, link: Option<&PublicLi
             let btn = create.clone();
             pw_row.connect_entry_activated(move |_| btn.emit_clicked());
 
-            let state_c = state.clone();
+            let state_c = Rc::downgrade(state);
             let pw_for = pw_row.clone();
             create.connect_clicked(move |btn| {
+                let Some(state_c) = state_c.upgrade() else {
+                    return;
+                };
                 if !btn.is_sensitive() {
                     return;
                 }

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

@@ -219,6 +219,7 @@ fn repaint_versions(state: &Rc<VersionsDialog>, items: &[RevisionInfo]) {
         let row = adw::ActionRow::builder()
             .title(title)
             .subtitle(subtitle)
+            .use_markup(false)
             .build();
 
         let save = gtk4::Button::builder()

crates/pdfs-gui/src/hud/mod.rs

@@ -15,7 +15,6 @@ mod thumbs;
 use std::cell::{Cell, RefCell};
 use std::path::{Path, PathBuf};
 use std::rc::Rc;
-use std::time::Duration;
 
 use adw::prelude::*;
 use gtk4::{gdk, gio, glib};
@@ -24,7 +23,7 @@ use pdfs_core::config::AppDirs;
 use pdfs_core::control::{Request, Response, SearchFilters, SearchHit, SearchSource};
 use pdfs_core::opener::{self, OpenWith};
 
-use crate::activation::{DriveActivation, drive_activation, mounted_or_relative, mounted_target};
+use crate::activation::{DriveActivation, drive_activation, mounted_or_relative, present_within};
 use crate::compat::{Spinner, spinner};
 use crate::theme::set_proton_theme;
 use crate::{
@@ -38,10 +37,6 @@ use thumbs::Thumbs;
 /// Recent files shown above the pinned ones while the query is empty.
 const RECENT_LIMIT: usize = 8;
 
-/// How long opening waits for the mount to answer whether it has a file. A
-/// frozen mount must not freeze the launcher; the daemon is asked instead.
-const STAT_TIMEOUT: Duration = Duration::from_secs(2);
-
 /// The titled groups of the result list.
 #[derive(Debug, Clone, Copy, PartialEq, Eq)]
 enum Section {
@@ -516,22 +511,11 @@ pub(crate) fn build_window(app: &adw::Application) -> Option<Rc<Ui>> {
     Some(ui)
 }
 
-/// Whether the mount has `hit`, asked on a worker thread and given up on
-/// after [`STAT_TIMEOUT`]. `None` means "not there" or "no answer"; either
-/// way the daemon is the fallback.
+/// Whether the mount has `hit`, without blocking the window
+/// ([`present_within`]). `None` means "not there" or "no answer"; either way
+/// the daemon is the fallback.
 async fn mounted_target_within(mountpoint: PathBuf, hit: SearchHit) -> Option<PathBuf> {
-    let (tx, rx) = async_channel::bounded(1);
-    std::thread::spawn(move || {
-        let _ = tx.send_blocking(mounted_target(&mountpoint, &hit));
-    });
-    match glib::future_with_timeout(STAT_TIMEOUT, rx.recv()).await {
-        Ok(Ok(target)) => target,
-        Ok(Err(_)) => None,
-        Err(_) => {
-            tracing::warn!("the mount did not answer in time; opening through the daemon");
-            None
-        }
-    }
+    present_within(mounted_or_relative(&mountpoint, &hit)).await
 }
 
 impl Ui {

crates/pdfs-gui/src/main.rs

@@ -109,7 +109,8 @@ fn sync_line(items: &[TransferItem], jobs: &[JobItem]) -> String {
                     &[("title", &j.title), ("done", &done), ("total", &total)],
                 )
             }
-            Some(j) => format!("{}…", j.title),
+            // Translators: {title} names a running job whose size is not known yet.
+            Some(j) => gettext_f("{title}…", &[("title", &j.title)]),
             None => String::new(),
         },
         [t] => {
@@ -118,10 +119,19 @@ fn sync_line(items: &[TransferItem], jobs: &[JobItem]) -> String {
                 TransferDirection::Upload => "↑",
             };
             if t.bytes_total == 0 {
-                format!("{arrow} {}…", t.name)
+                // Translators: one transfer of unknown size; {arrow} is ↑ or ↓, {name} a file name.
+                gettext_f("{arrow} {name}…", &[("arrow", arrow), ("name", &t.name)])
             } else {
                 let pct = (t.bytes_completed * 100 / t.bytes_total.max(1)).min(100);
-                format!("{arrow} {} ({pct}%)", t.name)
+                // Translators: one transfer; {arrow} is ↑ or ↓, {name} a file name, {percent} how much is done.
+                gettext_f(
+                    "{arrow} {name} ({percent}%)",
+                    &[
+                        ("arrow", arrow),
+                        ("name", &t.name),
+                        ("percent", &pct.to_string()),
+                    ],
+                )
             }
         }
         _ => {
@@ -361,8 +371,9 @@ fn open_manager(args: &[&str]) {
         .and_then(|p| p.parent().map(|d| d.join("pdfs-app")))
         .filter(|p| p.exists())
         .unwrap_or_else(|| PathBuf::from("pdfs-app"));
-    if let Err(e) = Command::new(&exe).args(args).spawn() {
-        tracing::error!("failed to launch {}: {e}", exe.display());
+    match Command::new(&exe).args(args).spawn() {
+        Ok(child) => pdfs_core::opener::reap(child),
+        Err(e) => tracing::error!("failed to launch {}: {e}", exe.display()),
     }
 }
 

docs/ARCHITECTURE.md

@@ -255,7 +255,9 @@ not one this daemon sealed itself (`own_sealed_rev` table), the queued bytes are
 conflict copy (`Core::revision_conflict`) next to the remote version. A name taken on Drive by a
 node this machine has not seen lands under a conflict name too. Both go to the activity log.
 
-Conflict copies are named `{stem} (sync-conflict {unix_secs}).{ext}`.
+Conflict copies are named `{stem} (sync-conflict {host} {unix_secs}).{ext}`, where `{host}` is the
+hostname cut down to one token (`conflict_label`). `conflict_base_name` also reads the older form
+without a host.
 
 ### Failures and sync issues
 
@@ -342,6 +344,22 @@ Safety rules:
 - **Ignore rules.** `.pdfsignore` (or `.protonignore`) at the folder root plus `ignore_patterns`
   from `config.json`, in gitignore syntax. Ignoring never deletes.
 
+Another client may write the same folder, such as a second computer syncing into the device. The
+baseline therefore also records the active revision id each file was synced at (schema 44):
+
+- **A new revision is a remote change** even when the link's modification time and the size come
+  out the same.
+- **An upload checks first.** `upload_revision` reads the node and leaves a file whose revision
+  moved since the walk for the next pass, which classifies it as a conflict. A revision committed
+  between that check and the SDK's own revision draft is not caught.
+- **The baseline records what was transferred.** A download records the revision the pass
+  planned to fetch, not a read-back that may already show a newer one. An upload records the
+  read-back only when its SHA-1 is the one sent.
+- **A first sync compares content.** A path present on both sides without a baseline is adopted
+  only when the local SHA-1 matches Drive's digest; otherwise it is a conflict.
+
+Remote changes still reach a mirror only through the 120 s poll.
+
 ### Moves between locations
 
 My files and each online-only folder are separate FUSE sessions, and a mirrored folder has none,
@@ -369,12 +387,18 @@ named like the hostname, else a new one. An adopted uid that no longer exists is
 replaced silently.
 
 The local database does not survive a lost machine, so the daemon backs up its arrangement to
-`<device root>/.proton-drive-linux/profile.json` (`pdfs_core::profile`): each synced folder's
+`<device root>/.proton-drive-linux/profile-<machine id>.json` (`pdfs_core::profile`): each synced folder's
 remote uid, local path and mode, the pins, and the ignore patterns. It is uploaded like any other
 file, so it is end-to-end encrypted. `Core::touch_profile` coalesces bursts of changes into one
 upload. `PROFILE_VERSION` guards the format: a profile from a newer client is refused, not applied
 in part.
 
+The machine id is random and lives in `machine-id` next to `config.json`. Each machine has its
+own file because several computers may sync into one device: `pdfs devices join` and **Sync With
+This Computer…** adopt another computer's device without taking it over. Restore reads every
+profile there, the legacy shared `profile.json` included, and prefers the one with this hostname,
+then the newest (`profile::saved_folder`).
+
 Restore lists the device's folders, proposes a local path from the profile, and on confirmation
 adds a synced folder bound to the remote uid. The download is an ordinary pass against an empty
 baseline. The user side is in [RECOVERY.md](RECOVERY.md).

docs/CHANGELOG.md

@@ -11,6 +11,126 @@ scratch (user data in `staging/` and `recovery/` is never touched by this).
 
 ## [Unreleased]
 
+## [3.5.0] — 2026-10-16
+
+Schema: **44**. Queued changes get an index by kind and name, and each synced file remembers the
+version on Proton Drive it was synced at. Nothing is rewritten, and the upgrade takes a moment.
+
+### Added
+- **Several computers can sync the same folders.** On the Computers page, **Sync With This
+  Computer…** on another computer, or `pdfs devices join`, makes this computer sync into that
+  computer's backup alongside it, then offers its folders for syncing here. Both computers keep
+  them in step, deletions included. Each computer now keeps its own settings backup in the
+  shared backup, so they no longer overwrite each other (B252).
+- **The app remembers its window size**, and whether it was maximized, between runs.
+
+### Fixed
+- **The app's window could not shrink to fit a small or scaled screen**, so the minimize,
+  maximize and close buttons ended up off-screen. Below about 760 pixels the sidebar and the
+  page now take turns, and every page fits in a window 480 pixels wide.
+- **The app showed the sign-in page when the system keyring was locked or not running yet**, as
+  if the sign-in had been lost. It now says that the keyring could not be read, and opens on its
+  own once the keyring answers (B253).
+- **A new version saved on another computer in the same second as an upload from here could
+  be missed for good** when Drive had not listed the uploaded file yet. The first sync pass
+  after upgrading reads each file's size from Drive once more to close this (B254).
+- **An edit in a synced folder could replace one another computer had just saved.** The newer
+  version from the other computer was left only in the version history. The edit is now kept as
+  a conflict copy (B249).
+- **A version saved on another computer while this one downloaded the previous version never
+  arrived.** (B250)
+- **Syncing a folder into one that already held a file of the same name and size took the two
+  for the same file**, even when their content differed. The content is now compared, and a
+  different file is kept as a conflict copy (B248).
+- **Conflict copies now name the computer that made them**, for example
+  `notes (sync-conflict laptop 1700000000).txt`, so two computers no longer make the same name
+  (B251).
+- **A folder deleted on another device took files with it that had never reached Drive.** A new
+  file, an edit or an ignored `.git` in a synced folder was deleted along with the folder. Such a
+  folder is now kept and created on Drive again (B211).
+- **Files on Drive that could not be decrypted were deleted from the synced folder.** They read
+  as deleted on Drive. They are now left alone and named in the activity feed, and a pass in which
+  nothing synced is left on Drive is refused (B212).
+- **An edit made while a synced folder was being checked could be deleted** when another device
+  had deleted the file. It is now kept and uploaded (B213).
+- **Deleting a synced folder sent another device's new files in it to the trash.** The folder now
+  stays on Drive with them (B214).
+- **A file name on Drive containing `/` or `..` could write outside the synced folder**, and made
+  its folder in the mount fail to list. Such names are left out (B215).
+- **A damaged database lost the changes still waiting to upload.** It is still moved aside and
+  rebuilt, but queued changes, synced folders' state and files kept offline are copied out of it
+  first (B216).
+- **Search slowed down over time, and the database grew far larger than needed.** The search
+  indexes are now compacted once a day; on one machine that took the local index from 317 MiB to
+  20 MiB (B217).
+- **`pdfs diagnose` and `pdfs cache inspect` froze the drive while they checked the database**,
+  for half a minute on a large one. They no longer hold up anything else (B218).
+- **Listing a folder shared with you could freeze the whole drive on a slow connection**, and so
+  could folders of photos asking for thumbnails while the connection stalled (B219, B220).
+- **Opening a large folder for the first time held up every other file operation on the drive.**
+  (B221)
+- **A full disk while saving a file was not reported.** The program saving it now gets the error
+  when it closes the file. Copying a large file into the drive no longer stalls everything else at
+  the end, `fsync` on a file opened for reading no longer fails, and `fallocate` modes the drive
+  cannot honour are refused instead of corrupting the file (B222, B224, B227).
+- **A damaged settings file was replaced with defaults at the next settings change**, losing the
+  mount location and the ignore rules. Settings are no longer saved over a file that cannot be
+  read (B223).
+- **Google Photos import gave some photos another photo's name and date.** A photo without its
+  own metadata file took a similarly named one's, and an edited copy took its original's name. An
+  edited copy now takes its original's date and keeps its own name (B225).
+- **Thumbnails of portrait photos lay on their side**, here and in Proton's own apps (B226).
+- **A write could be lost to a power cut after the program saving it had closed the file.** Saving
+  a change into the upload queue is now written through to disk (B229).
+- **A partly written file whose upload answer was lost came back as a conflict copy of itself.**
+  The retry now recognises its own upload (B228).
+- **A file or folder created offline could merge with another device's of the same name** made
+  while this computer was offline (B230).
+- **A large upload under a low upload limit never finished.** It ran out of time on every try,
+  took the drive offline and started over. Its time limit now allows for its share of the limit
+  (B231).
+- **Every reconnect sent all failed uploads again at once,** including those Proton had refused
+  for a full quota or missing access, and failed uploads were retried no later than every two
+  minutes. Refused uploads now keep their wait, which grows to five minutes, and retries are
+  spread out (B237).
+- **Signing out left the session valid on Proton.** It is now ended there too; `pdfs logout` says
+  so when Proton cannot be reached (B233).
+- **Any folder could be synced, the home folder included,** which uploaded the app's own cache
+  and walked into the drive itself. The root of the file system, the home folder and the folders
+  above it, the Proton Drive folder, the app's own data and folders inside or around another
+  synced folder are now refused, also when restoring another computer's folders (B234).
+- **Names with `&` or `<` showed as empty rows in the app**, and some names were drawn as
+  formatting, for example shared items, computer names and link addresses (B232).
+- **Photos imported from Google Photos, re-dated, or uploaded from the app had no thumbnail** in
+  Proton's apps (B236).
+- **Photos with no other date were filed under the day they were uploaded.** Their own EXIF date
+  is now used, for Google Photos imports and for uploads from the app (B244).
+- **Scanning a Google Photos export with a large folder took up to half a minute.** 10,000 photos
+  now take a tenth of a second (B235).
+- **Every photo opened in the viewer stayed in memory**, with its full-size image, until the app
+  quit. The Share dialog leaked the same way (B241).
+- **Opening a large photo froze the app** while it was decoded (B242).
+- **The app froze when opening a file while the drive did not respond.** It now falls back to
+  downloading the file after two seconds. Applications the app started also no longer linger as
+  zombie processes (B243).
+- **`pdfs import-google-photos --wait` and `pdfs redate-photos --wait` succeeded when the run
+  failed.** They now exit with an error when the run failed, was cancelled or left photos failed,
+  and the app shows why an import failed (B239).
+- **`pdfs mount`, `login`, `unlock` and `logout` could be core-dumped with the account's keys in
+  memory.** Only the background service was protected. A file named like an option, such as
+  `--json`, also broke the file manager's "Keep offline" script (B240).
+- **Signing in while the system keyring was locked froze the app window** until the keyring was
+  unlocked (B246).
+- **A program the background service started could keep it from being restarted when it hung**
+  (B245).
+- **The tray's transfer line was not translated** (B247).
+
+### Changed
+- **Draining a large batch of offline changes no longer slows down with its size.** The queue is
+  indexed by name (schema 43, B238).
+- **Release binaries are stripped of their symbols**: `pdfs` goes from 43 to 35 MB, `pdfs-app`
+  from 24 to 19 MB and `pdfs-tray` from 12 to 8 MB.
+
 ## [3.4.1] — 2026-10-16
 
 Schema: **42**, unchanged.
@@ -1804,6 +1924,7 @@ First stable release: FUSE files-on-demand mount, sync daemon under `proton-driv
 - The outstanding FUSE defects tracked in `docs/BUGS.md`, plus a truncate defect, validated
   by a new POSIX compliance suite for the filesystem.
 
+[3.5.0]: https://github.com/narrrl/proton-drive-linux/releases/tag/v3.5.0
 [3.4.1]: https://github.com/narrrl/proton-drive-linux/releases/tag/v3.4.1
 [3.4.0]: https://github.com/narrrl/proton-drive-linux/releases/tag/v3.4.0
 [3.3.0]: https://github.com/narrrl/proton-drive-linux/releases/tag/v3.3.0

docs/CLI.md

@@ -36,7 +36,7 @@ talks to the running service (`proton-drive.service`); `login`, `logout`, `mount
 | Command | Description |
 |---|---|
 | `pdfs login [-u EMAIL]` | Sign in (password, then a 2FA code if the account has one) and store the session in the system keyring. Restarts the service if it is running. |
-| `pdfs logout` | Remove the stored session. |
+| `pdfs logout` | End the session on Proton and remove the stored session. |
 | `pdfs status` | Account, mount, queue and cache state. |
 | `pdfs quota` | Storage used across all Proton products. |
 | `pdfs locations` | Every local place the service occupies: the Proton Drive folder and each synced folder, with mode and state. |
@@ -102,6 +102,7 @@ commands are for scripts and for cases where the mount is not available.
 | `pdfs devices list` | List computers registered to the account. |
 | `pdfs devices rename UID NAME` | Rename a computer. |
 | `pdfs devices rm UID` | Remove a computer and its backup from the account. |
+| `pdfs devices join UID [--yes]` | Sync the same folders as another computer. This machine syncs into that computer's backup alongside it, then offers its folders like `pdfs sync restore`. Both computers keep them in step. `--yes` skips the confirmation and accepts every proposed path. |
 | `pdfs devices adopt UID` | Make this machine continue another computer's backup, for example after a reinstall. `--clear` returns to matching by hostname. |
 | `pdfs devices migrate UID [--yes]` | Move another computer's folders into this computer's backup, then restore them here like `pdfs sync restore`. The other computer stays registered, without those folders. `--yes` skips the confirmation and accepts every proposed path. See [RECOVERY.md](RECOVERY.md). |
 

docs/CONFIGURATION.md

@@ -14,6 +14,7 @@ and where the client keeps its data.
 | Path | Contents |
 |---|---|
 | `~/.config/proton-drive-linux/config.json` | Settings (this page) |
+| `~/.config/proton-drive-linux/machine-id` | A random id for this machine. It names this machine's profile in a computer's backup that several computers may share |
 | `~/.local/state/proton-drive-linux/cache.db` | Metadata database: names, folder tree, sync state, upload queue, photo index |
 | `~/.local/state/proton-drive-linux/sdk_cache.db` | Encrypted cache of Proton Drive metadata. Safe to delete while the service is stopped |
 | `~/.local/state/proton-drive-linux/control.sock` | Socket the app, tray, prompt and CLI use to reach the service |
@@ -61,6 +62,7 @@ fix it.
   "online_map": false,
   "tray_hidden": false,
   "files_view": { "list": true, "sort": "modified", "descending": true, "folders_first": true },
+  "window": { "width": 980, "height": 680, "maximized": false },
   "open_with": {
     "terminal": ["alacritty", "-e"],
     "rules": [{ "match": ["@text"], "command": ["nvim"], "terminal": true }]
@@ -78,7 +80,7 @@ fix it.
 | `upload_limit` | bytes/s | none | General → Network | Shared cap for all uploads. `0` or `null` means none |
 | `download_limit` | bytes/s | none | General → Network | Shared cap for all downloads, reads from the mount included |
 | `ignore_patterns` | list | see below | — | Global ignore rules for synced folders |
-| `device_uid` | string | none | Computers → Continue This Backup Here… | The computer this machine continues. Unset means "match by hostname" |
+| `device_uid` | string | none | Computers → Continue This Backup Here… or Sync With This Computer… | The computer this machine syncs into. Unset means "match by hostname" |
 | `conflict_sweep` | `off` / `report` / `enforce` | `report` | — | See [`conflict_sweep`](#conflict_sweep) |
 | `local_first` | bool | `true` | — | See [`local_first`](#local_first) |
 | `language` | gettext code | system | General → Appearance | Language of the app, tray and prompt, such as `de` or `pt_BR` |
@@ -86,6 +88,7 @@ fix it.
 | `online_map` | bool | `false` | General → Appearance | Street map for Places from OpenFreeMap |
 | `tray_hidden` | bool | `false` | General → Appearance | Hide the tray icon |
 | `files_view` | object | grid, by name | My files view menu | `list`, `sort` (`name`, `size`, `modified`), `descending`, `folders_first` |
+| `window` | object | 980 × 680 | Resizing the app window | `width`, `height` (the unmaximized size), `maximized` |
 | `open_with` | object | `xdg-open` | — | See [`open_with`](#open_with) |
 | `prompt` | object | built-in window | — | See [`prompt`](#prompt) |
 

docs/RECOVERY.md

@@ -17,7 +17,7 @@ your synced folders back on the replacement machine.
 | Every file that finished uploading | Proton Drive |
 | The computer's registration and its backup | **Computers** in the app and the web |
 | One folder per synced folder, under that computer | Proton Drive |
-| The machine profile: which folders were synced, to which local path, in which mode; pins; ignore patterns | `.proton-drive-linux/profile.json` under the computer's backup, end-to-end encrypted like any other file |
+| The machine profile: which folders were synced, to which local path, in which mode; pins; ignore patterns | `.proton-drive-linux/profile-<machine id>.json` under the computer's backup, one per computer that syncs into it, end-to-end encrypted like any other file. Clients before 3.5.0 wrote `profile.json` |
 | Your account, keys and shares | Proton |
 
 The service rewrites the profile a short while after you add, remove or switch a synced folder,
@@ -166,18 +166,21 @@ This section is for the curious and for anyone debugging a restore.
   in the account is reported in the log instead of being replaced silently.
 - **What can be restored.** `pdfs sync restore` lists the folders directly under the computer's
   backup, except `.proton-drive-linux`. Folders already synced on this machine are skipped.
-- **Proposed paths.** When the profile names a local path whose parent directory exists on this
+- **Proposed paths.** Several computers may sync into one backup, each with its own profile. The
+  profile written by a computer with this machine's hostname is used first, then the newest one
+  that has the folder. When it names a local path whose parent directory exists on this
   machine, that path is proposed. Otherwise the proposal is `~/<folder name>`. The service never
   writes to a path you have not confirmed.
 - **Attaching by UID.** The restore binds each local path to the remote folder's UID, not to its
   name. Restoring `Documents` into `~/docs` works.
 - **Downloading.** A restored folder starts with an empty sync baseline. Against an empty local
   directory, every remote file counts as new and is downloaded. Files present on both sides with
-  no baseline become conflict copies, as described above.
+  no baseline are compared by content: identical files are taken as they are, and different
+  ones become conflict copies, as described above.
 - **The wipe guard.** A sync pass in which every previously synced file has vanished locally is
   refused instead of being mirrored to Proton Drive as a mass deletion. A folder that was emptied
   by accident therefore does not empty the backup.
-- **The profile format.** `profile.json` carries a `version` field. A client refuses a profile
+- **The profile format.** Each profile carries a `version` field. A client refuses a profile
   written by a newer, incompatible client instead of applying part of it.
 
 ## 4. Known gaps

docs/TESTING.md

@@ -5,7 +5,7 @@ Three layers check the client, from fast and offline to slow and against a real
 | Layer | Needs | Runs in CI |
 |---|---|---|
 | [Unit tests](#unit-tests) | Nothing | Every push and pull request |
-| [Simulation runs](#simulation-runs) | `/dev/fuse` | Every push to `main` |
+| [Simulation runs](#simulation-runs) | `/dev/fuse` | Every push to `main` and every pull request |
 | [Acceptance suite](#acceptance-suite) | Nothing for the reference run; a signed-in account for the rest | The reference run only |
 
 ## Unit tests

docs/TROUBLESHOOTING.md

@@ -97,7 +97,15 @@ this block, 5003 is a release Proton no longer accepts.
 
 **Sign-in works but is forgotten after a restart** — no Secret Service provider is running, or its
 keyring is locked. Install and unlock GNOME Keyring, KWallet or KeePassXC (with Secret Service
-enabled). `pdfs diagnose` shows `keyring session` as failing in that case.
+enabled). `pdfs diagnose` shows `keyring session` as failing in that case. When the app finds
+a saved sign-in it cannot read, it says so above the sign-in form and opens on its own once the
+keyring is unlocked. You don't have to sign in again.
+
+**Asked for the mailbox password after every reboot** — the account has a separate mailbox
+password (two-password mode). Such accounts are locked by default: the unlock lasts until you log
+out or restart. To stay unlocked, turn on **Keep unlocked on this computer** in the unlock dialog,
+or run `pdfs unlock --remember`. Either one stores the unlock in the system keyring.
+[SECURITY_MODEL.md](SECURITY_MODEL.md) explains what that trades away.
 
 ## The Proton Drive folder
 

docs/USER_GUIDE.md

@@ -188,15 +188,16 @@ Before you shut down a computer for good, check that nothing is waiting: see
 
 When the same file changed on this computer and somewhere else since the last sync, neither side
 is thrown away. The local version is kept as a copy named like
-`report (sync-conflict 1759068180).odt`, where the number is the time of the conflict in seconds
-since 1970, and the remote version takes the original name.
+`report (sync-conflict laptop 1759068180).odt`, where `laptop` is the name of the computer that
+made the copy and the number is the time of the conflict in seconds since 1970. The remote
+version takes the original name. Copies made before 3.5.0 have no computer name.
 
 Conflicts appear under **Sync → Overview → Needs attention** and in `pdfs conflicts`. For each
 one, keep the original, keep the copy, or keep both under a new name:
 
 ```bash
 pdfs conflicts
-pdfs conflicts resolve "Documents/report (sync-conflict 1759068180).odt" --keep copy
+pdfs conflicts resolve "Documents/report (sync-conflict laptop 1759068180).odt" --keep copy
 ```
 
 The version you do not keep goes to the Trash, so a wrong choice can be undone.
@@ -284,12 +285,31 @@ Proton Drive keeps earlier versions of every file. **Details → Versions…** i
   back folders that are backed up under it but not synced here yet.
 - **Another computer** can be browsed read-only in the same list or grid as My files, and
   **Restore to This Computer…** downloads its folders here.
+- **Sync With This Computer…** makes this computer sync the same folders as another one, for
+  example a desktop and a laptop. Both keep the folders in step: a change or a deletion on one
+  reaches the other. See [Syncing several computers](#syncing-several-computers).
 - **Continue This Backup Here…** makes this computer take over another computer's backup, for
   example after reinstalling or replacing a machine. See [RECOVERY.md](RECOVERY.md).
 - **Move to This Computer…** moves another computer's folders into this computer's backup, for
   example when you switch from Windows to Linux, and then offers them for syncing here. The other
   computer stays in the list, without those folders.
 
+### Syncing several computers
+
+Two or more computers can sync the same folders through one backup in Proton Drive.
+
+1. Sync the folders on the first computer as usual.
+2. On the second computer, open **Computers**, open the menu of the first computer and choose
+   **Sync With This Computer…**. From a terminal: `pdfs devices join UID`, with the UID from
+   `pdfs devices list`.
+3. Choose which of its folders to sync here and where, as in a restore.
+
+From then on, both computers sync into that backup. A folder you add later on either computer
+lands there too, and a folder with the same name joins the one already there. An edit on one
+computer reaches the other within about two minutes. When both computers change the same file in
+that time, each keeps the other's version under the original name and its own as a conflict copy
+named after it. Folders that were synced here before joining stay in this computer's own backup.
+
 ## Search launcher
 
 `pdfs-prompt` searches Proton Drive and your home folder together, in one ranked list. It

packaging/PKGBUILD

@@ -9,7 +9,7 @@
 # Build + install:   cd packaging && makepkg -fi
 
 pkgname=proton-drive-linux
-pkgver=3.4.1
+pkgver=3.5.0
 pkgrel=1
 pkgdesc="Unofficial Proton Drive client for Linux: files-on-demand FUSE mount, CLI, GTK4 app + tray"
 arch=('x86_64')

packaging/proton-drive.service

@@ -8,10 +8,17 @@ PartOf=graphical-session.target
 [Service]
 # Deliberately not Type=notify: the daemon waits for a stored login before it
 # mounts anything, and a machine that boots before the user logs in would then
-# fail the unit on the start timeout. NotifyAccess=all gets the daemon a
-# NOTIFY_SOCKET all the same, which is all the watchdog below needs.
+# fail the unit on the start timeout. NotifyAccess=main gets the daemon a
+# NOTIFY_SOCKET all the same, which is all the watchdog below needs, and keeps
+# its children (fusermount3, ffmpeg, exiftool) from answering the watchdog for
+# it. "all" let any of them do so.
+#
+# Most sandboxing options are left out on purpose: in a user unit, every
+# seccomp-based one (SystemCallFilter, LockPersonality, RestrictAddressFamilies
+# and the like) implies NoNewPrivileges, which stops the setuid fusermount3
+# from mounting anything.
 Type=simple
-NotifyAccess=all
+NotifyAccess=main
 # The daemon waits for a stored login, mounts ~/ProtonDrive, and keeps it
 # mounted. SIGTERM (from `systemctl --user stop`) triggers a clean lazy unmount.
 ExecStart=/usr/bin/pdfs daemon