fix(fuse,core,gui): routine mirror scans no longer show as syncing

Every mirror pass, the two-minute poll included, reported a "Checking
{folder}" job, and the tray took any job for syncing, so its icon spun
every two minutes over folders with nothing to do.

JobItem gains a background flag (absent from older daemons, so false)
for housekeeping that changes nothing in the user's files: a pass still
scanning, the home index rebuild and the cache integrity check. The tray
keeps them in its menu line but only turns busy for transfers or a job
that is not background; a pass that queues work becomes a Syncing job
and still spins the icon.

The watcher also reconciles only the folder an event lies in, instead of
walking every mirror folder over one edit.

crates/pdfs-core/src/control.rs

@@ -1225,6 +1225,12 @@ pub struct JobItem {
     /// Steps known to need doing, or `0` when unknown (indeterminate progress).
     /// May *grow* mid-job as more work is discovered.
     pub total: u64,
+    /// Housekeeping that changes nothing in the user's files: a mirror folder
+    /// scan that finds nothing to do yet, an index rebuild, a cache check. Front
+    /// ends may show it, but should not report the drive as busy over it. Absent
+    /// from older daemons, which never set it.
+    #[serde(default)]
+    pub background: bool,
 }
 
 /// One in-flight transfer in a [`Response::Transfers`] snapshot.

crates/pdfs-fuse/src/background.rs

@@ -710,7 +710,7 @@ fn scan_local_once(
 
     // The walk has no idea how many files it will find, so the job counts what it
     // has seen and stays indeterminate.
-    let job = transfers.begin_job("Indexing this computer");
+    let job = transfers.begin_background_job("Indexing this computer");
     job.detail("Scanning your files");
     let walked = localindex::scan(&[home], &excludes, |batch| {
         if let Err(e) = db.local_upsert_batch(generation, &batch) {

crates/pdfs-fuse/src/devices.rs

@@ -657,12 +657,16 @@ impl Core {
                     } else {
                         p.total.max(p.done) as u64
                     },
+                    // Most passes find nothing; only one that queues work is
+                    // the drive syncing.
+                    background: true,
                 },
                 SyncPhase::Applying => JobItem {
                     title: format!("Syncing {folder}"),
                     detail: p.current.clone(),
                     done: p.done as u64,
                     total: p.total.max(p.done) as u64,
+                    background: false,
                 },
             });
         }

crates/pdfs-fuse/src/lib.rs

@@ -1034,7 +1034,9 @@ impl Core {
 
         let core = self.clone();
         std::thread::spawn(move || {
-            let job = core.transfers.begin_job("Checking the cache database");
+            let job = core
+                .transfers
+                .begin_background_job("Checking the cache database");
             job.detail("Verifying every page");
             let problems = match core.db.integrity_check() {
                 Ok(problems) => problems,

crates/pdfs-fuse/src/sync.rs

@@ -50,7 +50,7 @@ mod planner;
 use engine::SYNC_CONCURRENCY;
 pub(crate) use engine::{SyncMsg, spawn};
 #[cfg(test)]
-use engine::{classify, settle_with};
+use engine::{classify, event_target, settle_with};
 #[cfg(test)]
 use local_scan::is_write_mode;
 use local_scan::open_for_write_set;
@@ -2097,6 +2097,32 @@ mod tests {
         (ids, started.elapsed())
     }
 
+    #[test]
+    fn a_change_in_one_mirror_folder_reconciles_only_that_folder() {
+        let watched = vec![
+            (PathBuf::from("/home/me/Docs"), 1),
+            (PathBuf::from("/home/me/Photos"), 2),
+            (PathBuf::from("/home/me/Photos/Raw"), 3),
+        ];
+        let target = |paths: &[&str]| {
+            let paths: Vec<PathBuf> = paths.iter().map(PathBuf::from).collect();
+            match event_target(&watched, &paths) {
+                SyncMsg::Reconcile(id) => Some(id),
+                SyncMsg::ReconcileAll => None,
+                _ => panic!("unexpected message"),
+            }
+        };
+        assert_eq!(target(&["/home/me/Docs/a.txt"]), Some(1));
+        // A rename within one folder.
+        assert_eq!(target(&["/home/me/Docs/a", "/home/me/Docs/b"]), Some(1));
+        // The deepest root wins.
+        assert_eq!(target(&["/home/me/Photos/Raw/x.cr2"]), Some(3));
+        // Across folders, outside them all, or no path at all: walk everything.
+        assert_eq!(target(&["/home/me/Docs/a", "/home/me/Photos/a"]), None);
+        assert_eq!(target(&["/home/me/Docsx/a"]), None);
+        assert_eq!(target(&[]), None);
+    }
+
     /// The bug this replaced a fixed sleep for: a save that keeps writing past
     /// the debounce used to be walked mid-write, uploading a torn snapshot as a
     /// real revision. The window has to restart on every event, so settling

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

@@ -57,9 +57,10 @@ pub(crate) fn spawn(core: Core, rx: Receiver<SyncMsg>) -> Option<std::thread::Jo
 fn engine_loop(core: Core, rx: Receiver<SyncMsg>) {
     // Paths the watcher currently covers, mapped to their folder id, so an event
     // path can be resolved back to the folder it belongs to.
-    let watched: Mutex<Vec<(PathBuf, i64)>> = Mutex::new(Vec::new());
+    let watched: Arc<Mutex<Vec<(PathBuf, i64)>>> = Arc::new(Mutex::new(Vec::new()));
 
     let tx_events = core.sync_tx.clone();
+    let watched_events = watched.clone();
     let mut watcher =
         match notify::recommended_watcher(move |res: notify::Result<notify::Event>| {
             let Ok(event) = res else { return };
@@ -67,7 +68,8 @@ fn engine_loop(core: Core, rx: Receiver<SyncMsg>) {
             if matches!(event.kind, notify::EventKind::Access(_)) {
                 return;
             }
-            let _ = tx_events.send(SyncMsg::ReconcileAll);
+            let msg = event_target(&watched_events.lock(), &event.paths);
+            let _ = tx_events.send(msg);
         }) {
             Ok(w) => w,
             Err(e) => {
@@ -256,8 +258,31 @@ fn reconcile_all(core: &Core) {
     }
 }
 
+/// The reconcile a watcher event asks for: the one mirror folder all its paths
+/// lie in, so an edit in one folder does not walk every other one too. An event
+/// that spans folders, or that no watched folder claims (a watch list a moment
+/// out of date), falls back to every folder.
+pub(super) fn event_target(watched: &[(PathBuf, i64)], paths: &[PathBuf]) -> SyncMsg {
+    let mut ids = paths.iter().map(|path| {
+        watched
+            .iter()
+            .filter(|(root, _)| path.starts_with(root))
+            // The deepest root, should one mirror folder sit inside another.
+            .max_by_key(|(root, _)| root.components().count())
+            .map(|(_, id)| *id)
+    });
+    match ids.next() {
+        Some(Some(first)) if ids.all(|id| id == Some(first)) => SyncMsg::Reconcile(first),
+        _ => SyncMsg::ReconcileAll,
+    }
+}
+
 /// Bring the filesystem watches in line with the current mirror-folder set:
 /// watch newly-added folders, drop removed ones.
+///
+/// The watch calls run on a copy, outside the lock: the watcher's event
+/// callback takes the same lock, and a backend that hands a watch request to
+/// its event thread and waits for the answer would deadlock against it.
 fn rewatch(
     core: &Core,
     watcher: &mut notify::RecommendedWatcher,
@@ -274,7 +299,7 @@ fn rewatch(
             return;
         }
     };
-    let mut have = watched.lock();
+    let mut have = watched.lock().clone();
     // Drop watches no longer wanted.
     have.retain(|(path, _)| {
         if want.iter().any(|(p, _)| p == path) {
@@ -294,6 +319,7 @@ fn rewatch(
             Err(e) => warn!(path = %path.display(), error = %e, "sync: watch failed"),
         }
     }
+    *watched.lock() = have;
 }
 
 // ---- reconcile ------------------------------------------------------------

crates/pdfs-fuse/src/transfers.rs

@@ -46,6 +46,8 @@ struct JobEntry {
     detail: Mutex<String>,
     done: AtomicU64,
     total: AtomicU64,
+    /// Housekeeping that moves nothing; see [`JobItem::background`].
+    background: bool,
 }
 
 /// The set of transfers and jobs currently in flight. Cloned `Arc`-style across
@@ -160,12 +162,25 @@ impl TransferRegistry {
     /// that carries its progress and deregisters the job when dropped. The job
     /// starts indeterminate; give it a `total` once one is known.
     pub fn begin_job(self: &Arc<Self>, title: impl Into<String>) -> JobGuard {
+        self.register_job(title.into(), false)
+    }
+
+    /// [`TransferRegistry::begin_job`] for housekeeping the user did not ask
+    /// for and that changes nothing in their files, such as an index rebuild or
+    /// a cache check. It is reported, but front ends don't call the drive busy
+    /// over it.
+    pub fn begin_background_job(self: &Arc<Self>, title: impl Into<String>) -> JobGuard {
+        self.register_job(title.into(), true)
+    }
+
+    fn register_job(self: &Arc<Self>, title: String, background: bool) -> JobGuard {
         let id = self.next.fetch_add(1, Ordering::Relaxed);
         let entry = Arc::new(JobEntry {
-            title: title.into(),
+            title,
             detail: Mutex::new(String::new()),
             done: AtomicU64::new(0),
             total: AtomicU64::new(0),
+            background,
         });
         self.jobs.lock().insert(id, entry.clone());
         JobGuard {
@@ -191,6 +206,7 @@ impl TransferRegistry {
                     detail: e.detail.lock().clone(),
                     done: e.done.load(Ordering::Relaxed),
                     total: e.total.load(Ordering::Relaxed),
+                    background: e.background,
                 }
             })
             .collect()

crates/pdfs-gui/src/main.rs

@@ -88,8 +88,9 @@ struct DriveState {
 /// Summarise a work snapshot into one menu line, or empty when idle. A single
 /// transfer names the file and its percentage; several collapse to counts so the
 /// menu stays one line regardless of queue depth. With nothing moving bytes, a
-/// running job speaks for itself — a scan or an index rebuild is still "busy",
-/// and the tray saying nothing there reads as "finished".
+/// running job speaks for itself — a scan or an index rebuild is still work
+/// going on, and the menu saying nothing there reads as "finished". The icon is
+/// [`busy`]'s call, not this line's.
 fn sync_line(items: &[TransferItem], jobs: &[JobItem]) -> String {
     match items {
         [] => match jobs.first() {
@@ -143,12 +144,12 @@ struct DriveTray {
 fn poll_state(socket: &Path, default_mountpoint: &Path) -> DriveState {
     match send(socket, &Request::Status) {
         Ok(status @ Response::Status { .. }) => {
-            // Same daemon is up, so a cheap follow-up request gives the sync line.
-            let sync = match send(socket, &Request::GetQueueStatus) {
-                Ok(Response::Transfers { items, jobs }) => sync_line(&items, &jobs),
-                _ => String::new(),
+            // Same daemon is up, so a cheap follow-up request says what moves.
+            let (items, jobs) = match send(socket, &Request::GetQueueStatus) {
+                Ok(Response::Transfers { items, jobs }) => (items, jobs),
+                _ => (Vec::new(), Vec::new()),
             };
-            status_state(&status, sync, default_mountpoint)
+            status_state(&status, &items, &jobs, default_mountpoint)
         }
         // Socket answered but with something unexpected — treat as up but odd.
         Ok(_) => unexpected_reply(default_mountpoint),
@@ -217,9 +218,14 @@ fn unexpected_reply(default_mountpoint: &Path) -> DriveState {
     }
 }
 
-/// The state a running daemon's [`Response::Status`] describes, with `sync`
-/// saying what it is moving right now.
-fn status_state(status: &Response, sync: String, default_mountpoint: &Path) -> DriveState {
+/// The state a running daemon's [`Response::Status`] describes, with `items`
+/// and `jobs` saying what it is working on right now.
+fn status_state(
+    status: &Response,
+    items: &[TransferItem],
+    jobs: &[JobItem],
+    default_mountpoint: &Path,
+) -> DriveState {
     let Response::Status {
         mountpoint,
         pinned,
@@ -239,7 +245,7 @@ fn status_state(status: &Response, sync: String, default_mountpoint: &Path) -> D
         paused,
         failing_ops,
         online,
-        queued.is_some() || !sync.is_empty(),
+        queued.is_some() || busy(items, jobs),
     );
     DriveState {
         line: match (online, queued) {
@@ -278,11 +284,19 @@ fn status_state(status: &Response, sync: String, default_mountpoint: &Path) -> D
         mounted: true,
         paused,
         mountpoint: PathBuf::from(mountpoint),
-        sync,
+        sync: sync_line(items, jobs),
         failing: failing_ops,
     }
 }
 
+/// Whether the daemon is changing something: bytes moving, or a job the user
+/// is waiting on. A mirror folder's routine scan and the like are background
+/// jobs; they still get the menu line, but the icon spinning every two minutes
+/// for a scan that finds nothing reads as constant syncing.
+fn busy(items: &[TransferItem], jobs: &[JobItem]) -> bool {
+    !items.is_empty() || jobs.iter().any(|j| !j.background)
+}
+
 /// The phase a running mount is in. A pause is the user's own doing and says
 /// so first; failures outrank everything else the daemon reports.
 fn phase_of(paused: bool, failing: u64, online: bool, busy: bool) -> Phase {
@@ -547,11 +561,7 @@ fn main() -> Result<()> {
             heard.take(feed);
         }
         let st = match &heard.status {
-            Some(status) => status_state(
-                status,
-                sync_line(&heard.items, &heard.jobs),
-                &default_mountpoint,
-            ),
+            Some(status) => status_state(status, &heard.items, &heard.jobs, &default_mountpoint),
             // Lost the daemon: ask once, which describes the sign-in instead.
             None => poll_state(&socket, &default_mountpoint),
         };
@@ -596,6 +606,39 @@ mod tests {
         assert_eq!(phase_of(false, 0, true, false), Phase::Synced);
     }
 
+    fn job(title: &str, background: bool) -> JobItem {
+        JobItem {
+            title: title.to_string(),
+            detail: String::new(),
+            done: 0,
+            total: 0,
+            background,
+        }
+    }
+
+    #[test]
+    fn a_routine_scan_is_not_busy_but_a_sync_is() {
+        assert!(!busy(&[], &[]));
+        assert!(!busy(&[], &[job("Checking Documents", true)]));
+        assert!(busy(
+            &[],
+            &[
+                job("Checking Documents", true),
+                job("Syncing Photos", false)
+            ]
+        ));
+        assert!(busy(&[], &[job("Uploading files", false)]));
+    }
+
+    #[test]
+    fn a_job_from_an_older_daemon_counts_as_busy() {
+        let job: JobItem = serde_json::from_str(
+            r#"{"title":"Checking Documents","detail":"","done":0,"total":0}"#,
+        )
+        .unwrap();
+        assert!(!job.background);
+    }
+
     #[test]
     fn the_issues_item_counts_in_the_singular_and_plural() {
         assert_eq!(issues_label(1), "1 issue — View");