v0.2.2: device-sync guards — quit warning, sleep/shutdown inhibition

Quitting mid-transfer now asks (Keep Syncing / Quit Anyway) from
closeEvent, which every quit path hits — including the self-update
restart, which previously bypassed closeEvent via a bare quit() and now
routes through close(). A running sync holds its own GNOME inhibitor
(suspend + logout, "Syncing a playlist to a device") so the machine
won't sleep or shutdown/restart under a copy.

Along the way: the Inhibit D-Bus call marshaled Python ints as signed
against GNOME's (susu) signature, so every call was rejected and the
playback sleep inhibitor had silently never worked — _uint fixes both
holders (verified live: cookies taken, IsInhibited flips, releases
clean).

Also investigated trav's mid-copy Syncthing question: the transfer works
from a click-time snapshot and never reads live library state, so remote
changes can't corrupt it — no state freeze needed. Hardened the one real
gap: a source file relocated under the queue (remote metadata edit
moving files) is now skipped, dropped from the m3u, and reported,
instead of aborting the whole sync.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

TASKS.md

@@ -24,6 +24,23 @@ When a round closes, move its finished items to `tasks-done.md`.
 
 # old
 
+## Round 27 — device-sync guards (v0.2.2)
+
+- [x] Quit warning while a transfer is copying (closeEvent; covers X button,
+  Ctrl+Q, MPRIS Quit, and the self-update restart, which used to bypass
+  closeEvent entirely).
+- [x] Machine can't sleep or shutdown/restart mid-transfer: second
+  SleepInhibitor (suspend+logout flags, its own reason text for GNOME's dialog).
+- [x] Found & fixed: the GNOME Inhibit D-Bus call sent signed ints against a
+  (susu) signature, so the *playback* sleep inhibitor had silently never
+  worked — `_uint` marshalling repairs both.
+- [x] Investigated Syncthing changes landing mid-copy: safe by design (the
+  SyncPlan is a click-time snapshot; the worker never reads live library
+  state). Hardened the one gap: a source file relocated under the queue is
+  skipped + dropped from the m3u + reported, instead of aborting the sync.
+
+Tests in `tests/test_round27.py`. Fix round → patch bump **0.2.2**.
+
 ## Round 26 — Device menu: sync playlist to Rabbit R1 (v0.2.0)
 
 - [x] Device menu (left of Track) with "Sync Playlist to Rabbit"; grayed out on

lintunes/__init__.py

@@ -1,3 +1,3 @@
 """LinTunes — iTunes-style music library manager and player for Linux."""
 
-__version__ = "0.2.1"
+__version__ = "0.2.2"

lintunes/device_sync.py

@@ -238,12 +238,25 @@ class DeviceSyncWorker(QObject):
                     pass  # one stubborn file shouldn't kill the sync
             total_kib = max(plan.bytes_to_copy // 1024, 1)
             done = 0
+            vanished: set[str] = set()
             for i, item in enumerate(plan.copies, start=1):
                 label = f"{i}/{len(plan.copies)} {Path(item.dest_name).stem}"
+                # A source gone since planning means Syncthing moved/deleted
+                # it under us (e.g. a metadata edit on the other machine
+                # relocated the file) — skip it, don't abort the transfer.
+                # Once open, the fd pins the inode, so the read stays
+                # consistent even if the file is moved mid-copy.
+                try:
+                    fsrc = open(item.src, "rb")
+                except FileNotFoundError:
+                    vanished.add(item.dest_name)
+                    done += item.size
+                    self.progress.emit(done // 1024, total_kib, label)
+                    continue
                 dest = plan.dest_dir / item.dest_name
                 # Manual chunked copy: byte-accurate progress, and no
                 # copystat (gvfs-MTP rejects it).
-                with open(item.src, "rb") as fsrc, open(dest, "wb") as fdst:
+                with fsrc, open(dest, "wb") as fdst:
                     while True:
                         chunk = fsrc.read(CHUNK)
                         if not chunk:
@@ -253,13 +266,17 @@ class DeviceSyncWorker(QObject):
                         self.progress.emit(done // 1024, total_kib, label)
                 dest = None
             # Written last so an interrupted sync leaves the old m3u intact.
+            # Vanished tracks are left out so the m3u only lists files that
+            # are really there; the next sync picks up their new locations.
+            entries = [e for e in plan.entries if e[0] not in vanished]
             (plan.dest_dir / plan.m3u_name).write_text(
-                build_m3u(plan.entries), encoding="utf-8")
+                build_m3u(entries), encoding="utf-8")
             device_name = plan.device.name if plan.device else "device"
             self.finished.emit({
                 "playlist": plan.playlist_name, "device": device_name,
-                "copied": len(plan.copies), "kept": plan.kept,
+                "copied": len(plan.copies) - len(vanished), "kept": plan.kept,
                 "removed": removed, "skipped": plan.skipped,
+                "vanished": len(vanished),
             })
         except OSError as e:
             if dest is not None:

lintunes/gui/main_window.py

@@ -12,7 +12,7 @@ from PyQt6.QtGui import QAction, QKeySequence
 from lintunes import device_sync, mpris, tagging, theme
 from lintunes.art_search import AlbumArtFetcher
 from lintunes.eventlog import log_control
-from lintunes.inhibit import SleepInhibitor
+from lintunes.inhibit import INHIBIT_LOGOUT, INHIBIT_SUSPEND, SleepInhibitor
 from lintunes.player import Player
 from lintunes.importers import file_importer
 from lintunes.gui.album_art_dialog import AlbumArtDialog
@@ -116,6 +116,12 @@ class MainWindow(QMainWindow):
         self.statusBar().addPermanentWidget(self._sync_progress)
         self._sync_worker = None
         self._sync_device_name = ""
+        # Separate instance from the playback inhibitor: pausing music
+        # mid-sync must not drop the sync's hold. Logout flag included so
+        # GNOME's shutdown/restart dialog names the transfer as the blocker.
+        self._sync_inhibitor = SleepInhibitor(
+            reason="Syncing a playlist to a device",
+            flags=INHIBIT_LOGOUT | INHIBIT_SUSPEND)
 
         # Wiring
         self._transport.play_clicked.connect(self.play_pause)
@@ -158,10 +164,14 @@ class MainWindow(QMainWindow):
         self._update_totals()
 
     def _restart_for_update(self):
-        # The pull already succeeded; quit through the normal path (flushes
+        # The pull already succeeded. Route through close() — not a bare
-        # the library, tears down the player) and let main() re-exec us.
+        # quit() — so closeEvent runs: it flushes the library, tears down the
+        # player, and can veto the restart while a device sync is copying.
         self.restart_requested = True
-        QApplication.instance().quit()
+        if self.close():
+            QApplication.instance().quit()
+        else:
+            self.restart_requested = False
 
     # ---- status bar totals ----
 
@@ -322,6 +332,7 @@ class MainWindow(QMainWindow):
         self._sync_progress.setValue(0)
         self._sync_label.show()
         self._sync_progress.show()
+        self._sync_inhibitor.inhibit()
         self._sync_worker.start()
 
     def _on_sync_progress(self, done_kib, total_kib, label):
@@ -333,6 +344,7 @@ class MainWindow(QMainWindow):
             f"{device_sync.format_bytes(total_kib * 1024)}")
 
     def _on_sync_finished(self, summary):
+        self._sync_inhibitor.release()
         self._sync_label.hide()
         self._sync_progress.hide()
         msg = (f"Synced “{summary['playlist']}” to the {summary['device']}: "
@@ -340,9 +352,13 @@ class MainWindow(QMainWindow):
                f"{summary['removed']} removed")
         if summary["skipped"]:
             msg += f", {summary['skipped']} skipped (no local file)"
+        if summary.get("vanished"):
+            msg += (f", {summary['vanished']} changed under us "
+                    "(re-sync to pick them up)")
         self.statusBar().showMessage(msg, 8000)
 
     def _on_sync_failed(self, message):
+        self._sync_inhibitor.release()
         self._sync_label.hide()
         self._sync_progress.hide()
         QMessageBox.warning(self, "Sync failed", message)
@@ -682,7 +698,26 @@ class MainWindow(QMainWindow):
             self._inhibitor.release()
 
     def closeEvent(self, event):
+        # Quitting mid-transfer abandons a partial file on the device (it
+        # self-heals next sync, but silently) — make it a deliberate choice.
+        if self._sync_worker is not None and self._sync_worker.busy():
+            box = QMessageBox(self)
+            box.setWindowTitle("Sync in progress")
+            box.setText(
+                f"Still copying to the {self._sync_device_name}.\n"
+                "If you quit now, the unfinished track will be re-copied "
+                "on the next sync.")
+            quit_button = box.addButton(
+                "Quit Anyway", QMessageBox.ButtonRole.DestructiveRole)
+            keep = box.addButton(
+                "Keep Syncing", QMessageBox.ButtonRole.RejectRole)
+            box.setDefaultButton(keep)
+            box.exec()
+            if box.clickedButton() is not quit_button:
+                event.ignore()
+                return
         self._inhibitor.release()
+        self._sync_inhibitor.release()
         self.player.shutdown()
         self._manager.flush()
         super().closeEvent(event)

lintunes/inhibit.py

@@ -1,26 +1,43 @@
-"""Keep the machine awake while music is playing.
+"""Keep the machine awake while music plays or a device sync runs.
 
 Uses the GNOME SessionManager D-Bus interface (the same session bus PyQt6's
-QtDBus already talks to for MPRIS) to register a *suspend* inhibitor. GNOME's
+QtDBus already talks to for MPRIS) to register an inhibitor. Playback holds a
-critical-battery action overrides this inhibitor, so a near-dead laptop still
+*suspend* inhibitor; a device sync additionally holds *logout* (which covers
-suspends as expected — we only block idle/automatic suspend while playing.
+shutdown/reboot from the session — GNOME's power dialog names the holder and
+its reason). GNOME's critical-battery action overrides these, so a near-dead
+laptop still suspends as expected.
 
-On non-GNOME desktops the interface won't be available; every method then
+Instances are independent (one D-Bus cookie each), so playback and sync can
-no-ops silently rather than failing.
+hold inhibitors simultaneously without stepping on each other. On non-GNOME
+desktops the interface won't be available; every method then no-ops silently
+rather than failing.
 """
-from PyQt6.QtDBus import QDBusConnection, QDBusInterface, QDBusReply
+from PyQt6.QtCore import QMetaType
+from PyQt6.QtDBus import (QDBusArgument, QDBusConnection, QDBusInterface,
+                          QDBusReply)
 
 
 SERVICE = "org.gnome.SessionManager"
 PATH = "/org/gnome/SessionManager"
+INHIBIT_LOGOUT = 1   # GsmInhibitorFlag: inhibit logout/shutdown/reboot
 INHIBIT_SUSPEND = 4  # GsmInhibitorFlag: inhibit suspending the session/computer
 APP_ID = "org.lintunes.LinTunes"
 REASON = "Playing music"
 
 
+def _uint(value: int) -> QDBusArgument:
+    """Marshal as D-Bus uint32. Inhibit's signature is (susu) — a plain
+    Python int marshals as *signed* int32 and GNOME rejects the whole call
+    with a type error (which QDBusReply reported merely as "invalid", so
+    the inhibitor silently never took effect)."""
+    return QDBusArgument(value, QMetaType.Type.UInt.value)
+
+
 class SleepInhibitor:
-    def __init__(self):
+    def __init__(self, reason: str = REASON, flags: int = INHIBIT_SUSPEND):
         self._cookie: int | None = None
+        self._reason = reason
+        self._flags = flags
         bus = QDBusConnection.sessionBus()
         self._iface = QDBusInterface(SERVICE, PATH, SERVICE, bus)
 
@@ -28,11 +45,11 @@ class SleepInhibitor:
         return self._iface.isValid()
 
     def inhibit(self):
-        """Block automatic suspend. No-op if already inhibiting or unavailable."""
+        """Take the inhibitor. No-op if already inhibiting or unavailable."""
         if self._cookie is not None or not self._available():
             return
         reply = QDBusReply(self._iface.call(
-            "Inhibit", APP_ID, 0, REASON, INHIBIT_SUSPEND))
+            "Inhibit", APP_ID, _uint(0), self._reason, _uint(self._flags)))
         if reply.isValid():
             self._cookie = int(reply.value())
 
@@ -41,5 +58,5 @@ class SleepInhibitor:
         if self._cookie is None:
             return
         if self._available():
-            self._iface.call("Uninhibit", self._cookie)
+            self._iface.call("Uninhibit", _uint(self._cookie))
         self._cookie = None

tests/test_round26.py

@@ -177,15 +177,16 @@ class TestWorker:
         assert seen[-1][0] == seen[-1][1] == 2 * device_sync.CHUNK // 1024
         assert "1/1" in seen[-1][2]
 
-    def test_source_vanishing_reports_failure(self, qapp, tmp_path):
+    def test_device_side_error_reports_failure(self, qapp, tmp_path):
+        # A file squatting on the dest-dir path stands in for a device-side
+        # write error (unplug mid-sync). Vanished *sources* are tolerated
+        # (round 27); device errors still abort.
         a = _audio(tmp_path, "a.mp3")
         plan = plan_sync("Mix", [_track(1, "A", "X", a)], tmp_path / "Music")
-        a.unlink()  # unplugged/deleted between plan and run
+        (tmp_path / "Music").mkdir()
+        (tmp_path / "Music" / "Mix").write_bytes(b"not a dir")
         result = self._synced(qapp, plan)
         assert "Sync failed" in result["error"]
-        # No half-copied file left behind at full-looking size.
-        leftover = plan.dest_dir / "X - A.mp3"
-        assert not leftover.exists() or leftover.stat().st_size != plan.copies[0].size
 
     def test_empty_playlist_clears_folder(self, qapp, tmp_path):
         dest = tmp_path / "Music" / "Mix"

tests/test_round27.py

@@ -0,0 +1,140 @@
+"""Round 27: device-sync guards.
+
+A running transfer now (a) holds a GNOME suspend+logout inhibitor so the
+machine won't sleep or restart under it, (b) is protected by a quit-warning
+in MainWindow.closeEvent (not testable headless — no MainWindow tests exist),
+and (c) tolerates a source file vanishing mid-queue: Syncthing applying a
+remote metadata edit can relocate a music file between planning and copying,
+so the worker skips it, drops it from the m3u, and reports it instead of
+aborting the whole transfer. Device-side errors still abort.
+"""
+
+from lintunes.device_sync import DeviceSyncWorker, plan_sync
+from lintunes.inhibit import INHIBIT_LOGOUT, INHIBIT_SUSPEND, SleepInhibitor
+from lintunes.models import Track
+
+
+def _track(tid, name, artist, path):
+    return Track(track_id=tid, name=name, artist=artist,
+                 location=str(path), total_time=180_000)
+
+
+def _audio(tmp_path, filename, data=b"x" * 100):
+    path = tmp_path / "local" / filename
+    path.parent.mkdir(parents=True, exist_ok=True)
+    path.write_bytes(data)
+    return path
+
+
+class _FakeIface:
+    """Stands in for the QDBusInterface: records calls, hands out cookies."""
+
+    def __init__(self):
+        self.calls = []
+        self._next_cookie = 41
+
+    def isValid(self):
+        return True
+
+    def call(self, method, *args):
+        from PyQt6.QtDBus import QDBusMessage
+        self.calls.append((method, *args))
+        stub = QDBusMessage.createMethodCall("a.b", "/", "a.b", method)
+        if method == "Inhibit":
+            self._next_cookie += 1
+            return stub.createReply([self._next_cookie])
+        return stub.createReply([])
+
+
+class TestSleepInhibitor:
+    def _patched(self, monkeypatch, **kwargs):
+        # _uint wraps ints in write-only QDBusArguments; identity here so the
+        # fake can record and assert on the raw values.
+        from lintunes import inhibit as inhibit_module
+        monkeypatch.setattr(inhibit_module, "_uint", lambda v: v)
+        inhibitor = SleepInhibitor(**kwargs)
+        inhibitor._iface = _FakeIface()
+        return inhibitor
+
+    def test_custom_reason_and_flags_reach_dbus(self, qapp, monkeypatch):
+        inhibitor = self._patched(
+            monkeypatch, reason="Syncing a playlist to a device",
+            flags=INHIBIT_LOGOUT | INHIBIT_SUSPEND)
+        inhibitor.inhibit()
+        method, app_id, xid, reason, flags = inhibitor._iface.calls[0]
+        assert method == "Inhibit"
+        assert reason == "Syncing a playlist to a device"
+        assert flags == 5  # logout (1) + suspend (4)
+
+    def test_defaults_unchanged_for_playback(self, qapp, monkeypatch):
+        inhibitor = self._patched(monkeypatch)
+        inhibitor.inhibit()
+        method, app_id, xid, reason, flags = inhibitor._iface.calls[0]
+        assert reason == "Playing music"
+        assert flags == INHIBIT_SUSPEND == 4
+
+    def test_release_uninhibits_with_cookie(self, qapp, monkeypatch):
+        inhibitor = self._patched(monkeypatch)
+        inhibitor.inhibit()
+        cookie = inhibitor._cookie
+        inhibitor.release()
+        assert ("Uninhibit", cookie) in inhibitor._iface.calls
+        assert inhibitor._cookie is None
+
+    def test_second_inhibit_while_held_is_noop(self, qapp, monkeypatch):
+        inhibitor = self._patched(monkeypatch)
+        inhibitor.inhibit()
+        inhibitor.inhibit()
+        assert len([c for c in inhibitor._iface.calls
+                    if c[0] == "Inhibit"]) == 1
+
+    def test_release_without_hold_is_noop(self, qapp, monkeypatch):
+        inhibitor = self._patched(monkeypatch)
+        inhibitor.release()
+        assert inhibitor._iface.calls == []
+
+
+class TestVanishedSource:
+    def _run(self, plan):
+        worker = DeviceSyncWorker(plan)
+        results = {}
+        worker.finished.connect(lambda s: results.update(s))
+        worker.failed.connect(lambda m: results.update(error=m))
+        worker._run()
+        return results
+
+    def test_vanished_source_is_skipped_not_fatal(self, qapp, tmp_path):
+        a = _audio(tmp_path, "a.mp3", b"a" * 50)
+        b = _audio(tmp_path, "b.mp3", b"b" * 70)
+        tracks = [_track(1, "A", "X", a), _track(2, "B", "Y", b)]
+        plan = plan_sync("Mix", tracks, tmp_path / "Music")
+        a.unlink()  # Syncthing relocated it between plan and copy
+
+        summary = self._run(plan)
+
+        assert "error" not in summary
+        assert summary["vanished"] == 1
+        assert summary["copied"] == 1
+        assert not (plan.dest_dir / "X - A.mp3").exists()
+        assert (plan.dest_dir / "Y - B.mp3").read_bytes() == b"b" * 70
+
+    def test_vanished_track_left_out_of_m3u(self, qapp, tmp_path):
+        a = _audio(tmp_path, "a.mp3")
+        b = _audio(tmp_path, "b.mp3")
+        tracks = [_track(1, "A", "X", a), _track(2, "B", "Y", b)]
+        plan = plan_sync("Mix", tracks, tmp_path / "Music")
+        a.unlink()
+
+        self._run(plan)
+
+        m3u = (plan.dest_dir / "Mix.m3u").read_text(encoding="utf-8")
+        assert "X - A.mp3" not in m3u
+        assert "Y - B.mp3" in m3u
+
+    def test_all_sources_vanished_still_finishes(self, qapp, tmp_path):
+        a = _audio(tmp_path, "a.mp3")
+        plan = plan_sync("Mix", [_track(1, "A", "X", a)], tmp_path / "Music")
+        a.unlink()
+        summary = self._run(plan)
+        assert summary["vanished"] == 1 and summary["copied"] == 0
+        assert (plan.dest_dir / "Mix.m3u").read_text() == "#EXTM3U\n"