Resume a figure after a library rescan

play_figure resumed only when the player's playlist *was* the figure's playlist
object. rescan_library rebuilds every Playlist, so after the refresh button - or
the podcast poller landing a new episode, every few hours on its own - putting a
figure back started it over. Playlist is a frozen dataclass: compare by value.

The album picker's "keep what is already playing" check had the same identity
comparison and restarted the album after a rescan; it compares by value too.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

python-backend/musicmouse/__main__.py

@@ -316,9 +316,6 @@ def _build_app(
         mouse=mouse,
         player=player,
         library=library,
-        # One source of truth: the figure path and the web path must hand the player the
-        # same Playlist object for the same folder, because `play_figure` resumes on an
-        # identity check.
         playlists=library.figure_playlists(),
         clock=clock,
         tippen=tippen,

python-backend/musicmouse/library/__init__.py

@@ -132,9 +132,6 @@ class MusicLibrary:
         one per subfolder, depth-first and alphabetical, which is the order the LED ring
         offers them in - and the ring has room for no more than
         :data:`MAX_FIGURE_ALBUMS`.
-
-        The figure path and the web path must hand the player the *same* object for the
-        same album: ``reactions.playback.play_figure`` resumes on an identity check.
         """
         by_figure: dict[str, list[Album]] = {}
         for album, _ in self._entries.values():

python-backend/musicmouse/reactions/playback.py

@@ -75,7 +75,11 @@ def play_figure(event: PlayFigureRequested, app: App) -> None:
     playlist = choices[app.default_choice(event.figure)]
     remember_figure_album(app, event.figure, playlist)
 
-    if not event.restart and app.player.playlist is playlist:
+    # Equality, not identity: a library rescan (the refresh button, or the podcast
+    # poller landing an episode) rebuilds every Playlist object, and an `is` check made
+    # the figure start over after that. Equal means the same album with the same files;
+    # if the files changed, starting over is the honest thing to do.
+    if not event.restart and app.player.playlist == playlist:
         _log.info("Resuming %r", event.figure)
         app.player.play()
         return
@@ -92,8 +96,7 @@ def remember_figure_album(app: App, figure: str, playlist: Playlist) -> None:
 
 
 def _start_album(app: App, album: Album, track_index: int) -> None:
-    # A figure album keeps the figure's own resume bookkeeping honest: it is the same
-    # Playlist object either way, because both come from the library index.
+    # A figure album started from anywhere becomes the album that figure picks next.
     playlist = None
     if album.figure is not None:
         playlist = next(

python-backend/musicmouse/reactions/selection.py

@@ -130,7 +130,8 @@ def selector_pressed(_event: SelectorPressed, app: App) -> None:
     playlist = selector.choices[selector.selected]
     _close(app, fade=True)
     _play_sound(app, confirm_wav, CONFIRM_GAIN)
-    if app.player.playlist is playlist:
+    # By value: a rescan rebuilds the Playlist objects (see play_figure).
+    if app.player.playlist == playlist:
         _log.info("Album picker: keeping %s", playlist.album_id)
         return
     _log.info("Album picker: %r -> %s", selector.figure, playlist.album_id)

python-backend/tests/test_reactions.py

@@ -126,6 +126,22 @@ async def test_putting_the_same_figure_back_resumes_where_it_left_off(
     mouse.check("track", "1")
 
 
+async def test_resuming_survives_a_library_rescan(
+    mouse: SimulatorDriver, sim: Simulation
+) -> None:
+    """A rescan rebuilds every Playlist object; resuming must not depend on identity."""
+    await mouse.place("fuchs")
+    await mouse.wait(TRACK_SECONDS + 1)
+    mouse.check("track", "1")
+
+    await mouse.remove()
+    await sim.app.rescan_library()
+    await mouse.place("fuchs")
+
+    mouse.check("playing", "true")
+    mouse.check("track", "1")
+
+
 async def test_a_different_figure_starts_from_the_top(mouse: SimulatorDriver) -> None:
     await mouse.place("fuchs")
     await mouse.wait(TRACK_SECONDS + 1)

python-backend/tests/test_web.py

@@ -199,15 +199,15 @@ async def test_play_can_start_at_a_track(client: Client, sim: Simulation) -> Non
     assert (await client.get("/api/state")).json()["track_index"] == 2
 
 
-async def test_playing_a_figure_album_reuses_the_figure_playlist(
+async def test_playing_a_figure_album_plays_the_figure_playlist(
     client: Client, sim: Simulation
 ) -> None:
-    """Identity matters: ``play_figure`` resumes on an ``is`` check."""
+    """Equal to the figure's own playlist, so placing the figure afterwards resumes it."""
     album = await album_by_title(client, "Fuchs")
     await client.post("/api/play", json={"album_id": album["id"]})
     await sim.bus.drain()
 
-    assert sim.player.playlist is sim.app.playlists["fuchs"][0]
+    assert sim.player.playlist == sim.app.playlists["fuchs"][0]
 
 
 async def test_playing_an_unknown_album_is_a_404(client: Client) -> None: