feat: show real on-disk tracklist in the Library album modal (#9)

The Library modal showed MusicBrainz's canonical tracklist, hiding incomplete
downloads / edition or track-order mismatches, and showed nothing for albums
without an rgMbid. Now it shows the REAL files on disk.

- LibraryItem gains trackNames String[] (migration add_library_track_names):
  the album's on-disk "## Title.ext" audio filenames.
- Captured at import (pipeline._import lists the final album folder) and at scan
  (scan._record_owned now also refreshes trackNames on re-scan via ON CONFLICT
  DO UPDATE + xmax=0 to preserve the newly-imported flag). New shared
  library.list_audio_files() helper.
- /api/library exposes trackNames; the AlbumModal prefers on-disk tracks when
  present (parsed "## Title" → position/title, zero network, labeled "On disk ·
  N tracks"), falling back to the MusicBrainz listing otherwise. Items imported
  before this column show the MB fallback until re-scanned.

worker 221 tests / 7-skip, web 153, tsc + build clean.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

worker/lyra_worker/library.py

@@ -26,6 +26,20 @@ _COVER_STEMS = {"cover", "folder", "front"}
 _COVER_EXT = {".jpg", ".jpeg", ".png"}
 
 
+def list_audio_files(folder: str) -> list[str]:
+    """The album's on-disk audio filenames (basenames, sorted) — captured into
+    LibraryItem.trackNames so the UI can show the real tracks on disk. Top-level only
+    (albums are one flat folder here); returns [] if the folder is missing/unreadable."""
+    try:
+        names = [
+            n for n in os.listdir(folder)
+            if os.path.isfile(os.path.join(folder, n)) and os.path.splitext(n)[1].lower() in _AUDIO_EXT
+        ]
+    except OSError:
+        return []
+    return sorted(names)
+
+
 def staging_dir(staging_root: str, job_id: str) -> str:
     """A per-job download staging directory under `staging_root`. The staging root may be a
     volume separate from the library (e.g. local disk while the library is an SMB share):

worker/lyra_worker/pipeline.py

@@ -9,7 +9,7 @@ import psycopg
 
 from lyra_worker.adapters.base import SourceAdapter
 from lyra_worker.confidence import score_confidence
-from lyra_worker.library import album_dir, import_album, staging_dir
+from lyra_worker.library import album_dir, import_album, list_audio_files, staging_dir
 from lyra_worker.quality import quality_class
 from lyra_worker.ranker import rank_candidates
 from lyra_worker.types import Candidate, MBTarget
@@ -186,18 +186,19 @@ def _mark_chosen(conn: psycopg.Connection, job_id: str, source_ref: str) -> None
 def _import(conn: psycopg.Connection, job_id: str, target: MBTarget,
             winner: Candidate, path: str) -> None:
     request_id = _request_id(conn, job_id)
+    track_names = list_audio_files(path)  # the real files just imported into the album folder
     with conn.cursor() as cur:
         cur.execute(
             'INSERT INTO "LibraryItem" (id, "requestId", artist, album, path, source, '
-            'format, "qualityClass", "importedAt") '
-            "VALUES (gen_random_uuid()::text, %s, %s, %s, %s, %s, %s, %s, now()) "
+            'format, "qualityClass", "trackNames", "importedAt") '
+            "VALUES (gen_random_uuid()::text, %s, %s, %s, %s, %s, %s, %s, %s, now()) "
             'ON CONFLICT (artist, album) DO UPDATE SET '
             '  "requestId" = EXCLUDED."requestId", path = EXCLUDED.path, source = EXCLUDED.source, '
             '  format = EXCLUDED.format, "qualityClass" = EXCLUDED."qualityClass", '
-            '  "importedAt" = now() '
+            '  "trackNames" = EXCLUDED."trackNames", "importedAt" = now() '
             'WHERE EXCLUDED."qualityClass" > "LibraryItem"."qualityClass"',
             (request_id, target.artist, target.album, path, winner.source,
-             winner.quality.fmt, quality_class(winner.quality)),
+             winner.quality.fmt, quality_class(winner.quality), track_names),
         )
         cur.execute(
             "UPDATE \"Request\" SET status = 'completed' WHERE id = %s", (request_id,)

worker/lyra_worker/scan.py

@@ -5,6 +5,7 @@ from dataclasses import dataclass
 
 import psycopg
 
+from lyra_worker.library import list_audio_files
 from lyra_worker.probe import AudioProbe
 
 _AUDIO_EXT = {".flac", ".mp3", ".m4a", ".opus", ".ogg", ".aac", ".wav"}
@@ -80,14 +81,18 @@ def _record_owned(conn, target, quality_class: int, fmt: str, path: str, watched
                 '  "watchedArtistId" = COALESCE("MonitoredRelease"."watchedArtistId", EXCLUDED."watchedArtistId")',
                 (watched_id, target.artist_mbid, target.artist, target.rg_mbid, target.album, quality_class),
             )
+        track_names = list_audio_files(path)  # capture the real on-disk tracks
         cur.execute(
             'INSERT INTO "LibraryItem" (id, "requestId", artist, album, path, source, format, '
-            '"qualityClass", "importedAt") '
-            "VALUES (gen_random_uuid()::text, NULL, %s, %s, %s, 'scan', %s, %s, now()) "
-            'ON CONFLICT (artist, album) DO NOTHING',
-            (target.artist, target.album, path, fmt, quality_class),
+            '"qualityClass", "trackNames", "importedAt") '
+            "VALUES (gen_random_uuid()::text, NULL, %s, %s, %s, 'scan', %s, %s, %s, now()) "
+            # refresh trackNames on re-scan (populates items imported before this column);
+            # xmax=0 ⇒ this was an INSERT (a genuinely new library item) vs an UPDATE.
+            'ON CONFLICT (artist, album) DO UPDATE SET "trackNames" = EXCLUDED."trackNames" '
+            "RETURNING (xmax = 0) AS inserted",
+            (target.artist, target.album, path, fmt, quality_class, track_names),
         )
-        newly = cur.rowcount == 1  # a new LibraryItem means this album wasn't recorded before
+        newly = cur.fetchone()[0]  # a new LibraryItem means this album wasn't recorded before
     conn.commit()
     return newly
 

worker/tests/test_list_audio_files.py

@@ -0,0 +1,20 @@
+from lyra_worker.library import list_audio_files
+
+
+def test_lists_sorted_audio_basenames_only(tmp_path):
+    (tmp_path / "02 Two.flac").write_bytes(b"")
+    (tmp_path / "01 One.flac").write_bytes(b"")
+    (tmp_path / "10 Ten.mp3").write_bytes(b"")
+    (tmp_path / "cover.jpg").write_bytes(b"")       # non-audio excluded
+    (tmp_path / "notes.txt").write_bytes(b"")       # non-audio excluded
+    (tmp_path / "Disc 1").mkdir()                    # a subdir is not a file
+
+    assert list_audio_files(str(tmp_path)) == ["01 One.flac", "02 Two.flac", "10 Ten.mp3"]
+
+
+def test_missing_dir_returns_empty():
+    assert list_audio_files("/no/such/album/dir") == []
+
+
+def test_empty_dir_returns_empty(tmp_path):
+    assert list_audio_files(str(tmp_path)) == []