Fix MBID Mismatch Detector comparing MB title against DB title (filename) instead of embedded tag

The scan was reading `t.title` from the database for comparison, which is
populated from the filename rather than the file's embedded TITLE tag. Any
track whose filename differs from the clean MB title (e.g. includes artist,
album, bitrate) was incorrectly flagged as a mismatch.

Fix: extend `_read_mbid_from_file` → `_read_file_tags` to also read the
embedded TITLE tag (ID3 TIT2, Vorbis `title`, MP4 `©nam`). The comparison
now uses the embedded title, falling back to the DB title only when no TITLE
tag is present in the file.

Fixes #296

core/repair_jobs/mbid_mismatch_detector.py

@@ -54,10 +54,11 @@ def _title_matches(file_title, mb_title):
     return ratio >= TITLE_SIMILARITY_THRESHOLD
 
 
-def _read_mbid_from_file(file_path):
-    """Read the MusicBrainz recording MBID from an audio file's tags.
+def _read_file_tags(file_path):
+    """Read the MusicBrainz recording MBID and embedded title from an audio file's tags.
 
-    Returns (mbid_string, format_name) or (None, None) if not present.
+    Returns (mbid_string, embedded_title, format_name) or (None, None, None) if not readable.
+    The embedded_title may be None if no TITLE tag is present.
     """
     try:
         from mutagen import File as MutagenFile
@@ -68,42 +69,51 @@ def _read_mbid_from_file(file_path):
 
         audio = MutagenFile(file_path)
         if audio is None:
-            return None, None
+            return None, None, None
 
         if isinstance(audio.tags, ID3):
-            # MP3: UFID frame
+            # MP3: UFID frame for MBID
+            mbid = None
             ufid_key = f'UFID:{_MBID_TAG_KEYS["mp3_ufid_owner"]}'
             ufid = audio.tags.get(ufid_key)
             if ufid and ufid.data:
-                return ufid.data.decode('ascii', errors='ignore'), 'mp3'
-            # Also check TXXX fallback (some taggers use this)
-            for key in ['TXXX:MusicBrainz Track Id', 'TXXX:MUSICBRAINZ_TRACKID']:
-                txxx = audio.tags.get(key)
-                if txxx and txxx.text:
-                    return txxx.text[0], 'mp3'
-            return None, None
+                mbid = ufid.data.decode('ascii', errors='ignore')
+            else:
+                # Also check TXXX fallback (some taggers use this)
+                for key in ['TXXX:MusicBrainz Track Id', 'TXXX:MUSICBRAINZ_TRACKID']:
+                    txxx = audio.tags.get(key)
+                    if txxx and txxx.text:
+                        mbid = txxx.text[0]
+                        break
+            # Embedded title from TIT2 frame
+            tit2 = audio.tags.get('TIT2')
+            embedded_title = tit2.text[0] if tit2 and tit2.text else None
+            return mbid, embedded_title, 'mp3' if mbid else None
 
         elif isinstance(audio, (FLAC, OggVorbis)):
             vals = audio.get(_MBID_TAG_KEYS['vorbis'], [])
             if not vals:
                 vals = audio.get('musicbrainz_trackid', [])
-            if vals:
-                return vals[0], 'flac' if isinstance(audio, FLAC) else 'ogg'
-            return None, None
+            mbid = vals[0] if vals else None
+            title_vals = audio.get('title', [])
+            embedded_title = title_vals[0] if title_vals else None
+            fmt = 'flac' if isinstance(audio, FLAC) else 'ogg'
+            return mbid, embedded_title, fmt if mbid else None
 
         elif isinstance(audio, MP4):
             vals = audio.get(_MBID_TAG_KEYS['mp4'], [])
+            mbid = None
             if vals:
                 raw = vals[0]
-                if isinstance(raw, bytes):
-                    return raw.decode('utf-8', errors='ignore'), 'mp4'
-                return str(raw), 'mp4'
-            return None, None
+                mbid = raw.decode('utf-8', errors='ignore') if isinstance(raw, bytes) else str(raw)
+            title_vals = audio.get('\xa9nam', [])
+            embedded_title = title_vals[0] if title_vals else None
+            return mbid, embedded_title, 'mp4' if mbid else None
 
-        return None, None
+        return None, None, None
     except Exception as e:
-        logger.debug("Error reading MBID from %s: %s", file_path, e)
-        return None, None
+        logger.debug("Error reading tags from %s: %s", file_path, e)
+        return None, None, None
 
 
 def _remove_mbid_from_file(file_path):
@@ -275,12 +285,15 @@ class MbidMismatchDetectorJob(RepairJob):
                 result.scanned += 1
                 continue
 
-            # Read MBID from file tags
-            mbid, fmt = _read_mbid_from_file(resolved)
+            # Read MBID and embedded title from file tags
+            mbid, embedded_title, fmt = _read_file_tags(resolved)
             if not mbid:
                 result.scanned += 1
                 continue
 
+            # Use the embedded TITLE tag for comparison; fall back to DB title only if absent
+            file_title = embedded_title if embedded_title else title
+
             # Validate the MBID against MusicBrainz
             checked += 1
 
@@ -318,13 +331,13 @@ class MbidMismatchDetectorJob(RepairJob):
                             mb_artist = credit['artist'].get('name', '')
                             break
 
-                # Compare: does the MBID's title match the file's title?
-                if not _title_matches(title, mb_title):
+                # Compare: does the MBID's title match the file's embedded title?
+                if not _title_matches(file_title, mb_title):
                     self._create_mismatch_finding(
                         context, result, track_id, title, artist_name, album_title,
                         resolved, album_thumb, artist_thumb, mbid,
                         mb_title=mb_title, mb_artist=mb_artist,
-                        reason=f'MBID points to "{mb_title}" by {mb_artist}, expected "{title}"'
+                        reason=f'MBID points to "{mb_title}" by {mb_artist}, expected "{file_title}"'
                     )
 
             except Exception as e: