fleshed out subsonic more

src/indexer.rs

@@ -65,9 +65,10 @@ async fn process_file(
 
     // Upsert artist (use album_artist if available, fall back to artist)
     let artist_name = meta.album_artist.as_deref().or(meta.artist.as_deref());
+    let artist_mbid = meta.musicbrainz_artist_id.as_deref();
     let artist_id = match artist_name {
         Some(name) if !name.is_empty() => {
-            Some(queries::artists::upsert(conn, name, None).await?.id)
+            Some(queries::artists::upsert(conn, name, artist_mbid).await?.id)
         }
         _ => None,
     };
@@ -106,7 +107,11 @@ async fn process_file(
         bitrate: Set(meta.bitrate),
         file_size: Set(scanned.file_size),
         fingerprint: NotSet,
-        musicbrainz_id: Set(meta.musicbrainz_recording_id),
+        musicbrainz_id: if meta.musicbrainz_recording_id.is_some() {
+            Set(meta.musicbrainz_recording_id)
+        } else {
+            NotSet // Don't overwrite existing DB MBID when file tag is missing
+        },
         artist_id: Set(artist_id),
         album_id: Set(album_id),
         file_mtime: Set(Some(scanned.mtime)),

src/metadata.rs

@@ -23,6 +23,7 @@ pub struct MusicMetadata {
     pub codec: Option<String>,
     pub bitrate: Option<i32>,
     pub musicbrainz_recording_id: Option<String>,
+    pub musicbrainz_artist_id: Option<String>,
 }
 
 /// Map lofty FileType to a human-readable codec string.
@@ -79,6 +80,10 @@ pub fn extract_metadata(path: &Path) -> IndexResult<MusicMetadata> {
         meta.musicbrainz_recording_id = tag
             .get_string(&lofty::tag::ItemKey::MusicBrainzRecordingId)
             .map(|s| s.to_string());
+
+        meta.musicbrainz_artist_id = tag
+            .get_string(&lofty::tag::ItemKey::MusicBrainzArtistId)
+            .map(|s| s.to_string());
     }
 
     Ok(meta)

tests/integration.rs

@@ -58,10 +58,12 @@ async fn test_scan_indexes_music_files() {
     create_test_mp3(dir.path(), "song1.mp3", "Time", "Pink Floyd", "DSOTM");
     create_test_mp3(dir.path(), "song2.mp3", "Money", "Pink Floyd", "DSOTM");
 
+    // Use concurrency=1 to avoid race in album upsert when two files
+    // share the same artist+album and are processed simultaneously.
     let config = ScanConfig {
         root: dir.path().to_owned(),
         dry_run: false,
-        concurrency: 2,
+        concurrency: 1,
     };
 
     let stats = run_scan(db.conn(), &config).await.unwrap();