fix(metadata): preserve the selected recording during download enrichment

lib/services/download_track_metadata.dart

@@ -1,6 +1,7 @@
 import 'package:spotiflac_android/models/track.dart';
 import 'package:spotiflac_android/services/platform_bridge.dart';
 import 'package:spotiflac_android/utils/int_utils.dart';
+import 'package:spotiflac_android/utils/isrc_utils.dart';
 import 'package:spotiflac_android/utils/logger.dart';
 import 'package:spotiflac_android/utils/string_utils.dart';
 
@@ -26,18 +27,32 @@ Future<Track> enrichIncompleteDownloadTrack(
     final data = response['track'];
     if (data is! Map<String, dynamic>) return track;
     String? text(String key) => normalizeOptionalString(data[key]?.toString());
+    final selectedIsrc = normalizeIsrc(track.isrc);
+    final resolvedIsrc = normalizeIsrc(text('isrc'));
+    if (selectedIsrc.isNotEmpty &&
+        resolvedIsrc.isNotEmpty &&
+        selectedIsrc != resolvedIsrc) {
+      AppLogger(
+        'DownloadMetadata',
+      ).w('Ignoring supplemental metadata for a different recording');
+      return track;
+    }
     final durationMs = readPositiveInt(data['duration_ms']);
     return track.copyWith(
-      id: text('spotify_id') ?? track.id,
-      name: text('name') ?? track.name,
-      artistName: text('artists') ?? track.artistName,
+      // This lookup fills missing credits; the selected track still determines
+      // which recording is downloaded and named (including remix qualifiers).
+      name: normalizeOptionalString(track.name) ?? text('name') ?? track.name,
+      artistName:
+          normalizeOptionalString(track.artistName) ??
+          text('artists') ??
+          track.artistName,
       albumName: text('album_name') ?? track.albumName,
       albumArtist: text('album_artist') ?? track.albumArtist,
       artistId: text('artist_id') ?? text('artistId') ?? track.artistId,
       albumId: text('album_id') ?? track.albumId,
       coverUrl: text('images') ?? track.coverUrl,
       duration: durationMs == null ? track.duration : durationMs ~/ 1000,
-      isrc: text('isrc') ?? track.isrc,
+      isrc: normalizeOptionalString(track.isrc) ?? text('isrc'),
       trackNumber: readPositiveInt(data['track_number']) ?? track.trackNumber,
       discNumber: readPositiveInt(data['disc_number']) ?? track.discNumber,
       totalDiscs: readPositiveInt(data['total_discs']) ?? track.totalDiscs,

test/download_track_metadata_test.dart

@@ -78,6 +78,57 @@ void main() {
     expect(enriched.toJson(), original.toJson());
   });
 
+  for (final remix in [false, true]) {
+    test(
+      'supplemental credits cannot rename the selected recording (remix=$remix)',
+      () async {
+        final selected = original.copyWith(
+          name: remix ? 'Song (Club Remix)' : 'Song',
+          isrc: 'USAAA2400001',
+        );
+        final enriched = await enrichIncompleteDownloadTrack(
+          selected,
+          'example',
+          'track',
+          loadMetadata: (_, _, _) async => {
+            'track': {
+              'spotify_id': 'example:other-recording',
+              'name': remix ? 'Song' : 'Song (Club Remix)',
+              'artists': 'Another artist',
+              'composer': 'Composer',
+            },
+          },
+        );
+        expect(enriched.id, selected.id);
+        expect(enriched.name, selected.name);
+        expect(enriched.artistName, selected.artistName);
+        expect(enriched.isrc, selected.isrc);
+        expect(enriched.composer, 'Composer');
+      },
+    );
+  }
+
+  test(
+    'conflicting ISRC rejects all supplemental recording metadata',
+    () async {
+      final selected = original.copyWith(isrc: 'US-AAA-24-00001');
+      final enriched = await enrichIncompleteDownloadTrack(
+        selected,
+        'example',
+        'track',
+        loadMetadata: (_, _, _) async => {
+          'track': {
+            'isrc': 'USAAA2400002',
+            'album_name': 'Another Album',
+            'images': 'https://example.test/another-cover',
+            'composer': 'Another Composer',
+          },
+        },
+      );
+      expect(enriched, same(selected));
+    },
+  );
+
   test(
     'complete tracks avoid an extra lookup and failed lookups keep source metadata',
     () async {