fix: prefer topic channel for album artist

app/tests/test_ytdl_utils.py

@@ -87,6 +87,40 @@ class AlbumArtistPostProcessorTests(unittest.TestCase):
 
         self.assertEqual(result['album_artist'], 'ScHoolboy Q')
 
+    def test_uses_topic_channel_artist_for_joint_album(self):
+        info = {
+            'album': 'Watch the Throne',
+            'artists': ['JAY-Z', 'Kanye West'],
+            'channel': 'JAY-Z & Kanye West - Topic',
+        }
+
+        _, result = self.postprocessor.run(info)
+
+        self.assertEqual(result['album_artist'], 'JAY-Z & Kanye West')
+
+    def test_uses_topic_uploader_and_strips_suffix_for_compilation(self):
+        info = {
+            'album': 'Compilation',
+            'artist': 'Track Artist',
+            'channel': 'Regular Channel',
+            'uploader': 'Various Artists - Topic',
+        }
+
+        _, result = self.postprocessor.run(info)
+
+        self.assertEqual(result['album_artist'], 'Various Artists')
+
+    def test_regular_channel_falls_back_to_main_artist(self):
+        info = {
+            'album': 'Album',
+            'artist': 'Track Artist',
+            'channel': 'Label Channel',
+        }
+
+        _, result = self.postprocessor.run(info)
+
+        self.assertEqual(result['album_artist'], 'Track Artist')
+
     def test_preserves_explicit_various_artists(self):
         info = {
             'album': 'Revenge of the Dreamers III',

app/ytdl.py

@@ -54,7 +54,9 @@ _LIVE_PROBE_MAX_FAILURES = 5
 
 
 class _AlbumArtistPostProcessor(PostProcessor):
-    """Fill missing album-artist metadata from yt-dlp's main track artist."""
+    """Fill missing album-artist metadata from yt-dlp's album-level signals."""
+
+    _TOPIC_SUFFIX = ' - Topic'
 
     @staticmethod
     def _has_value(value: Any) -> bool:
@@ -76,13 +78,23 @@ class _AlbumArtistPostProcessor(PostProcessor):
             return candidate.split(' · ', 1)[0].strip()
         return None
 
+    @classmethod
+    def _topic_artist(cls, info) -> Optional[str]:
+        for field in ('channel', 'uploader'):
+            value = info.get(field)
+            if not isinstance(value, str) or not value.endswith(cls._TOPIC_SUFFIX):
+                continue
+            if artist := value[:-len(cls._TOPIC_SUFFIX)].strip():
+                return artist
+        return None
+
     def run(self, info):
         if not self._has_value(info.get('album')):
             return [], info
         if self._has_value(info.get('album_artist')) or self._has_value(info.get('album_artists')):
             return [], info
 
-        if artist := self._main_artist(info):
+        if artist := self._topic_artist(info) or self._main_artist(info):
             info['album_artist'] = artist
         return [], info