Renaming a Tag renames it in Download settings

update_tag never renamed settings.tag_names, and its channel_tag_name
edit mutated the JSON in place, so it was never saved.  The old name
stayed, and a Download that later found a new Channel failed (UnknownTag).

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

wrolpi/tags.py

@@ -187,15 +187,9 @@ class Tag(ModelHelper, Base):
             from wrolpi.downloader import Download
             to_flush = list()
             for download in session.query(Download):
-                if download.tag_names:
-                    download.tag_names = [i if i != old_name else name for i in download.tag_names]
-                    to_flush.append(download)
-                if download.settings and 'channel_tag_name' in download.settings:
-                    settings = download.settings
-                    tag_name = settings.pop('channel_tag_name')
-                    tag_name = [i for i in tag_name if i != old_name]
-                    settings['channel_tag_name'] = tag_name
-                    download.settings = settings
+                tag_names, settings = with_tag_name_renamed(download.tag_names, download.settings, old_name, name)
+                if tag_names != download.tag_names or settings != download.settings:
+                    download.tag_names, download.settings = tag_names, settings
                     to_flush.append(download)
 
             if to_flush:
@@ -319,6 +313,19 @@ def without_tag_names(download_tag_names: Optional[List[str]], settings: Optiona
     return download_tag_names, settings
 
 
+def with_tag_name_renamed(download_tag_names: Optional[List[str]], settings: Optional[dict], old_name: str,
+                          new_name: str) -> Tuple[Optional[List[str]], Optional[dict]]:
+    """A Download's tag_names and settings with a Tag's old name replaced, in the settings' tag_names and
+    channel_tag_name too.  New objects, so an ORM change to the JSON is seen."""
+    if download_tag_names:
+        download_tag_names = [new_name if i == old_name else i for i in download_tag_names]
+    if settings:
+        settings = {key: [new_name if i == old_name else i for i in value]
+                    if key in ('tag_names', 'channel_tag_name') and value else value
+                    for key, value in settings.items()}
+    return download_tag_names, settings
+
+
 def remove_tag_names_from_downloads(session: Session, names: Set[str]):
     """Remove these Tag names from every Download that would apply them; applying a Tag that does not exist fails
     the download.  (Changes download_manager.yaml.)"""

wrolpi/test/test_tags.py

@@ -569,6 +569,30 @@ async def test_tag_rename_with_channel(test_session, test_directory, video_facto
         tag.delete()
 
 
+@pytest.mark.asyncio
+async def test_tag_rename_downloads(test_session, tag_factory, await_background_tasks):
+    """Renaming a Tag renames it everywhere a Download applies it, including the settings passed on to the
+    Downloads (and Channels) it creates."""
+    from wrolpi.downloader import Download
+    tag, other = await tag_factory('one'), await tag_factory('two')
+    download = Download(url='https://example.com/playlist', downloader='video_channel', tag_names=['one', 'two'],
+                        settings=dict(tag_names=['two', 'one'], channel_tag_name=['one'], video_resolutions=['720p']))
+    untouched = Download(url='https://example.com/other', downloader='video_channel', tag_names=['two'],
+                         settings=dict(tag_names=['two'], channel_tag_name=['two']))
+    test_session.add_all([download, untouched])
+    test_session.commit()
+
+    await tag.update_tag(test_session, 'New Name', None)
+    await await_background_tasks()
+    test_session.commit()
+
+    assert download.tag_names == ['New Name', 'two']
+    assert download.settings == dict(tag_names=['two', 'New Name'], channel_tag_name=['New Name'],
+                                     video_resolutions=['720p'])
+    assert untouched.tag_names == ['two']
+    assert untouched.settings == dict(tag_names=['two'], channel_tag_name=['two'])
+
+
 @pytest.mark.asyncio
 async def test_tags_directory_file_replaced(test_session, test_directory, tag_factory, video_bytes, await_switches):
     """Tags directory hardlinks should update when source file is replaced."""