Sync rehydration: after loading Deezer ARL playlists, checks each
for active syncs via /api/sync/status and re-attaches polling with
live card updates. Download rehydration: rehydrateModal now handles
deezer_arl_ playlist IDs, and openDownloadMissingModal routes cache
misses to the correct ARL endpoint. Fix All now prompts for dead
file action.
Album data caching: get_playlist_tracks now checks the metadata
cache before fetching album release dates from the Deezer API.
Cache hits are instant, misses are fetched and stored for future
use across all playlists. Import fixed from core.metadata_cache
instead of web_server to avoid circular dependency.