Add cancellation support to all discovery workers

services/sync_service.py

@@ -239,8 +239,19 @@ class PlaylistSyncService:
             
             logger.info(f"Playlist validation: {len(valid_tracks)}/{len(media_tracks)} tracks are valid {server_type.title()} objects with ratingKeys")
 
-            # Use the validated tracks for the sync
+            # Deduplicate by ratingKey — media servers silently drop duplicates,
-            plex_tracks = valid_tracks # Keep variable name for compatibility with the rest of the function
+            # so count should reflect what actually ends up in the playlist
+            seen_keys = set()
+            deduped_tracks = []
+            for t in valid_tracks:
+                if t.ratingKey not in seen_keys:
+                    seen_keys.add(t.ratingKey)
+                    deduped_tracks.append(t)
+            if len(deduped_tracks) < len(valid_tracks):
+                logger.info(f"Deduplicated {len(valid_tracks) - len(deduped_tracks)} duplicate ratingKeys ({len(valid_tracks)} → {len(deduped_tracks)} tracks)")
+
+            # Use the deduplicated tracks for the sync
+            plex_tracks = deduped_tracks
             
             # Use active media server for playlist sync
             media_client, server_type = self._get_active_media_client()

web_server.py

@@ -20852,6 +20852,8 @@ def update_tidal_playlist_phase(playlist_id):
         return jsonify({"error": str(e)}), 500
 
 
+_playlist_discovery_cancelled = set()  # Set of automation_ids that have been cancelled
+
 def _run_playlist_discovery_worker(playlists, automation_id=None):
     """Background worker that discovers Spotify/iTunes metadata for undiscovered
     mirrored playlist tracks. Stores results in extra_data for use by sync."""
@@ -20931,6 +20933,16 @@ def _run_playlist_discovery_worker(playlists, automation_id=None):
                 log_line=f'{len(undiscovered_tracks)} tracks to discover', log_type='info')
 
             for i, track in enumerate(undiscovered_tracks):
+                # Check for cancellation
+                if automation_id and automation_id in _playlist_discovery_cancelled:
+                    _playlist_discovery_cancelled.discard(automation_id)
+                    print(f"🛑 Playlist discovery cancelled (automation {automation_id})")
+                    _update_automation_progress(automation_id, status='finished', progress=100,
+                                                 phase='Discovery cancelled',
+                                                 log_line=f'Cancelled: {total_discovered} discovered, {total_failed} failed',
+                                                 log_type='info')
+                    return
+
                 total_tracks += 1
                 track_id = track['id']
                 track_name = track.get('track_name', '')
@@ -21995,6 +22007,11 @@ def _run_youtube_discovery_worker(url_hash):
         # Process each track for discovery
         for i, track in enumerate(tracks):
             try:
+                # Check for cancellation (phase changed by reset/delete/close)
+                if state.get('phase') != 'discovering':
+                    print(f"🛑 Discovery cancelled for {url_hash} (phase changed to '{state.get('phase')}')")
+                    return
+
                 # Update progress
                 state['discovery_progress'] = int((i / len(tracks)) * 100)
 
@@ -22297,6 +22314,11 @@ def _run_listenbrainz_discovery_worker(playlist_mbid):
         # Process each track for discovery
         for i, track in enumerate(tracks):
             try:
+                # Check for cancellation
+                if state.get('phase') != 'discovering':
+                    print(f"🛑 ListenBrainz discovery cancelled (phase changed to '{state.get('phase')}')")
+                    return
+
                 # Update progress
                 state['discovery_progress'] = int((i / len(tracks)) * 100)
 
@@ -29417,6 +29439,11 @@ def _run_beatport_discovery_worker(url_hash):
         # Process each track for discovery
         for i, track in enumerate(tracks):
             try:
+                # Check for cancellation
+                if state.get('phase') != 'discovering':
+                    print(f"🛑 Beatport discovery cancelled (phase changed to '{state.get('phase')}')")
+                    return
+
                 # Update progress
                 state['discovery_progress'] = int((i / len(tracks)) * 100)
 

webui/static/script.js

@@ -43112,8 +43112,11 @@ async function clearMirroredDiscovery(playlistId, name) {
         const data = await res.json();
         if (data.success) {
             showToast(`Cleared discovery for ${name} (${data.cleared} tracks)`, 'success');
-            // Also clear the discovery state and remove stale modal DOM
+            // Signal cancellation to any running worker, then clear state
             const hash = `mirrored_${playlistId}`;
+            if (youtubePlaylistStates[hash]) {
+                youtubePlaylistStates[hash].phase = 'cancelled';
+            }
             delete youtubePlaylistStates[hash];
             const staleModal = document.getElementById(`youtube-discovery-modal-${hash}`);
             if (staleModal) staleModal.remove();