Fix Explore tab checkmark badge not persisting after refresh

Explored status was stored only in frontend memory; on reload the badge
disappeared because the API never returned it. Added explored_at column
to mirrored_playlists (auto-migrated), written when build-tree completes,
and read back via SELECT * so the badge survives page refreshes.

database/music_database.py

@@ -517,6 +517,9 @@ class MusicDatabase:
             """)
             cursor.execute("CREATE INDEX IF NOT EXISTS idx_arh_automation_id ON automation_run_history(automation_id)")
 
+            # Add explored_at to mirrored_playlists (migration)
+            self._add_mirrored_playlist_explored_column(cursor)
+
             # Add notification columns to automations (migration)
             self._add_automation_notify_columns(cursor)
             self._add_automation_system_column(cursor)
@@ -684,6 +687,17 @@ class MusicDatabase:
             logger.error(f"Error initializing database: {e}")
             raise
     
+    def _add_mirrored_playlist_explored_column(self, cursor):
+        """Add explored_at column to mirrored_playlists to persist explore badge."""
+        try:
+            cursor.execute("PRAGMA table_info(mirrored_playlists)")
+            cols = [c[1] for c in cursor.fetchall()]
+            if 'explored_at' not in cols:
+                cursor.execute("ALTER TABLE mirrored_playlists ADD COLUMN explored_at TIMESTAMP DEFAULT NULL")
+                logger.info("Added explored_at column to mirrored_playlists table")
+        except Exception as e:
+            logger.error(f"Error adding explored_at column to mirrored_playlists: {e}")
+
     def _add_automation_notify_columns(self, cursor):
         """Add notification and result columns to automations table."""
         try:
@@ -10490,6 +10504,21 @@ class MusicDatabase:
             logger.error(f"Error getting mirrored playlists: {e}")
             return []
 
+    def mark_mirrored_playlist_explored(self, playlist_id: int) -> bool:
+        """Set explored_at to now for a mirrored playlist."""
+        try:
+            with self._get_connection() as conn:
+                cursor = conn.cursor()
+                cursor.execute(
+                    "UPDATE mirrored_playlists SET explored_at = CURRENT_TIMESTAMP WHERE id = ?",
+                    (playlist_id,)
+                )
+                conn.commit()
+                return cursor.rowcount > 0
+        except Exception as e:
+            logger.error(f"Error marking playlist {playlist_id} as explored: {e}")
+            return False
+
     def get_mirrored_playlist(self, playlist_id: int) -> Optional[Dict]:
         """Return a single mirrored playlist by id."""
         try:

web_server.py

@@ -49288,6 +49288,7 @@ def playlist_explorer_build_tree():
                 if idx < len(artist_groups) - 1:
                     time.sleep(0.2)
 
+            get_database().mark_mirrored_playlist_explored(playlist_id)
             yield json.dumps({"type": "complete", "total_artists": len(artist_groups), "total_albums": total_albums}) + '\n'
 
         return Response(generate(), mimetype='application/x-ndjson', headers={

webui/static/script.js

@@ -71743,7 +71743,7 @@ function explorerRenderPickerCards(source) {
         const isReady = pct >= 50;
         const isActive = _explorer.playlistId === p.id;
         const isFullyDiscovered = pct === 100;
-        const wasExplored = p.explored || false;
+        const wasExplored = !!(p.explored_at || p.explored);
         const wishlisted = p.wishlisted_count || 0;
         const inLibrary = p.in_library_count || 0;
 
@@ -71967,10 +71967,10 @@ async function explorerBuildTree() {
         if (progress) progress.style.display = 'none';
         _explorerUpdateCount();
 
-        // Mark playlist as explored (persists in session for badge display)
+        // Mark playlist as explored (server persists via explored_at; update local copy too)
         const exploredPl = _explorer._playlists.find(p => p.id === playlistId);
         if (exploredPl) {
-            exploredPl.explored = true;
+            exploredPl.explored_at = new Date().toISOString();
             // Update card badge without full re-render
             const card = document.querySelector(`.explorer-picker-card[data-id="${playlistId}"]`);
             if (card) {