Fix batch completion detection for post-processing race condition

web_server.py

@@ -16180,15 +16180,22 @@ def _on_download_completed(batch_id, task_id, success=True):
         # Guard against double-calling: track which tasks have already been completed
         # This prevents active_count from being decremented multiple times for the same task
         # (e.g. monitor detects completion AND post-processing calls this again)
+        # NOTE: On duplicate calls, we skip decrement/tracking but STILL check batch completion.
+        # This is critical because the first call may see the task in 'post_processing' (not finished),
+        # and the second call (from post-processing worker) arrives after the task is truly 'completed'.
+        # Without the fallthrough, batch_complete would never be emitted.
         completed_tasks = download_batches[batch_id].setdefault('_completed_task_ids', set())
-        if task_id in completed_tasks:
-            print(f"⚠️ [Batch Manager] Task {task_id} already completed — skipping duplicate _on_download_completed call")
+        _is_duplicate_completion = task_id in completed_tasks
+        if _is_duplicate_completion:
+            print(f"⚠️ [Batch Manager] Task {task_id} already completed — skipping decrement, still checking batch completion")
             # Set terminal status so the monitor loop stops re-processing this task
             if task_id in download_tasks and download_tasks[task_id].get('status') in ('downloading', 'queued'):
                 download_tasks[task_id]['status'] = 'completed'
-            return
+            # Fall through to batch completion check below (don't return)
+        else:
             completed_tasks.add(task_id)
 
+        if not _is_duplicate_completion:
             # Track failed/cancelled tasks in batch state (replicating sync.py)
             if not success and task_id in download_tasks:
                 task = download_tasks[task_id]
@@ -16274,7 +16281,7 @@ def _on_download_completed(batch_id, task_id, success=True):
 
             print(f"🔄 [Batch Manager] Task {task_id} completed ({'success' if success else 'failed/cancelled'}). Active workers: {old_active} → {new_active}/{download_batches[batch_id]['max_concurrent']}")
 
-        # ENHANCED: Always check batch completion after any task completes
+        # ENHANCED: Always check batch completion after any task completes (including duplicate calls)
         # This ensures completion is detected even when mixing normal downloads with cancelled tasks
         print(f"🔍 [Batch Manager] Checking batch completion after task {task_id} completed")
         
@@ -16392,6 +16399,9 @@ def _on_download_completed(batch_id, task_id, success=True):
                 else:
                     # For manual batches, use standard wishlist processing
                     missing_download_executor.submit(_process_failed_tracks_to_wishlist_exact, batch_id)
+            else:
+                print(f"✅ [Batch Manager] Batch {batch_id} already marked complete - skipping duplicate processing")
+
             return  # Don't start next batch if we're done
     
     # Start next downloads in queue
@@ -18680,6 +18690,24 @@ def _check_batch_completion_v2(batch_id):
                     # Mark batch as complete and set completion timestamp for auto-cleanup
                     batch['phase'] = 'complete'
                     batch['completion_time'] = time.time()  # Track when batch completed
+
+                    # Add activity for batch completion
+                    playlist_name = batch.get('playlist_name', 'Unknown Playlist')
+                    failed_count = len(batch.get('permanently_failed_tracks', []))
+                    successful_downloads = finished_count - failed_count
+                    add_activity_item("✅", "Download Batch Complete", f"'{playlist_name}' - {successful_downloads} tracks downloaded", "Now")
+
+                    # Emit batch_complete event for automation engine
+                    try:
+                        if automation_engine:
+                            automation_engine.emit('batch_complete', {
+                                'playlist_name': playlist_name,
+                                'total_tracks': str(len(queue)),
+                                'completed_tracks': str(successful_downloads),
+                                'failed_tracks': str(failed_count),
+                            })
+                    except Exception:
+                        pass
                 else:
                     print(f"✅ [Completion Check V2] Batch {batch_id} already marked complete - skipping duplicate processing")
                     return True  # Already complete