update app.py

app.py

@@ -156,6 +156,11 @@ def get_reference_portraits(story_id: str) -> List[Tuple[str, str]]:
 _save_lock = threading.Lock()
 
 
+def _get_lock():
+    """Return the scheduler lock if available, otherwise use the local lock."""
+    return scheduler.lock if scheduler is not None else _save_lock
+
+
 # ============================================================================
 # Group Management
 # ============================================================================
@@ -241,7 +246,7 @@ def create_group_config(group_id: str) -> Dict[str, Any]:
         "method_display_map": method_display_map,
     }
 
-    with _save_lock:
+    with _get_lock():
         with open(group_dir / "mapping.json", "w", encoding="utf-8") as f:
             json.dump(config, f, indent=2, ensure_ascii=False)
 
@@ -272,7 +277,7 @@ def save_ranking_result(
     }
 
     filepath = story_dir / filename
-    with _save_lock:
+    with _get_lock():
         story_dir.mkdir(parents=True, exist_ok=True)
         with open(filepath, "w", encoding="utf-8") as f:
             json.dump(result_data, f, indent=4, ensure_ascii=False)