diff --git a/src/core/message_handler.py b/src/core/message_handler.py
index 750ab7e..9a86c24 100644
--- a/src/core/message_handler.py
+++ b/src/core/message_handler.py
@@ -47,7 +47,7 @@ class MessageHandler:
         return None
 
     async def fetch_group_messages(
-        self, bot_instance, group_id: str, days: int
+        self, bot_instance, group_id: str, days: int, platform_id: str = None
     ) -> List[Dict]:
         """获取群聊消息记录"""
         try:
diff --git a/src/scheduler/auto_scheduler.py b/src/scheduler/auto_scheduler.py
index bb848cb..2b140a2 100644
--- a/src/scheduler/auto_scheduler.py
+++ b/src/scheduler/auto_scheduler.py
@@ -79,12 +79,12 @@ class AutoScheduler:
                 logger.warning(f"使用默认平台: {first_platform}")
                 return first_platform
             
-            # 回退到默认值
-            logger.warning(f"⚠️ 没有注册的bot实例，使用默认平台 'default'")
-            return "default"
+            # 没有任何bot实例，返回None
+            logger.error(f"❌ 没有注册的bot实例")
+            return None
         except Exception as e:
             logger.error(f"❌ 获取平台ID失败: {e}")
-            return "default"
+            return None
 
     async def start_scheduler(self):
         """启动定时任务调度器"""