diff --git a/app/routers/chatbot.py b/app/routers/chatbot.py
index 4bb2e88..693d7dc 100644
--- a/app/routers/chatbot.py
+++ b/app/routers/chatbot.py
@@ -355,7 +355,8 @@ async def _handle_wechat_request(request: Request, app_id: Optional[str], backgr
         response_app_id = str(data.get("ChannelId", "") or data.get("appid", "")).strip() or APP_ID
     else:
         resp_plain = json.dumps({"answer_type": "text", "text_info": {"short_answer": answer_text}}, ensure_ascii=False)
-        response_app_id = None if app_id else APP_ID
+        # thirdapi 场景也要携带 app_id 参与加密，否则平台可能判定回包无效
+        response_app_id = (app_id or APP_ID).strip() if isinstance(app_id, str) else APP_ID
 
     return aes_encrypt_base64(resp_plain, ENCODING_AES_KEY, response_app_id)