diff --git a/routes/chat.py b/routes/chat.py
index 06dd624..40d0f82 100644
--- a/routes/chat.py
+++ b/routes/chat.py
@@ -191,6 +191,8 @@ async def enhanced_generate_stream_response(
                 if all(task.done() for task in [preamble_task_handle, agent_task_handle]):
                     # 所有任务都完成了，退出循环
                     break
+                # 发送 SSE 心跳注释保持连接活跃，防止 nginx/客户端超时断开
+                yield ": heartbeat\n\n"
                 continue
 
         # 发送结束标记