修复checkpoint_id 偶发获取不到

src/routers/deep_agent_chat.py

@@ -187,8 +187,9 @@ async def chat_stream(request: DeepAgentChatRequest):
                 stream_mode=["updates", "messages", "custom"],
                 subgraphs=True
         ):
+            _, mode, chunks = stream
             if is_first:
-                checkpoint_id = main_agent.get_state(current_config).config.get("configurable").get("checkpoint_id")
+                checkpoint_id = get_latest_checkpoint_id(main_agent, current_config)
                 if not checkpoint_id:
                     print("123")
                 main_agent.store.put(
@@ -202,7 +203,6 @@ async def chat_stream(request: DeepAgentChatRequest):
                 logger.info(f"*******************{checkpoint_id}**********************************")
                 yield f"data: {json.dumps({'thread_id': target_thread_id, 'is_branch': is_branching, 'status': 'start', "checkpoint_id": checkpoint_id}, ensure_ascii=False)}\n\n"
                 is_first = False
-            _, mode, chunks = stream
             if mode == "updates":  # 只做记录 不做事件返回
                 logger.info(f"[updates] -- {chunks}")
 
@@ -424,3 +424,22 @@ async def get_branch_checkpoint_id(main_agent, current_config):
                 return item.config.get('configurable', {}).get('checkpoint_id')
     # 没找到
     return None
+
+
+def get_latest_checkpoint_id(agent, config):
+    # 先尝试直接 get_state
+    state = agent.get_state(config)
+    checkpoint_id = state.config.get("configurable", {}).get("checkpoint_id")
+
+    if checkpoint_id:
+        return checkpoint_id
+
+    # 如果是 None 或空，使用 history 取最新一条（history[0] 永远是最新的）
+    print("checkpoint_id 为 None，使用 get_state_history 兜底...")
+    history = list(agent.get_state_history(config))
+    if history:
+        checkpoint_id = history[0].config["configurable"]["checkpoint_id"]
+        print(f"从 history 获取到最新 checkpoint_id: {checkpoint_id}")
+        return checkpoint_id
+
+    return None