feat: 通过判断langgraph_node以及消息是AIMessage还是ToolMessage，如果是AIMessage就跳过的方式来规避这个问题

app/controller/add_langgraph_chat_route.py

@@ -3,7 +3,7 @@ import time
 from typing import Union
 
 from fastapi import FastAPI
-from langchain_core.messages import AIMessage, ToolMessage
+from langchain_core.messages import AIMessage, ToolMessage, AIMessageChunk
 from langgraph.graph.state import CompiledStateGraph
 from langgraph.prebuilt import create_react_agent
 from langgraph.types import Command
@@ -122,6 +122,14 @@ def add_langgraph_chat_route(app: FastAPI):
         emit_chunk = {"stream_type": chunk[0], }
 
         if emit_chunk['stream_type'] == "messages":
+
+          if isinstance(chunk[1], tuple):
+            if isinstance(chunk[1][1], dict):
+              langgraph_node = chunk[1][1].get("langgraph_node")
+              if langgraph_node == "tools" and isinstance(chunk[1][0], AIMessage):
+                print("忽略工具中的message消息")
+                continue
+
           # messages模式流式输出，此时 chunk[1][0] 为AIMessageChunk
           chunk_message = chunk[1][0]
           if not chunk_message.content: