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"""
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智能搜索助手 - 基于 LangGraph + Tavily API 的真实搜索系统
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1. 理解用户需求
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2. 使用Tavily API真实搜索信息
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3. 生成基于搜索结果的回答
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"""
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import asyncio
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from typing import TypedDict, Annotated
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from langchain_core.messages import HumanMessage, AIMessage, SystemMessage
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from langchain_openai import ChatOpenAI
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from langgraph.graph import StateGraph, START, END
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from langgraph.graph.message import add_messages
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from langgraph.checkpoint.memory import InMemorySaver
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import os
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from dotenv import load_dotenv
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from tavily import TavilyClient
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# 加载环境变量
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load_dotenv()
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# 定义状态结构
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class SearchState(TypedDict):
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messages: Annotated[list, add_messages]
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user_query: str # 用户查询
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search_query: str # 优化后的搜索查询
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search_results: str # Tavily搜索结果
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final_answer: str # 最终答案
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step: str # 当前步骤
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# 初始化模型和Tavily客户端
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llm = ChatOpenAI(
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model=os.getenv("LLM_MODEL_ID", "gpt-4o-mini"),
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api_key=os.getenv("LLM_API_KEY"),
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base_url=os.getenv("LLM_BASE_URL", "https://api.openai.com/v1"),
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temperature=0.7
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)
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# 初始化Tavily客户端
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tavily_client = TavilyClient(api_key=os.getenv("TAVILY_API_KEY"))
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def understand_query_node(state: SearchState) -> SearchState:
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"""步骤1：理解用户查询并生成搜索关键词"""
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# 获取最新的用户消息
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user_message = ""
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for msg in reversed(state["messages"]):
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if isinstance(msg, HumanMessage):
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user_message = msg.content
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break
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understand_prompt = f"""分析用户的查询："{user_message}"
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请完成两个任务：
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1. 简洁总结用户想要了解什么
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2. 生成最适合搜索的关键词（中英文均可，要精准）
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格式：
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理解：[用户需求总结]
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搜索词：[最佳搜索关键词]"""
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response = llm.invoke([SystemMessage(content=understand_prompt)])
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# 提取搜索关键词
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response_text = response.content
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search_query = user_message # 默认使用原始查询
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if "搜索词：" in response_text:
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search_query = response_text.split("搜索词：")[1].strip()
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elif "搜索关键词：" in response_text:
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search_query = response_text.split("搜索关键词：")[1].strip()
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return {
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"user_query": response.content,
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"search_query": search_query,
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"step": "understood",
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"messages": [AIMessage(content=f"我理解您的需求：{response.content}")]
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}
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def tavily_search_node(state: SearchState) -> SearchState:
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"""步骤2：使用Tavily API进行真实搜索"""
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search_query = state["search_query"]
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try:
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print(f"🔍 正在搜索: {search_query}")
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# 调用Tavily搜索API
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response = tavily_client.search(
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query=search_query,
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search_depth="basic",
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include_answer=True,
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include_raw_content=False,
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max_results=5
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)
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# 处理搜索结果
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search_results = ""
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# 优先使用Tavily的综合答案
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if response.get("answer"):
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search_results = f"综合答案：\n{response['answer']}\n\n"
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# 添加具体的搜索结果
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if response.get("results"):
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search_results += "相关信息：\n"
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for i, result in enumerate(response["results"][:3], 1):
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title = result.get("title", "")
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content = result.get("content", "")
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url = result.get("url", "")
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search_results += f"{i}. {title}\n{content}\n来源：{url}\n\n"
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if not search_results:
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search_results = "抱歉，没有找到相关信息。"
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return {
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"search_results": search_results,
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"step": "searched",
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"messages": [AIMessage(content=f"✅ 搜索完成！找到了相关信息，正在为您整理答案...")]
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}
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except Exception as e:
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error_msg = f"搜索时发生错误: {str(e)}"
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print(f"❌ {error_msg}")
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return {
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"search_results": f"搜索失败：{error_msg}",
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"step": "search_failed",
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"messages": [AIMessage(content="❌ 搜索遇到问题，我将基于已有知识为您回答")]
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}
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def generate_answer_node(state: SearchState) -> SearchState:
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"""步骤3：基于搜索结果生成最终答案"""
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# 检查是否有搜索结果
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if state["step"] == "search_failed":
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# 如果搜索失败，基于LLM知识回答
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fallback_prompt = f"""搜索API暂时不可用，请基于您的知识回答用户的问题：
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用户问题：{state['user_query']}
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请提供一个有用的回答，并说明这是基于已有知识的回答。"""
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response = llm.invoke([SystemMessage(content=fallback_prompt)])
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return {
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"final_answer": response.content,
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"step": "completed",
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"messages": [AIMessage(content=response.content)]
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}
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# 基于搜索结果生成答案
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answer_prompt = f"""基于以下搜索结果为用户提供完整、准确的答案：
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用户问题：{state['user_query']}
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搜索结果：
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{state['search_results']}
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请要求：
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1. 综合搜索结果，提供准确、有用的回答
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2. 如果是技术问题，提供具体的解决方案或代码
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3. 引用重要信息的来源
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4. 回答要结构清晰、易于理解
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5. 如果搜索结果不够完整，请说明并提供补充建议"""
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response = llm.invoke([SystemMessage(content=answer_prompt)])
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return {
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"final_answer": response.content,
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"step": "completed",
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"messages": [AIMessage(content=response.content)]
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}
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# 构建搜索工作流
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def create_search_assistant():
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workflow = StateGraph(SearchState)
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# 添加三个节点
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workflow.add_node("understand", understand_query_node)
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workflow.add_node("search", tavily_search_node)
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workflow.add_node("answer", generate_answer_node)
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# 设置线性流程
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workflow.add_edge(START, "understand")
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workflow.add_edge("understand", "search")
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workflow.add_edge("search", "answer")
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workflow.add_edge("answer", END)
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# 编译图
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memory = InMemorySaver()
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app = workflow.compile(checkpointer=memory)
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return app
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async def main():
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"""主函数：运行智能搜索助手"""
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# 检查API密钥
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if not os.getenv("TAVILY_API_KEY"):
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print("❌ 错误：请在.env文件中配置TAVILY_API_KEY")
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return
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app = create_search_assistant()
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print("🔍 智能搜索助手启动！")
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print("我会使用Tavily API为您搜索最新、最准确的信息")
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print("支持各种问题：新闻、技术、知识问答等")
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print("(输入 'quit' 退出)\n")
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session_count = 0
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while True:
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user_input = input("🤔 您想了解什么: ").strip()
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if user_input.lower() in ['quit', 'q', '退出', 'exit']:
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print("感谢使用！再见！👋")
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break
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if not user_input:
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continue
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session_count += 1
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config = {"configurable": {"thread_id": f"search-session-{session_count}"}}
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# 初始状态
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initial_state = {
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"messages": [HumanMessage(content=user_input)],
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"user_query": "",
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"search_query": "",
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"search_results": "",
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"final_answer": "",
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"step": "start"
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}
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try:
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print("\n" + "="*60)
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# 执行工作流
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async for output in app.astream(initial_state, config=config):
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for node_name, node_output in output.items():
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if "messages" in node_output and node_output["messages"]:
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latest_message = node_output["messages"][-1]
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if isinstance(latest_message, AIMessage):
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if node_name == "understand":
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print(f"🧠 理解阶段: {latest_message.content}")
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elif node_name == "search":
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print(f"🔍 搜索阶段: {latest_message.content}")
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elif node_name == "answer":
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print(f"\n💡 最终回答:\n{latest_message.content}")
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print("\n" + "="*60 + "\n")
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except Exception as e:
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print(f"❌ 发生错误: {e}")
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print("请重新输入您的问题。\n")
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if __name__ == "__main__":
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asyncio.run(main())
|
