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while True:
    response = client.chat.completions.create(messages=messages, tools=tools)
    messages.append(response.choices[0].message)

    if not response.choices[0].message.tool_calls:
        break

    for tc in response.choices[0].message.tool_calls:
        result = dispatch(tc)
        messages.append(result)

1

pip install langgraph langchain-openai

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from typing import Annotated, TypedDict

from langgraph.graph import StateGraph, START, END
from langgraph.graph.message import add_messages
from langgraph.checkpoint.memory import InMemorySaver
from langchain_openai import ChatOpenAI
from langchain_core.messages import HumanMessage, ToolMessage

# ===== 工具函数：和第三篇一模一样 =====
def get_weather(city: str) -> str:
    return f"{city}今天晴，25度"

def get_aqi(city: str) -> str:
    return f"{city}AQI 50，优"

tool_map = {"get_weather": get_weather, "get_aqi": get_aqi}

# ===== 工具 schema：手写 JSON，不用装饰器 =====
tools = [
    {"type": "function", "function": {
        "name": "get_weather",
        "description": "查询城市天气",
        "parameters": {"type": "object",
            "properties": {"city": {"type": "string"}},
            "required": ["city"]}
    }},
    {"type": "function", "function": {
        "name": "get_aqi",
        "description": "查询城市空气质量",
        "parameters": {"type": "object",
            "properties": {"city": {"type": "string"}},
            "required": ["city"]}
    }},
]

# ===== State：就是你的 messages =====
class AgentState(TypedDict):
    messages: Annotated[list, add_messages]

# ===== 节点1：调模型 =====
model = ChatOpenAI(model="deepseek-v4-flash", api_key="你的DeepSeek API Key", base_url="https://api.deepseek.com")
model_with_tools = model.bind_tools(tools)

def agent_node(state: AgentState):
    response = model_with_tools.invoke(state["messages"])
    return {"messages": [response]}

# ===== 节点2：执行工具 =====
def tools_node(state: AgentState):
    last = state["messages"][-1]
    results = []
    for tc in last.tool_calls:
        try:
            result = tool_map[tc.name](**tc.args)
        except Exception as e:
            result = f"工具调用失败: {e}"
        results.append(ToolMessage(content=result, tool_call_id=tc.id))
    return {"messages": results}

# ===== 条件边：有 tool_calls 去 tools，否则结束 =====
def should_continue(state: AgentState):
    last = state["messages"][-1]
    if last.tool_calls:
        return "tools"
    return END

# ===== 拼图 =====
builder = StateGraph(AgentState)
builder.add_node("agent", agent_node)
builder.add_node("tools", tools_node)
builder.add_edge(START, "agent")
builder.add_conditional_edges("agent", should_continue, {"tools": "tools", END: END})
builder.add_edge("tools", "agent")

# ===== 加 checkpointer =====
checkpointer = InMemorySaver()
graph = builder.compile(checkpointer=checkpointer)

# ===== 跑起来 =====
config = {"configurable": {"thread_id": "user-001"}}

graph.invoke({"messages": [HumanMessage(content="北京天气怎么样？")]}, config)
graph.invoke({"messages": [HumanMessage(content="那空气质量呢？")]}, config)