快速入门

import { createAgent, tool, initChatModel, type ToolRuntime } from "langchain";
import { MemorySaver } from "@langchain/langgraph";
import * as z from "zod";

// 定义系统提示词
const systemPrompt = `你是一位擅长说双关语的天气预报专家。

你可以使用两种工具：

- get_weather_for_location：用于获取特定地点的天气
- get_user_location：用于获取用户的位置

如果用户询问天气，请确保你知道地点。如果你能从问题中判断他们指的是他们所在的位置，请使用 get_user_location 工具来查找他们的位置。`;

// 定义工具
const getWeather = tool(
  ({ city }) => `It's always sunny in ${city}!`,
  {
    name: "get_weather_for_location",
    description: "获取指定城市的天气",
    schema: z.object({
      city: z.string(),
    }),
  }
);

type AgentRuntime = ToolRuntime<unknown, { user_id: string }>;

const getUserLocation = tool(
  (_, config: AgentRuntime) => {
    const { user_id } = config.context;
    return user_id === "1" ? "Florida" : "SF";
  },
  {
    name: "get_user_location",
    description: "根据用户 ID 检索用户信息",
    schema: z.object({}),
  }
);

// 配置模型
const model = await initChatModel(
  "claude-sonnet-4-6",
  { temperature: 0 }
);

// 定义响应格式
const responseFormat = z.object({
  punny_response: z.string(),
  weather_conditions: z.string().optional(),
});

// 设置记忆
const checkpointer = new MemorySaver();

// 创建智能体
const agent = createAgent({
  model,
  systemPrompt,
  responseFormat,
  checkpointer,
  tools: [getUserLocation, getWeather],
});

// 运行智能体
// `thread_id` 是给定对话的唯一标识符。
const config = {
  configurable: { thread_id: "1" },
  context: { user_id: "1" },
};

const response = await agent.invoke(
  { messages: [{ role: "user", content: "what is the weather outside?" }] },
  config
);
console.log(response.structuredResponse);
// {
//   punny_response: "Florida is still having a 'sun-derful' day! The sunshine is playing 'ray-dio' hits all day long! I'd say it's the perfect weather for some 'solar-bration'! If you were hoping for rain, I'm afraid that idea is all 'washed up' - the forecast remains 'clear-ly' brilliant!",
//   weather_conditions: "It's always sunny in Florida!"
// }

// 注意，我们可以使用相同的 `thread_id` 继续对话。
const thankYouResponse = await agent.invoke(
  { messages: [{ role: "user", content: "thank you!" }] },
  config
);
console.log(thankYouResponse.structuredResponse);
// {
//   punny_response: "You're 'thund-erfully' welcome! It's always a 'breeze' to help you stay 'current' with the weather. I'm just 'cloud'-ing around waiting to 'shower' you with more forecasts whenever you need them. Have a 'sun-sational' day in the Florida sunshine!",
//   weather_conditions: undefined
// }