构建深度研究代理

mkdir deep-research-agent
cd deep-research-agent

import { tool } from "langchain";
import { z } from "zod";

async function fetchWebpageContent(
  url: string,
  timeout = 10_000,
): Promise<string> {
  try {
    const controller = new AbortController();
    const id = setTimeout(() => controller.abort(), timeout);
    const response = await fetch(url, {
      headers: {
        "User-Agent":
          "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36",
      },
      signal: controller.signal,
    });
    clearTimeout(id);
    if (!response.ok) {
      return `Error fetching ${url}: HTTP ${response.status}`;
    }
    return await response.text();
  } catch (e) {
    return `Error fetching ${url}: ${e}`;
  }
}

const tavilySearch = tool(
  async ({
    query,
    maxResults = 1,
    topic = "general",
  }: {
    query: string;
    maxResults?: number;
    topic?: "general" | "news" | "finance";
  }) => {
    const response = await fetch("https://api.tavily.com/search", {
      method: "POST",
      headers: {
        "Content-Type": "application/json",
        Authorization: `Bearer ${process.env.TAVILY_API_KEY}`,
      },
      body: JSON.stringify({ query, max_results: maxResults, topic }),
    });
    const data = (await response.json()) as {
      results: Array<{ url: string; title: string }>;
    };
    const results = data.results ?? [];
    const resultTexts: string[] = [];
    for (const result of results) {
      const content = await fetchWebpageContent(result.url);
      resultTexts.push(
        `## ${result.title}\n**URL:** ${result.url}\n\n${content}\n---`,
      );
    }
    return (
      `Found ${resultTexts.length} result(s) for '${query}':\n\n` +
      resultTexts.join("\n")
    );
  },
  {
    name: "tavily_search",
    description:
      "Search the web for information on a given query. Uses Tavily to discover relevant URLs, then fetches and returns full webpage content.",
    schema: z.object({
      query: z.string().describe("Search query to execute"),
      maxResults: z
        .number()
        .optional()
        .default(1)
        .describe("Maximum number of results to return (default: 1)"),
      topic: z
        .enum(["general", "news", "finance"])
        .optional()
        .default("general")
        .describe(
          "Topic filter - 'general', 'news', or 'finance' (default: 'general')",
        ),
    }),
  },
);

import { todoListMiddleware } from "langchain";

import { createDeepAgent } from "deepagents";
import { ChatAnthropic } from "@langchain/anthropic";
import { todoListMiddleware } from "langchain";

// 最大并发研究单元数量
const maxConcurrentResearchUnits = 3;
// 研究员最大迭代次数
const maxResearcherIterations = 3;

// 获取当前日期
const currentDate = new Date().toISOString().split("T")[0];

// 构造系统指令
const INSTRUCTIONS =
  RESEARCH_WORKFLOW_INSTRUCTIONS +
  "\n\n" +
  "=".repeat(80) +
  "\n\n" +
  SUBAGENT_DELEGATION_INSTRUCTIONS.replace(
    "{maxConcurrentResearchUnits}",
    String(maxConcurrentResearchUnits),
  ).replace("{maxResearcherIterations}", String(maxResearcherIterations));

// 定义研究子代理
const researchSubAgent = {
  name: "research-agent",
  description: "将研究工作委派给子代理。每次给出一个主题。",
  systemPrompt: RESEARCHER_INSTRUCTIONS.replace("{date}", currentDate),
  tools: [tavilySearch],
};

// 初始化语言模型
const model = new ChatAnthropic({
  model: "claude-sonnet-4-5-20250929",
  temperature: 0,
});

// 创建深度代理实例
const agent = await createDeepAgent({
  model,
  tools: [tavilySearch],
  systemPrompt: INSTRUCTIONS,
  subagents: [researchSubAgent],
  middleware: [todoListMiddleware()],
});