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julien-c/lightpanda-mcp.ts

Created April 4, 2025 21:59
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  1. julien-c created this gist Apr 4, 2025.
    190 changes: 190 additions & 0 deletions lightpanda-mcp.ts
    View file
    Original file line number Diff line number Diff line change
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    import { McpServer } from "@modelcontextprotocol/sdk/server/mcp.js";
    import { StdioServerTransport } from "@modelcontextprotocol/sdk/server/stdio.js";
    import { z } from "zod";
    import { spawn } from "node:child_process";
    import puppeteer, { Browser, BrowserContext, Page } from "puppeteer-core";
    import { fileURLToPath } from "url";
    import { dirname } from "path";
    import { setTimeout } from "node:timers/promises";

    const LIGHTPANDA_PORT = 9222;
    const DEV = false;
    const c = console;

    const __dirname = dirname(fileURLToPath(import.meta.url));

    const lightpanda = spawn("./lightpanda", ["serve", "--port", `${LIGHTPANDA_PORT}`], { cwd: __dirname });

    lightpanda.stdout.on("data", data => {
    if (DEV) {
    c.log(`[panda] stdout: ${data}`);
    }
    });
    lightpanda.stderr.on("data", data => {
    if (DEV) {
    c.error(`[panda] stderr: ${data}`);
    }
    });
    lightpanda.on("close", code => {
    if (DEV) {
    c.log(`[panda] child process exited with code ${code}`);
    }
    });
    const cleanupLp = () => {
    lightpanda.kill();
    process.exit();
    };
    process.on("exit", cleanupLp);
    process.on("SIGINT", cleanupLp);
    process.on("SIGTERM", cleanupLp);
    process.on("SIGQUIT", cleanupLp);

    let browser: Browser | undefined;
    let context: BrowserContext | undefined;
    let page: Page | undefined;

    // Create server instance
    const server = new McpServer({
    name: "lightpanda",
    version: "1.0.0",
    capabilities: {
    tools: {},
    },
    });

    server.tool(
    "navigate",
    "Navigate to a URL and return the full raw HTML",
    {
    url: z.string().url().describe("URL to navigate to"),
    },
    async ({ url }) => {
    if (!browser || !browser.connected) {
    browser = await puppeteer.connect({
    browserWSEndpoint: `ws://127.0.0.1:${LIGHTPANDA_PORT}`,
    });
    context = undefined;
    }
    if (!context || !context.browser().connected) {
    context = await browser.createBrowserContext();
    }
    try {
    page = await context.newPage();
    await page.goto(url, { waitUntil: "load" });
    const html = await page.content();
    return {
    content: [
    {
    type: "text",
    text: html,
    },
    ],
    };
    } catch (err) {
    return {
    content: [
    {
    type: "text",
    text: `Error: ${err}`,
    },
    ],
    };
    }
    }
    );

    server.tool("get_all_links", "Get all links from the webpage", {}, async () => {
    if (!page) {
    return {
    isError: true,
    content: [
    {
    type: "text",
    text: `The browser does not have a page currently open, first navigate to a page`,
    },
    ],
    };
    }
    try {
    const links = await page.evaluate(() => {
    return Array.from(document.querySelectorAll("a")).map(row => {
    return row.getAttribute("href");
    });
    });
    return {
    content: [
    {
    type: "text",
    text: links.join("\n"),
    },
    ],
    };
    } catch (err) {
    return {
    content: [
    {
    type: "text",
    text: `Error: ${err}`,
    },
    ],
    };
    }
    });

    server.tool(
    "read_text",
    "Read inner text of a specific DOM element inside the webpage",
    {
    selector: z.string().describe("CSS selector for element to read"),
    },
    async ({ selector }) => {
    if (!page) {
    return {
    isError: true,
    content: [
    {
    type: "text",
    text: `The browser does not have a page currently open, first navigate to a page`,
    },
    ],
    };
    }
    try {
    const content = await page.evaluate(() => {
    return document.querySelector(selector)?.textContent;
    });
    return {
    content: [
    {
    type: "text",
    text: content ?? "no content found",
    },
    ],
    };
    } catch (err) {
    return {
    content: [
    {
    type: "text",
    text: `Error: ${err}`,
    },
    ],
    };
    }
    }
    );

    async function main() {
    await setTimeout(500);
    browser = await puppeteer.connect({
    browserWSEndpoint: `ws://127.0.0.1:${LIGHTPANDA_PORT}`,
    });

    const transport = new StdioServerTransport();
    await server.connect(transport);
    }

    main().catch(error => {
    console.error("Fatal error in main():", error);
    process.exit(1);
    });