YetiBrowser MCP

#!/usr/bin/env node import { StreamableHTTPServerTransport } from "@modelcontextprotocol/sdk/server/streamableHttp.js"; import { StdioServerTransport } from "@modelcontextprotocol/sdk/server/stdio.js"; import { Command, InvalidArgumentError } from "commander"; import { randomUUID } from "node:crypto"; import { once } from "node:events"; import { createServer } from "node:http"; import { createRequire } from "node:module"; const require = createRequire(import.meta.url); const packageJson = require("../package.json") as { version: string }; import { ExtensionBridge } from "./bridge.js"; import { createMcpServer } from "./server.js"; const AUTO_WS_PORTS = [9010, 9011, 9012, 9013, 9014, 9015, 9016, 9017, 9018, 9019, 9020]; function parsePort(value: string): number { const port = Number(value); if (!Number.isInteger(port) || port <= 0 || port > 65535) { throw new InvalidArgumentError("Port must be an integer between 1 and 65535"); } return port; } function buildPortCandidates(preferred: number): number[] { const index = AUTO_WS_PORTS.indexOf(preferred); if (index === -1) { return [preferred]; } return [...AUTO_WS_PORTS.slice(index), ...AUTO_WS_PORTS.slice(0, index)]; } async function startBridgeWithFallback(portCandidates: number[]): Promise<{ bridge: ExtensionBridge; port: number }> { let lastError: unknown; for (const candidatePort of portCandidates) { const candidateBridge = new ExtensionBridge({ port: candidatePort }); try { await candidateBridge.start(); if (candidatePort !== portCandidates[0]) { console.error(`[yetibrowser] WebSocket port ${portCandidates[0]} busy, switched to ${candidatePort}`); } return { bridge: candidateBridge, port: candidatePort }; } catch (error) { lastError = error; await candidateBridge.close().catch(() => { /* ignore */ }); if (error instanceof Error && error.message.includes("already in use")) { continue; } const message = error instanceof Error ? error.message : String(error); console.error(`[yetibrowser] Failed to start WebSocket bridge: ${message}`); process.exit(1); } } const message = lastError instanceof Error ? lastError.message : String(lastError ?? "unknown error"); console.error(`[yetibrowser] Failed to find available WebSocket port near ${portCandidates[0]}: ${message}`); process.exit(1); } const program = new Command(); program .name("yetibrowser-mcp") .version(packageJson.version) .description("YetiBrowser MCP server") .option( "--ws-port <port>", "WebSocket port exposed for the browser extension", parsePort, 9010, ) .option( "--http-port <port>", "Optional Streamable HTTP endpoint for sharing the server across multiple MCP clients", parsePort, ) .action( async ({ wsPort, httpPort }: { wsPort: number; httpPort?: number }) => { const portCandidates = buildPortCandidates(wsPort); const { bridge, port: activeWsPort } = await startBridgeWithFallback(portCandidates); wsPort = activeWsPort; const server = await createMcpServer({ name: "YetiBrowser MCP", version: packageJson.version, bridge, }); let httpServer: ReturnType<typeof createServer> | undefined; let httpTransport: StreamableHTTPServerTransport | undefined; let stdioTransport: StdioServerTransport | undefined; let shuttingDown = false; const shutdown = async () => { if (shuttingDown) { return; } shuttingDown = true; console.error("[yetibrowser] shutting down"); const tasks: Array<Promise<unknown>> = [server.close(), bridge.close()]; if (httpTransport) { tasks.push(httpTransport.close()); } if (httpServer) { tasks.push( new Promise<void>((resolve) => { httpServer!.close(() => resolve()); }), ); } if (stdioTransport) { tasks.push(stdioTransport.close()); } await Promise.allSettled(tasks); process.exit(0); }; process.on("SIGINT", shutdown); process.on("SIGTERM", shutdown); if (httpPort !== undefined) { httpTransport = new StreamableHTTPServerTransport({ sessionIdGenerator: () => randomUUID(), enableJsonResponse: true, }); httpTransport.onerror = (error) => { console.error("[yetibrowser] HTTP transport error", error); }; await server.connect(httpTransport); httpServer = createServer(async (req, res) => { try { if (!req.url) { res.writeHead(400).end("Missing request URL"); return; } const requestUrl = new URL(req.url, `http://${req.headers.host ?? `localhost:${httpPort}`}`); if (requestUrl.pathname !== "/mcp") { res.writeHead(404).end("Not Found"); return; } const acceptHeader = req.headers.accept; if (typeof acceptHeader === "string") { const parts = acceptHeader.split(",").map((value) => value.trim()); if (!parts.includes("text/event-stream")) { parts.push("text/event-stream"); } if (!parts.includes("application/json")) { parts.unshift("application/json"); } req.headers.accept = parts.join(", "); } else if (Array.isArray(acceptHeader)) { const headerValues = acceptHeader as string[]; const combined = headerValues.join(","); const entries = combined .split(",") .map((entry: string) => entry.trim()) .filter((entry: string) => entry.length > 0); const parts = new Set(entries); parts.add("application/json"); parts.add("text/event-stream"); req.headers.accept = Array.from(parts).join(", "); } else { req.headers.accept = "application/json, text/event-stream"; } await httpTransport!.handleRequest(req, res); } catch (error) { console.error("[yetibrowser] Failed to handle HTTP request", error); if (!res.headersSent) { res.writeHead(500).end("Internal Server Error"); } else { res.end(); } } }); const listenPromise = Promise.race([ once(httpServer, "listening"), once(httpServer, "error").then(([error]) => { throw error; }), ]); httpServer.listen(httpPort, "127.0.0.1"); try { await listenPromise; } catch (error) { const err = error as NodeJS.ErrnoException; if (err?.code === "EADDRINUSE") { console.error( `[yetibrowser] Failed to start HTTP transport: port ${httpPort} is already in use. Pick a different --http-port value.`, ); } else { console.error("[yetibrowser] Failed to start HTTP transport", err); } await shutdown(); return; } console.error(`[yetibrowser] Streamable HTTP endpoint ready at http://127.0.0.1:${httpPort}/mcp`); process.stdin.on("close", shutdown); } else { stdioTransport = new StdioServerTransport(); await server.connect(stdioTransport); process.stdin.on("close", shutdown); } }, ); program.parse();