Hugging Face MCP Server

import { StatefulTransport, type TransportOptions, type BaseSession } from './base-transport.js'; import { StdioServerTransport } from '@modelcontextprotocol/sdk/server/stdio.js'; import { logger } from '../utils/logger.js'; type StdioSession = BaseSession<StdioServerTransport>; /** * Implementation of STDIO transport */ export class StdioTransport extends StatefulTransport<StdioSession> { private readonly SESSION_ID = 'STDIO'; async initialize(_options: TransportOptions): Promise<void> { const transport = new StdioServerTransport(); // Create server instance using factory (null headers for STDIO) const result = await this.serverFactory(null); const server = result.server; // Create session with metadata tracking const session: StdioSession = { transport, server, metadata: { id: this.SESSION_ID, connectedAt: new Date(), lastActivity: new Date(), requestCount: 0, isAuthenticated: false, // STDIO doesn't have authentication headers capabilities: {}, }, }; // Store session in map this.sessions.set(this.SESSION_ID, session); // Track the session creation for metrics this.trackSessionCreated(this.SESSION_ID); try { // Set up request/response interceptors for metrics const originalSendMessage = transport.send.bind(transport); transport.send = (message) => { this.trackRequest(); this.updateSessionActivity(this.SESSION_ID); // Increment request count const session = this.sessions.get(this.SESSION_ID); if (session) { session.metadata.requestCount++; } return originalSendMessage(message); }; // Set up oninitialized callback to capture client info using base class helper server.server.oninitialized = this.createClientInfoCapture(this.SESSION_ID); // Set up error tracking server.server.onerror = (error) => { this.trackError(undefined, error); logger.error({ error }, 'STDIO server error'); }; await server.connect(transport); logger.info('STDIO transport initialized'); } catch (error) { logger.error({ error }, 'Error connecting STDIO transport'); // Clean up on error const session = this.sessions.get(this.SESSION_ID); this.sessions.delete(this.SESSION_ID); this.trackSessionCleaned(session); throw error; } } /** * STDIO doesn't need stale session removal since there's only one persistent session */ protected removeStaleSession(sessionId: string): Promise<void> { // STDIO has only one session and it's not subject to staleness logger.debug({ sessionId }, 'STDIO session staleness check (no-op)'); return Promise.resolve(); } async cleanup(): Promise<void> { const session = this.sessions.get(this.SESSION_ID); if (session) { try { await session.transport.close(); } catch (error) { logger.error({ error }, 'Error closing STDIO transport'); } try { await session.server.close(); } catch (error) { logger.error({ error }, 'Error closing STDIO server'); } // Track session cleanup for metrics this.trackSessionCleaned(session); } this.sessions.clear(); logger.info('STDIO transport cleaned up'); return Promise.resolve(); } /** * Get the STDIO session if it exists */ getSession(): StdioSession | undefined { return this.sessions.get(this.SESSION_ID); } }