Hugging Face MCP Server

import { type Express } from 'express'; import { type TransportType } from '../shared/constants.js'; import type { TransportInfo } from '../shared/transport-info.js'; import { createTransport } from './transport/transport-factory.js'; import type { BaseTransport, ServerFactory } from './transport/base-transport.js'; import type { WebServer } from './web-server.js'; import { logger } from './utils/logger.js'; import { createServerFactory } from './mcp-server.js'; import { createProxyServerFactory } from './mcp-proxy.js'; import { McpApiClient, type ApiClientConfig, type GradioEndpoint } from './utils/mcp-api-client.js'; import { DEFAULT_SPACE_TOOLS, type SpaceTool } from '../shared/settings.js'; export interface ApplicationOptions { transportType: TransportType; webAppPort: number; webServerInstance: WebServer; apiClientConfig?: ApiClientConfig; // Optional - defaults to polling mode } /** * Main application class that coordinates web server, MCP server factory, and transport lifecycle */ export class Application { private serverFactory: ServerFactory; private webServerInstance: WebServer; private appInstance: Express; private transport?: BaseTransport; private apiClient: McpApiClient; private transportType: TransportType; private webAppPort: number; private isDev: boolean; constructor(options: ApplicationOptions) { this.transportType = options.transportType; this.webAppPort = options.webAppPort; this.webServerInstance = options.webServerInstance; this.isDev = process.env.NODE_ENV === 'development'; // Create transport info first const defaultHfToken = process.env.DEFAULT_HF_TOKEN; const transportInfo: TransportInfo = { transport: this.transportType, port: this.webAppPort, defaultHfTokenSet: !!defaultHfToken, hfTokenMasked: defaultHfToken ? maskToken(defaultHfToken) : undefined, jsonResponseEnabled: this.transportType === 'streamableHttpJson', externalApiMode: !!process.env.USER_CONFIG_API, stdioClient: this.transportType === 'stdio' ? null : undefined, }; // Configure API client with transport info // Convert spaceTools to GradioEndpoints format for backward compatibility const convertSpaceToolsToGradioEndpoints = (spaceTools: SpaceTool[]): GradioEndpoint[] => { return spaceTools.map((spaceTool) => ({ name: spaceTool.name, subdomain: spaceTool.subdomain, id: spaceTool._id, emoji: spaceTool.emoji, })); }; // Use shared default space tools const defaultGradioEndpoints = convertSpaceToolsToGradioEndpoints(DEFAULT_SPACE_TOOLS); let apiClientConfig: ApiClientConfig; // Check for USER_CONFIG_API environment variable const userConfigApi = process.env.USER_CONFIG_API; if (userConfigApi) { // Use external mode with the user config API apiClientConfig = { type: 'external', externalUrl: userConfigApi, hfToken: process.env.DEFAULT_HF_TOKEN, }; logger.info(`Using external API client with user config API: ${userConfigApi}`); } else { // Default to polling mode apiClientConfig = options.apiClientConfig || { type: 'polling', baseUrl: `http://localhost:${String(this.webAppPort)}`, pollInterval: 5000, staticGradioEndpoints: defaultGradioEndpoints, }; logger.info(`Using internal API client with user config API: ${apiClientConfig.baseUrl}}`); } this.apiClient = new McpApiClient(apiClientConfig, transportInfo); // This creates our MCP Server with the standard tools. const originalServerFactory = createServerFactory(this.webServerInstance, this.apiClient); // This adds the Gradio endpoints to the original MCP Server. this.serverFactory = createProxyServerFactory(this.webServerInstance, this.apiClient, originalServerFactory); // Get Express app instance this.appInstance = this.webServerInstance.getApp(); } async start(): Promise<void> { // Set transport info (already created in constructor) const transportInfo = this.apiClient.getTransportInfo(); if (transportInfo) { this.webServerInstance.setTransportInfo(transportInfo); } // Setup tool management for web server this.setupToolManagement(); // Configure API endpoints this.webServerInstance.setupApiRoutes(); // Start web server FIRST await this.startWebServer(); // Initialize transport (before static files to avoid route conflicts) await this.initializeTransport(); // Setup static files (must be AFTER transport routes to avoid catch-all conflicts) await this.webServerInstance.setupStaticFiles(this.isDev); // Start API client (global tool management) await this.startToolManagement(); } private setupToolManagement(): void { // Web server manages tool state directly - no registered tools needed // Initialize tool states and pass API client to WebServer this.webServerInstance.initializeToolStates(); this.webServerInstance.setApiClient(this.apiClient); } private async initializeTransport(): Promise<void> { if (this.transportType === 'unknown') return; try { this.transport = createTransport(this.transportType, this.serverFactory, this.appInstance); // Pass transport to web server for session management this.webServerInstance.setTransport(this.transport); await this.transport.initialize({ port: this.webAppPort, }); } catch (error) { logger.error({ error }, `Error initializing ${this.transportType} transport`); throw error; } } private async startWebServer(): Promise<void> { // WebServer manages its own lifecycle await this.webServerInstance.start(this.webAppPort); logger.info(`Server running at http://localhost:${String(this.webAppPort)}`); logger.info( { transportType: this.transportType, mode: this.isDev ? 'development with HMR' : 'production' }, 'Server configuration' ); if (this.isDev) { logger.info('HMR is active - frontend changes will be automatically reflected in the browser'); logger.info("For server changes, use 'npm run dev:watch' to automatically rebuild and apply changes"); } } private async startToolManagement(): Promise<void> { // Start API client for global tool state management await this.apiClient.startPolling((toolId, enabled) => { logger.debug(`Global tool ${toolId} ${enabled ? 'enabled' : 'disabled'}`); }); } async stop(): Promise<void> { // Stop global API client this.apiClient.stopPolling(); // Signal transport to stop accepting new connections if (this.transport?.shutdown) { this.transport.shutdown(); } logger.info('Shutting down web server...'); await this.webServerInstance.stop(); // Clean up transport if initialized if (this.transport) { await this.transport.cleanup(); } } getExpressApp(): Express { return this.appInstance; } } export function maskToken(token: string): string { if (!token || token.length <= 9) return token; return `${token.substring(0, 4)}...${token.substring(token.length - 5)}`; }