Add Streamable HTTP transport for remote MCP access
- Convert from stdio-only to dual-mode (stdio + HTTP) - Add Express server with /mcp endpoint for Streamable HTTP - Add /health endpoint for Railway health checks - Update MCP SDK to v1.12.0 for Streamable HTTP support - Add railway.toml for Railway deployment - Default to HTTP mode, use --stdio flag for local mode
This commit is contained in:
Krishna Kumar
215
src/index.ts
215
src/index.ts
@@ -1,7 +1,12 @@
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#!/usr/bin/env node
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// OpenRouter Multimodal MCP Server
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// Supports both stdio (local) and Streamable HTTP (remote) transports
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import { Server } from '@modelcontextprotocol/sdk/server/index.js';
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import { StdioServerTransport } from '@modelcontextprotocol/sdk/server/stdio.js';
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import { StreamableHTTPServerTransport } from '@modelcontextprotocol/sdk/server/streamableHttp.js';
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import { isInitializeRequest } from '@modelcontextprotocol/sdk/types.js';
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import express, { Request, Response } from 'express';
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import { ToolHandlers } from './tool-handlers.js';
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@@ -15,15 +20,17 @@ interface ServerOptions {
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class OpenRouterMultimodalServer {
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private server: Server;
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private toolHandlers!: ToolHandlers; // Using definite assignment assertion
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private toolHandlers!: ToolHandlers;
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private apiKey: string;
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private defaultModel: string;
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constructor(options?: ServerOptions) {
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// Retrieve API key from options or environment variables
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const apiKey = options?.apiKey || process.env.OPENROUTER_API_KEY;
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const defaultModel = options?.defaultModel || process.env.OPENROUTER_DEFAULT_MODEL || DEFAULT_MODEL;
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this.apiKey = options?.apiKey || process.env.OPENROUTER_API_KEY || '';
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this.defaultModel = options?.defaultModel || process.env.OPENROUTER_DEFAULT_MODEL || DEFAULT_MODEL;
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// Check if API key is provided
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if (!apiKey) {
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if (!this.apiKey) {
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throw new Error('OpenRouter API key is required. Provide it via options or OPENROUTER_API_KEY environment variable');
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}
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@@ -31,7 +38,7 @@ class OpenRouterMultimodalServer {
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this.server = new Server(
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{
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name: 'openrouter-multimodal-server',
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version: '1.0.0',
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version: '1.5.0',
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},
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{
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capabilities: {
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@@ -39,78 +46,204 @@ class OpenRouterMultimodalServer {
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},
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}
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);
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// Set up error handling
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this.server.onerror = (error) => console.error('[MCP Error]', error);
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// Initialize tool handlers
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this.toolHandlers = new ToolHandlers(
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this.server,
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apiKey,
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defaultModel
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this.apiKey,
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this.defaultModel
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);
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process.on('SIGINT', async () => {
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await this.server.close();
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process.exit(0);
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});
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}
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async run() {
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getServer(): Server {
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return this.server;
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}
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getDefaultModel(): string {
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return this.toolHandlers.getDefaultModel() || this.defaultModel;
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}
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async runStdio() {
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const transport = new StdioServerTransport();
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await this.server.connect(transport);
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console.error('OpenRouter Multimodal MCP server running on stdio');
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// Log model information
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const modelDisplay = this.toolHandlers.getDefaultModel() || DEFAULT_MODEL;
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console.error(`Using default model: ${modelDisplay}`);
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console.error(`Using default model: ${this.getDefaultModel()}`);
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console.error('Server is ready to process tool calls. Waiting for input...');
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}
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async runHttp(port: number) {
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const app = express();
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app.use(express.json());
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// Store transports by session ID for stateful mode
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const transports: Record<string, StreamableHTTPServerTransport> = {};
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// Health check endpoint
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app.get('/health', (_req: Request, res: Response) => {
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res.json({
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status: 'ok',
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server: 'openrouter-multimodal-mcp',
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version: '1.5.0',
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defaultModel: this.getDefaultModel()
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});
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});
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// Main MCP endpoint - handles POST and GET
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app.all('/mcp', async (req: Request, res: Response) => {
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console.log(`[MCP] ${req.method} request received`);
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// Handle GET for SSE stream (part of Streamable HTTP spec)
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if (req.method === 'GET') {
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console.log('[MCP] SSE stream requested');
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const sessionId = req.headers['mcp-session-id'] as string | undefined;
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if (!sessionId || !transports[sessionId]) {
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res.status(400).json({ error: 'No active session. Send POST first.' });
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return;
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}
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// Let the transport handle the SSE stream
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const transport = transports[sessionId];
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await transport.handleRequest(req, res);
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return;
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}
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// Handle DELETE for session termination
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if (req.method === 'DELETE') {
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const sessionId = req.headers['mcp-session-id'] as string | undefined;
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if (sessionId && transports[sessionId]) {
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await transports[sessionId].close();
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delete transports[sessionId];
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res.status(200).json({ message: 'Session terminated' });
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} else {
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res.status(404).json({ error: 'Session not found' });
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}
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return;
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}
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// Handle POST requests
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if (req.method !== 'POST') {
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res.status(405).json({ error: 'Method not allowed' });
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return;
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}
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const sessionId = req.headers['mcp-session-id'] as string | undefined;
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let transport: StreamableHTTPServerTransport;
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// Check if this is an initialization request
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if (isInitializeRequest(req.body)) {
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console.log('[MCP] Initialize request - creating new session');
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// Create new transport for stateless mode (no session persistence)
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transport = new StreamableHTTPServerTransport({
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sessionIdGenerator: () => crypto.randomUUID(),
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onsessioninitialized: (newSessionId) => {
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console.log(`[MCP] Session initialized: ${newSessionId}`);
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transports[newSessionId] = transport;
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}
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});
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// Connect a new server instance for this transport
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const sessionServer = new Server(
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{ name: 'openrouter-multimodal-server', version: '1.5.0' },
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{ capabilities: { tools: {} } }
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);
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sessionServer.onerror = (error) => console.error('[MCP Session Error]', error);
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// Initialize tool handlers for this session
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new ToolHandlers(sessionServer, this.apiKey, this.defaultModel);
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await sessionServer.connect(transport);
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} else {
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// Existing session - find transport
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if (!sessionId || !transports[sessionId]) {
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res.status(400).json({
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error: 'Invalid or missing session ID',
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message: 'Send initialize request first to create a session'
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});
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return;
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}
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transport = transports[sessionId];
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}
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// Handle the request
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try {
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await transport.handleRequest(req, res);
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} catch (error) {
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console.error('[MCP] Request handling error:', error);
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if (!res.headersSent) {
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res.status(500).json({ error: 'Internal server error' });
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}
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}
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});
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// Legacy SSE endpoint for backwards compatibility
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app.get('/sse', (_req: Request, res: Response) => {
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res.status(410).json({
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error: 'SSE transport is deprecated',
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message: 'Use Streamable HTTP at /mcp endpoint instead'
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});
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});
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// Start server
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app.listen(port, () => {
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console.log(`OpenRouter Multimodal MCP server running on HTTP port ${port}`);
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console.log(`MCP endpoint: http://localhost:${port}/mcp`);
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console.log(`Health check: http://localhost:${port}/health`);
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console.log(`Using default model: ${this.getDefaultModel()}`);
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});
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}
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}
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// Determine transport mode from environment or arguments
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const transportMode = process.env.MCP_TRANSPORT || 'http';
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const httpPort = parseInt(process.env.PORT || '3001', 10);
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// Get MCP configuration if provided
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let mcpOptions: ServerOptions | undefined;
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// Check if we're being run as an MCP server with configuration
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// Check for config argument
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if (process.argv.length > 2) {
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try {
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const configArg = process.argv.find(arg => arg.startsWith('--config='));
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if (configArg) {
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const configPath = configArg.split('=')[1];
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const configData = require(configPath);
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// Extract configuration
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mcpOptions = {
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apiKey: configData.OPENROUTER_API_KEY || configData.apiKey,
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defaultModel: configData.OPENROUTER_DEFAULT_MODEL || configData.defaultModel
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};
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if (mcpOptions.apiKey) {
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console.error('Using API key from MCP configuration');
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}
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}
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// Check for --stdio flag
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if (process.argv.includes('--stdio')) {
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const server = new OpenRouterMultimodalServer(mcpOptions);
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server.runStdio().catch(console.error);
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} else {
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const server = new OpenRouterMultimodalServer(mcpOptions);
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server.runHttp(httpPort);
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}
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} catch (error) {
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console.error('Error parsing MCP configuration:', error);
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console.error('Error parsing configuration:', error);
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process.exit(1);
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}
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} else {
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// Default: HTTP mode unless MCP_TRANSPORT=stdio
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const server = new OpenRouterMultimodalServer(mcpOptions);
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if (transportMode === 'stdio') {
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server.runStdio().catch(console.error);
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} else {
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server.runHttp(httpPort);
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}
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}
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// Attempt to parse JSON from stdin to check for MCP server parameters
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if (!mcpOptions?.apiKey) {
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process.stdin.setEncoding('utf8');
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process.stdin.once('data', (data) => {
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try {
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const firstMessage = JSON.parse(data.toString());
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if (firstMessage.params && typeof firstMessage.params === 'object') {
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mcpOptions = {
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apiKey: firstMessage.params.OPENROUTER_API_KEY || firstMessage.params.apiKey,
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defaultModel: firstMessage.params.OPENROUTER_DEFAULT_MODEL || firstMessage.params.defaultModel
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};
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}
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} catch (error) {
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// Not a valid JSON message or no parameters, continue with environment variables
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}
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});
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}
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const server = new OpenRouterMultimodalServer(mcpOptions);
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server.run().catch(console.error);
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