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| 1 | +import express from 'express'; |
| 2 | +import type { Request, Response } from 'express'; |
| 3 | +import cors from 'cors'; |
| 4 | +import type { SessionManager } from './session-manager'; |
| 5 | + |
| 6 | +export function setupMCPRoutes( |
| 7 | + sessionManager: SessionManager |
| 8 | +): express.Application { |
| 9 | + const app = express(); |
| 10 | + |
| 11 | + app.use( |
| 12 | + cors({ |
| 13 | + origin: '*', // use "*" with caution in production |
| 14 | + methods: 'GET,POST,DELETE', |
| 15 | + preflightContinue: false, |
| 16 | + optionsSuccessStatus: 204, |
| 17 | + exposedHeaders: [ |
| 18 | + 'mcp-session-id', |
| 19 | + 'last-event-id', |
| 20 | + 'mcp-protocol-version', |
| 21 | + ], |
| 22 | + }) |
| 23 | + ); // Enable CORS for all routes so Inspector can connect |
| 24 | + |
| 25 | + // Handle MCP POST requests (initialization and regular requests) |
| 26 | + app.post('/mcp', async (req: Request, res: Response) => { |
| 27 | + console.error('Received MCP POST request'); |
| 28 | + try { |
| 29 | + // Check for existing session ID |
| 30 | + const sessionId = req.headers['mcp-session-id'] as string | undefined; |
| 31 | + |
| 32 | + if (sessionId && sessionManager.hasSession(sessionId)) { |
| 33 | + // Reuse existing session |
| 34 | + const session = sessionManager.getSession(sessionId)!; |
| 35 | + await session.transport.handleRequest(req, res); |
| 36 | + return; |
| 37 | + } else if (!sessionId) { |
| 38 | + // New initialization request |
| 39 | + await sessionManager.createSession(req, res); |
| 40 | + return; |
| 41 | + } else { |
| 42 | + // Invalid request - session ID provided but not found |
| 43 | + res.status(400).json({ |
| 44 | + jsonrpc: '2.0', |
| 45 | + error: { |
| 46 | + code: -32000, |
| 47 | + message: 'Bad Request: Session not found or invalid', |
| 48 | + }, |
| 49 | + id: (req.body as { id?: string })?.id, |
| 50 | + }); |
| 51 | + return; |
| 52 | + } |
| 53 | + } catch (error) { |
| 54 | + console.error('Error handling MCP request:', error); |
| 55 | + if (!res.headersSent) { |
| 56 | + res.status(500).json({ |
| 57 | + jsonrpc: '2.0', |
| 58 | + error: { |
| 59 | + code: -32603, |
| 60 | + message: 'Internal server error', |
| 61 | + }, |
| 62 | + id: (req.body as { id?: string })?.id, |
| 63 | + }); |
| 64 | + } |
| 65 | + } |
| 66 | + }); |
| 67 | + |
| 68 | + // Handle GET requests for SSE streams (using built-in support from StreamableHTTP) |
| 69 | + app.get('/mcp', async (req: Request, res: Response) => { |
| 70 | + console.error('Received MCP GET request'); |
| 71 | + const sessionId = req.headers['mcp-session-id'] as string | undefined; |
| 72 | + if (!sessionId || !sessionManager.hasSession(sessionId)) { |
| 73 | + res.status(400).json({ |
| 74 | + jsonrpc: '2.0', |
| 75 | + error: { |
| 76 | + code: -32000, |
| 77 | + message: 'Bad Request: No valid session ID provided', |
| 78 | + }, |
| 79 | + id: (req.body as { id?: string })?.id, |
| 80 | + }); |
| 81 | + return; |
| 82 | + } |
| 83 | + |
| 84 | + // Check for Last-Event-ID header for resumability |
| 85 | + const lastEventId = req.headers['last-event-id'] as string | undefined; |
| 86 | + if (lastEventId) { |
| 87 | + console.error(`Client reconnecting with Last-Event-ID: ${lastEventId}`); |
| 88 | + } else { |
| 89 | + console.error(`Establishing new SSE stream for session ${sessionId}`); |
| 90 | + } |
| 91 | + |
| 92 | + const session = sessionManager.getSession(sessionId)!; |
| 93 | + await session.transport.handleRequest(req, res); |
| 94 | + }); |
| 95 | + |
| 96 | + // Handle DELETE requests for session termination (according to MCP spec) |
| 97 | + app.delete('/mcp', async (req: Request, res: Response) => { |
| 98 | + const sessionId = req.headers['mcp-session-id'] as string | undefined; |
| 99 | + if (!sessionId || !sessionManager.hasSession(sessionId)) { |
| 100 | + res.status(400).json({ |
| 101 | + jsonrpc: '2.0', |
| 102 | + error: { |
| 103 | + code: -32000, |
| 104 | + message: 'Bad Request: No valid session ID provided', |
| 105 | + }, |
| 106 | + id: (req.body as { id?: string })?.id, |
| 107 | + }); |
| 108 | + return; |
| 109 | + } |
| 110 | + |
| 111 | + console.error( |
| 112 | + `Received session termination request for session ${sessionId}` |
| 113 | + ); |
| 114 | + |
| 115 | + try { |
| 116 | + const session = sessionManager.getSession(sessionId); |
| 117 | + if (session) { |
| 118 | + await session.transport.handleRequest(req, res); |
| 119 | + } |
| 120 | + } catch (error) { |
| 121 | + console.error('Error handling session termination:', error); |
| 122 | + if (!res.headersSent) { |
| 123 | + res.status(500).json({ |
| 124 | + jsonrpc: '2.0', |
| 125 | + error: { |
| 126 | + code: -32603, |
| 127 | + message: 'Error handling session termination', |
| 128 | + }, |
| 129 | + id: (req.body as { id?: string })?.id, |
| 130 | + }); |
| 131 | + return; |
| 132 | + } |
| 133 | + } |
| 134 | + }); |
| 135 | + |
| 136 | + return app; |
| 137 | +} |
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