mcpctl/src/mcplocal/tests/mcp-endpoint-wire-names.test.ts

import { describe, it, expect, vi } from 'vitest';
import Fastify from 'fastify';
import { registerMcpEndpoint } from '../src/http/mcp-endpoint.js';
import type { McpRouter } from '../src/router.js';
import type { JsonRpcRequest, JsonRpcResponse } from '../src/types.js';

/**
 * End-to-end over the Streamable HTTP transport: the /mcp endpoint must serve
 * OpenAI-safe tool names on tools/list and map them back to the router's
 * canonical `server/tool` names on tools/call (the librechat fetch_content
 * incident, 2026-08-25).
 */

function parseSse(body: string): JsonRpcResponse {
  const dataLine = body.split('\n').find((l) => l.startsWith('data: '));
  if (!dataLine) throw new Error(`no SSE data line in: ${body}`);
  return JSON.parse(dataLine.slice('data: '.length)) as JsonRpcResponse;
}

describe('registerMcpEndpoint wire names', () => {
  it('lists wire-safe names and routes calls back to canonical names', async () => {
    const routed: JsonRpcRequest[] = [];
    const fakeRouter = {
      route: vi.fn(async (req: JsonRpcRequest): Promise<JsonRpcResponse> => {
        routed.push(req);
        switch (req.method) {
          case 'initialize':
            return {
              jsonrpc: '2.0',
              id: req.id,
              result: {
                protocolVersion: '2024-11-05',
                serverInfo: { name: 'test', version: '0' },
                capabilities: { tools: {} },
              },
            };
          case 'tools/list':
            return {
              jsonrpc: '2.0',
              id: req.id,
              result: { tools: [{ name: 'websearch/fetch_content', inputSchema: { type: 'object' } }] },
            };
          case 'tools/call':
            return {
              jsonrpc: '2.0',
              id: req.id,
              result: { content: [{ type: 'text', text: 'ok' }] },
            };
          default:
            return { jsonrpc: '2.0', id: req.id, result: {} };
        }
      }),
    } as unknown as McpRouter;

    const app = Fastify();
    registerMcpEndpoint(app, fakeRouter);
    await app.ready();
    try {
      const headers = {
        'content-type': 'application/json',
        accept: 'application/json, text/event-stream',
      };

      const init = await app.inject({
        method: 'POST',
        url: '/mcp',
        headers,
        payload: { jsonrpc: '2.0', id: 1, method: 'initialize', params: { protocolVersion: '2024-11-05', capabilities: {}, clientInfo: { name: 't', version: '0' } } },
      });
      expect(init.statusCode).toBe(200);
      const sessionId = init.headers['mcp-session-id'] as string;
      expect(sessionId).toBeTruthy();
      const sessionHeaders = { ...headers, 'mcp-session-id': sessionId };

      const list = await app.inject({
        method: 'POST',
        url: '/mcp',
        headers: sessionHeaders,
        payload: { jsonrpc: '2.0', id: 2, method: 'tools/list' },
      });
      const listResponse = parseSse(list.body);
      const tools = (listResponse.result as { tools: Array<{ name: string }> }).tools;
      expect(tools.map((t) => t.name)).toEqual(['websearch_fetch_content']);

      const call = await app.inject({
        method: 'POST',
        url: '/mcp',
        headers: sessionHeaders,
        payload: { jsonrpc: '2.0', id: 3, method: 'tools/call', params: { name: 'websearch_fetch_content', arguments: { url: 'https://x' } } },
      });
      const callResponse = parseSse(call.body);
      expect(callResponse.error).toBeUndefined();

      const routedCall = routed.find((r) => r.method === 'tools/call');
      expect(routedCall?.params?.['name']).toBe('websearch/fetch_content');
    } finally {
      await app.close();
    }
  });
});