No run ${req.params.id}

`);\n return;\n }\n res.type('html').send(renderResults(run.scenarioName, run.id, checks));\n });\n\n app.get('/results/:id', (req, res) => {\n const run = sessions.get(req.params.id);\n const checks = sessions.results(req.params.id);\n if (!run || !checks) {\n res.status(404).json({ error: 'unknown run' });\n return;\n }\n res.json(summarise(run.scenarioName, run.id, checks));\n });\n\n app.delete('/results/:id', async (req, res) => {\n await sessions.destroy(req.params.id);\n res.status(204).end();\n });\n\n // ---------- meta MCP server ----------\n\n app.post('/mcp', express.json(), async (req, res) => {\n const server = createMetaMcpServer(sessions, origin(req), (s, id) =>\n runBaseUrl(req, s, id)\n );\n const transport = new StreamableHTTPServerTransport({\n sessionIdGenerator: undefined\n });\n await server.connect(transport);\n await transport.handleRequest(req, res, req.body);\n res.on('close', () => {\n transport.close();\n server.close();\n });\n });\n\n return { app, sessions };\n}\n\nfunction summarise(scenario: string, id: string, checks: ConformanceCheck[]) {\n const counts = { SUCCESS: 0, FAILURE: 0, WARNING: 0, SKIPPED: 0, INFO: 0 };\n for (const c of checks) counts[c.status]++;\n return {\n runId: id,\n scenario,\n summary: {\n passed: counts.SUCCESS,\n failed: counts.FAILURE,\n warnings: counts.WARNING,\n info: counts.INFO,\n skipped: counts.SKIPPED,\n total: checks.length\n },\n checks\n };\n}\n\nfunction createMetaMcpServer(\n sessions: SessionManager,\n publicOrigin: string,\n runBaseUrl: (scenario: string, runId: string) => string\n): Server {\n const server = new Server(\n { name: 'mcp-conformance-hosted', version: '0.2.0' },\n { capabilities: { tools: {} } }\n );\n\n server.setRequestHandler(ListToolsRequestSchema, async () => ({\n tools: [\n {\n name: 'list_scenarios',\n description:\n 'List client-conformance scenarios this hosted instance can serve.',\n inputSchema: { type: 'object', properties: {} }\n },\n {\n name: 'start_run',\n description:\n 'Create a fresh run for a scenario and return the MCP URL to point ' +\n 'the client-under-test at, plus the results URL. The run-id is ' +\n 'embedded in the path so this works with stateless transports.',\n inputSchema: {\n type: 'object',\n properties: {\n scenario: {\n type: 'string',\n description: 'Scenario name, e.g. \"initialize\" or \"tools_call\".'\n },\n run_id: {\n type: 'string',\n description:\n 'Optional. Supply your own [A-Za-z0-9_-]{1,64} id; ' +\n 'otherwise one is generated.'\n }\n },\n required: ['scenario']\n }\n },\n {\n name: 'get_results',\n description:\n 'Fetch the conformance checks recorded for a run. Same shape as ' +\n 'GET /results/.',\n inputSchema: {\n type: 'object',\n properties: { run_id: { type: 'string' } },\n required: ['run_id']\n }\n }\n ]\n }));\n\n server.setRequestHandler(\n CallToolRequestSchema,\n async (request): Promise => {\n const args = (request.params.arguments ?? {}) as Record;\n switch (request.params.name) {\n case 'list_scenarios':\n return text(\n JSON.stringify(\n listHostableScenarios().map((name) => ({\n name,\n description: getScenario(name)!.description\n })),\n null,\n 2\n )\n );\n\n case 'start_run': {\n if (args.run_id && !RUN_ID_RE.test(args.run_id)) {\n return errorText(`invalid run_id (must match ${RUN_ID_RE})`);\n }\n try {\n const run = sessions.getOrCreate(args.scenario, args.run_id, (id) =>\n runBaseUrl(args.scenario, id)\n );\n return text(\n JSON.stringify(\n {\n runId: run.id,\n mcpUrl: `${runBaseUrl(run.scenarioName, run.id)}${run.mcpPath}`,\n resultsUrl: `${publicOrigin}/results/${run.id}`,\n resultsHtmlUrl: `${publicOrigin}/results/${run.id}.html`,\n context: run.context\n },\n null,\n 2\n )\n );\n } catch (e) {\n if (\n e instanceof UnknownScenarioError ||\n e instanceof NotHostableError\n ) {\n return errorText(e.message);\n }\n throw e;\n }\n }\n\n case 'get_results': {\n const run = sessions.get(args.run_id);\n const checks = sessions.results(args.run_id);\n if (!run || !checks) return errorText(`no run '${args.run_id}'`);\n return text(\n JSON.stringify(summarise(run.scenarioName, run.id, checks), null, 2)\n );\n }\n\n default:\n return errorText(`unknown tool ${request.params.name}`);\n }\n }\n );\n\n return server;\n}\n\nfunction text(t: string): CallToolResult {\n return { content: [{ type: 'text', text: t }] };\n}\n\nfunction errorText(t: string): CallToolResult {\n return { content: [{ type: 'text', text: t }], isError: true };\n}\n",[],[133,648,650],"b7cc5b0e-5b64-11f1-9ce4-ee650bb23af1","html.ts","b7cc5bcc-5b64-11f1-9ce4-ee650bb23af1",5,["D",1780062356323],"import { ConformanceCheck, CheckStatus } from '../types.ts';\n\nconst STATUS_STYLE: Record = {\n SUCCESS: 'background:#d1fae5;color:#065f46',\n FAILURE: 'background:#fee2e2;color:#991b1b',\n WARNING: 'background:#fef3c7;color:#92400e',\n SKIPPED: 'background:#e5e7eb;color:#374151',\n INFO: 'background:#dbeafe;color:#1e40af'\n};\n\nconst css = `\n body{font:14px/1.5 ui-sans-serif,system-ui,sans-serif;max-width:960px;\n margin:2rem auto;padding:0 1rem;color:#111}\n code,pre{font:12px/1.4 ui-monospace,SFMono-Regular,Menlo,monospace}\n pre{background:#f6f8fa;padding:.75rem;border-radius:6px;overflow:auto}\n .pill{display:inline-block;padding:2px 8px;border-radius:10px;\n font-size:11px;font-weight:600}\n .check{border:1px solid #e5e7eb;border-radius:6px;padding:.75rem;\n margin:.5rem 0}\n .check h3{margin:0 0 .25rem;font-size:14px}\n details>summary{cursor:pointer;color:#6b7280;font-size:12px}\n table{border-collapse:collapse;width:100%}\n td,th{text-align:left;padding:.4rem .6rem;border-bottom:1px solid #eee}\n a{color:#2563eb}\n`;\n\nfunction esc(s: string): string {\n return s.replace(\n /[&<>\"]/g,\n (c) => ({ '&': '&', '<': '<', '>': '>', '\"': '"' })[c]!\n );\n}\n\nexport function renderLanding(origin: string, scenarios: string[]): string {\n const rows = scenarios\n .map(\n (n) =>\n `${esc(n)}` +\n `${esc(origin)}/s/${esc(n)}/<run-id>` +\n `mint`\n )\n .join('');\n return `\nMCP Conformance — hosted\n

MCP Conformance — hosted

Point your MCP client at /s/<scenario>/<run-id>.\nPick any <run-id> (e.g. local-1) — the run is\ncreated on first request, and because the id is in the path it works with\nstateless transports too. Then GET\n/results/<run-id> (append .html for a\nreport).

Too lazy to pick an id? GET /s/<scenario> mints one and\nreturns {mcpUrl, resultsUrl}.

This server is also an MCP server at ${esc(origin)}/mcp with\nlist_scenarios / start_run /\nget_results tools.

Scenarios (${scenarios.length})

\n${rows}

name	MCP URL pattern

Example

$ npx @modelcontextprotocol/inspector ${esc(origin)}/s/initialize/demo\n$ curl ${esc(origin)}/results/demo | jq .summary

`;\n}\n\nexport function renderResults(\n scenario: string,\n sessionId: string,\n checks: ConformanceCheck[]\n): string {\n const items = checks\n .map((c) => {\n const pill = `${c.status}`;\n const refs = (c.specReferences ?? [])\n .map((r) =>\n r.url\n ? `${esc(r.id)}`\n : `${esc(r.id)}`\n )\n .join(' · ');\n const details =\n c.details || c.errorMessage\n ? `

details

${esc(\n              JSON.stringify(\n                { errorMessage: c.errorMessage, ...c.details },\n                null,\n                2\n              )\n            )}

`\n : '';\n return `

${pill} `${esc(c.id)}` — ${esc(\n c.name\n )}

${esc(c.description)}

${refs}

${details}

`;\n })\n .join('');\n const passed = checks.filter((c) => c.status === 'SUCCESS').length;\n const failed = checks.filter((c) => c.status === 'FAILURE').length;\n return `\n${esc(scenario)} — ${sessionId}\n

`${esc(scenario)}`

session ${esc(sessionId)} — ${passed} passed, ${failed} failed,\n${checks.length} total

${items}`;\n}\n",[],[133,648,657],"b70c7fc8-5b64-11f1-8713-ee650bb23af1",["D",1780062355087],[165,166,167],[133,648],"c30829c6-5b64-11f1-be20-ee650bb23af1",["D",1780062375192],[],[133,46,33],"c3084fa0-5b64-11f1-be20-ee650bb23af1",["D",1780062375192],[163],[133,46],["D",1780062355087],[162,164,168,221],[133],"b6ab618e-5b64-11f1-bb92-ee650bb23af1","valtown.ts","b6ab6260-5b64-11f1-bb92-ee650bb23af1","cc09b591-ab36-47d7-a7a0-618641fcafb7",["D",1780062354427],"/**\n * MCP conformance — val.town deployment.\n *\n * The hosted runner mounts each scenario's `handler()` (a Node\n * `RequestListener`) under `/s//`. On val.town the entry\n * point is a fetch handler, so we bridge web Request→Node req/res once and\n * reuse the *real* scenario implementations from the package — no\n * reimplementation, no loopback port.\n *\n * Deploy: create an HTTP val and paste:\n *\n * import handler from \"https://esm.sh/@modelcontextprotocol/conformance/examples/hosted/valtown.ts\";\n * export default handler;\n *\n * or copy this file in directly. Requires a runtime with Node-compat\n * (`node:http`, `node:stream`) — val.town, Deno Deploy, Bun all qualify.\n *\n * Limitation: scenarios that rely on long-lived SSE streams or connection-\n * close timing (`sse-retry`) won't behave correctly through a buffered\n * Request→Response bridge. They're filtered out below.\n */\n\nimport { IncomingMessage, ServerResponse } from 'node:http';\nimport { Socket } from 'node:net';\nimport { createHostedApp } from '../../src/hosted/server.ts';\n\nconst NOT_FETCH_SAFE = new Set(['sse-retry']);\n\n// Auth scenarios need a second public origin (RFC 8414 well-known is\n// origin-rooted). Deploy examples/hosted/valtown-relay.ts as a separate val\n// and point CONFORMANCE_AS_ORIGIN at it; both vals share\n// CONFORMANCE_RELAY_SECRET so /__aux can't be hit directly.\nconst { app } = createHostedApp({\n auxOrigins: {\n as: process.env.CONFORMANCE_AS_ORIGIN,\n as2: process.env.CONFORMANCE_AS2_ORIGIN,\n idp: process.env.CONFORMANCE_IDP_ORIGIN\n },\n relaySecret: process.env.CONFORMANCE_RELAY_SECRET\n});\n\nexport default async function (request: Request): Promise {\n const url = new URL(request.url);\n\n // Short-circuit scenarios that need true streaming.\n const m = url.pathname.match(/^\\/s\\/([^/]+)/);\n if (m && NOT_FETCH_SAFE.has(m[1])) {\n return Response.json(\n {\n error: `scenario '${m[1]}' relies on SSE stream lifecycle and is not available via the fetch bridge`\n },\n { status: 501 }\n );\n }\n\n // --- web Request → Node IncomingMessage ---\n const body = request.body\n ? Buffer.from(await request.arrayBuffer())\n : undefined;\n // Express's req.protocol/req.ip read socket.encrypted/.remoteAddress, and\n // IncomingMessage._destroy calls socket.destroy(), so a real (unconnected)\n // Socket with the encrypted flag patched on is the path of least surprise.\n const socket = Object.assign(new Socket(), { encrypted: false });\n const nodeReq = new IncomingMessage(socket);\n nodeReq.method = request.method;\n nodeReq.url = url.pathname + url.search;\n nodeReq.httpVersion = '1.1';\n nodeReq.httpVersionMajor = 1;\n nodeReq.httpVersionMinor = 1;\n nodeReq.headers = Object.fromEntries(request.headers);\n nodeReq.headers.host ??= url.host;\n if (body?.length) nodeReq.headers['content-length'] = String(body.length);\n // The SDK's StreamableHTTPServerTransport converts Node→Web via\n // @hono/node-server, which reads rawHeaders (the [k,v,k,v,...] array),\n // not the parsed headers object. Deno's node:http compat exposes\n // rawHeaders as a getter-only accessor, so shadow it with an own\n // property instead of assigning.\n Object.defineProperty(nodeReq, 'rawHeaders', {\n value: Object.entries(nodeReq.headers).flat() as string[],\n writable: true,\n configurable: true\n });\n if (body?.length) nodeReq.push(body);\n nodeReq.push(null);\n\n // --- Node ServerResponse → web Response ---\n // Intercept the user-facing write surface (writeHead/setHeader/write/end)\n // so we never touch ServerResponse's socket-coupled internals. This is the\n // approach serverless-http and light-my-request take.\n const nodeRes = new ServerResponse(nodeReq);\n const chunks: Buffer[] = [];\n let status = 200;\n const headers = new Headers();\n\n const captureHeaders = (h?: Record) => {\n for (const [k, v] of Object.entries(h ?? {})) {\n headers.set(k, Array.isArray(v) ? v.join(', ') : String(v));\n }\n };\n nodeRes.setHeader = ((k: string, v: string | string[] | number) => {\n headers.set(k, Array.isArray(v) ? v.join(', ') : String(v));\n return nodeRes;\n }) as ServerResponse['setHeader'];\n nodeRes.getHeader = (k: string) => headers.get(k.toLowerCase()) ?? undefined;\n nodeRes.removeHeader = (k: string) => headers.delete(k);\n nodeRes.writeHead = ((code: number, h?: Record) => {\n status = code;\n captureHeaders(h);\n return nodeRes;\n }) as ServerResponse['writeHead'];\n nodeRes.write = ((c: string | Buffer, enc?: BufferEncoding) => {\n if (c) chunks.push(typeof c === 'string' ? Buffer.from(c, enc) : c);\n return true;\n }) as ServerResponse['write'];\n nodeRes.flushHeaders = () => {};\n Object.defineProperty(nodeRes, 'statusCode', {\n get: () => status,\n set: (v: number) => {\n status = v;\n }\n });\n\n return new Promise((resolve) => {\n nodeRes.end = ((c?: string | Buffer, enc?: BufferEncoding) => {\n if (c) chunks.push(typeof c === 'string' ? Buffer.from(c, enc) : c);\n resolve(\n new Response(chunks.length ? Buffer.concat(chunks) : null, {\n status,\n headers\n })\n );\n return nodeRes;\n }) as ServerResponse['end'];\n\n app(nodeReq, nodeRes);\n });\n}\n",[],[143,648,680],"b6abc1a6-5b64-11f1-bb92-ee650bb23af1",["D",1780062354427],[160],[143,648],["D",1780062354427],[159],[143],["D",1780062353614],{"_100":99,"_107":103},{"_100":99,"_101":-5,"_102":103,"_18":60,"_104":105,"_106":25},{"_13":89,"_32":90,"_49":42,"_91":50,"_92":-5,"_93":-5,"_94":-5,"_95":-5,"_96":-5,"_97":51,"_98":99},"ctx",{"_82":-5,"_127":731,"_732":733,"_734":735,"_736":25,"_737":25,"_738":25,"_739":138,"_740":-5,"_741":-7,"_742":-7,"_743":66,"_744":25,"_745":25,"_746":-5,"_747":25,"_748":25,"_749":25,"_750":-5},"ENV",{"_702":703,"_704":705,"_706":90,"_707":708,"_709":710,"_711":712,"_713":714,"_715":716,"_717":718,"_719":720,"_721":722,"_723":724,"_725":726,"_727":728,"_729":730},"REACT_APP_SENTRY_DSN","https://586020d86f05489db63a554690acf1e9@o1398359.ingest.sentry.io/6724499","RENDER_GIT_COMMIT","e87eb04e707cf64e7e532c8e8ec395f209e17f15","RENDER_GIT_BRANCH","POSTHOG_API_TOKEN","phc_nmoyuAkStEZuUp69rYlg1DZgrIt19Gx0Y4Hwf8tGgJP","POSTHOG_API_HOST","https://wart.val.town","WEB_API_TEMPLATE","https://{val}.web.val.run","APP_URL","https://www.val.town","MODULE_URL","https://esm.town","VANITY_WEB_API_TEMPLATE","https://{label}.val.run/","DENOLS_URL","https://lsp.val.town","NODE_ENV","production","CLOUDFLARE_TURNSTILE_SITE_KEY","0x4AAAAAACtaIZJH7s9rBMZ6","GOOGLE_CLIENT_ID","875989696899-jtsqkhlbdv5jrlsk8631p7ipjg3c6o62.apps.googleusercontent.com","STRIPE_PUBLISHABLE_KEY","pk_live_51N2zvWEpZTTLipIkVEwXrUG9AT0yeOOEYxszarZT1jpsZV58Ly6wlg3SltZpHN26CUalOBmUSY7adQRQiSkCZz2500qSXNkf8Y","API_URL","https://api.val.town",[],"preferencesKeybindings","default","preferencesTheme","light","preferencesFixers","preferencesCopilot","preferencesSelectionAi","preferencesCloseBrackets","preferencesChatPanelState","preferencesDprint","preferencesDenofmt","notificationCount","flagDenols","isBusinessOrgMember","businessOrgHandle","isBusinessOrgAdmin","isHigherTownieTier","navCollapsed","currentOrgId"]

MCP Conformance — hosted

Scenarios (${scenarios.length})

Example

${pill} ${esc(c.id)} — ${esc(\n c.name\n )}

${esc(scenario)}

${pill} `${esc(c.id)}` — ${esc(\n c.name\n )}

`${esc(scenario)}`

Diff · v53