sakenowa-mcp-vercel

Vercel deploy wrapper for @yawaragi/sakenowa-mcp. Exposes the MCP streamable-HTTP endpoint as a Next.js Pages-API function, so the OSS MCP server (which natively wants a long-lived http.Server.listen()) can run on Vercel's serverless model.

The endpoint is at /api/mcp. Point any MCP client (the Vercel AI SDK's @ai-sdk/mcp, Claude Desktop, etc.) at https://<your-deploy>/mcp (with the /api path prefix configured in the wrapper, see below — MCP_HTTP_PATH style env var coming in a follow-up).

How it works

@yawaragi/sakenowa-mcp@0.1.0 ships a streamable-HTTP transport that is already stateless per request — a fresh Server + StreamableHTTPServerTransport is constructed inside every invocation, then closed when the response stream ends. The published createMcpHttpServer(...) wrapper just plugs that per-request handler into Node's http.createServer.

This project does the same thing, but plugs the per-request handler into a Next.js Pages-API function instead. Result: each Vercel function invocation does the equivalent of one stock sakenowa-mcp request, with no state shared between invocations except the pg connection pool (which Vercel keeps warm across requests on the same function container).

The handler lives at pages/api/mcp.ts and mirrors sakenowa-mcp's internal handleRequest (@yawaragi/sakenowa-mcp/dist/http.js) closely.

Deploy

1. Connect this repo to a Vercel project in the Vercel dashboard. Set the project name to sakenowa-mcp (or whatever — the deploy URL is what matters downstream).

2. Set the project region to fra1 (Frankfurt, EU) for DPA continuity with the Supabase mirror. Already pinned in vercel.json.

3. Set the environment variable DATABASE_URL to the Sakenowa-mirrored Postgres connection string. Use the EU pooler URL (aws-1-eu-central-1.pooler.supabase.com:5432), NOT the direct DB URL — serverless concurrency would otherwise blow through max_connections. See .env.example.

4. Deploy. Vercel auto-deploys on push.

5. Smoke-test the deployment:

   curl -s -X POST https://<your-deploy>.vercel.app/api/mcp \
     -H "Content-Type: application/json" \
     -H "Accept: application/json, text/event-stream" \
     -d '{"jsonrpc":"2.0","id":1,"method":"tools/list"}' | jq
   

   Expected: a JSON-RPC response advertising the six tools (list_prefectures, search_sakes_by_name, find_similar_sakes, get_sake_details, find_sakes_by_flavor, get_top_ranked).

6. Point the yawaragi app at the deploy — set MCP_SAKENOWA_URL=https://<your-deploy>.vercel.app/api/mcp on the yawaragi Vercel project (Production + Preview).

Auth

@yawaragi/sakenowa-mcp v0.1.0 ships with no built-in authentication — the OSS asset's contract is "anyone with DATABASE_URL can query, anyone with the HTTP endpoint can query." The data is public-domain Sakenowa data, and no PII / user-state ever passes through the server.

If you want to restrict access, layer auth in front: Vercel rewrite with a bearer token, Cloudflare Tunnel with mTLS, etc. Not built into this wrapper.

Caveats

• enableJsonResponse: true — the wrapper requests plain application/json responses, not the SSE-streamed variant. All six tools are short synchronous reads; streaming would only matter if a future tool added long-running work.
• Cold-start cost: ~200–500ms to construct the pg pool + first MCP Server. Subsequent warm invocations are near-instant.
• Subpath imports (@yawaragi/sakenowa-mcp/dist/server.js): brittle because v0.1.0 has no public exports field. A patch-level follow-up against sakenowa-mcp to add exports mapping is tracked separately; once that ships, switch to named subpath imports here.
• Pool sizing: default Pool has max: 10. Vercel can spawn many parallel function containers; the Supabase pooler handles that fine, but if you switch to a direct DB URL you'd need to tune.

Local dev

pnpm install
DATABASE_URL=postgresql://... pnpm dev   # binds on :3030 by default

# In another terminal
curl -s -X POST http://localhost:3030/api/mcp \
  -H "Content-Type: application/json" \
  -H "Accept: application/json, text/event-stream" \
  -d '{"jsonrpc":"2.0","id":1,"method":"tools/list"}'