mcp.cashu.exchange

Agents that pay for the real world

Berlin · 2026 · Amperstrand

The gap

• Agents can find services — search, maps, MCP servers everywhere
• They cannot pay: commerce ends at a checkout page built for humans
• Wiring in a card means card numbers in code, secrets, and logs
• Bitcoin rails exist — but nothing connects them to real merchants

We connected them. Safely.

The idea

One exchange, three pieces:

• Registry of payable services — food, charging, cinema, parking
• Gateway to federated private kits (their data never goes public)
• Swappable payment rails — Cashu, own-card checkout handoff, Lightning (stretch)

One capability, many surfaces: MCP tool, REST, library, CLI.
The client decides how to talk to us.

Architecture

 participant ──► worker (Cloudflare)
   own inbox (cashu.email npub)      POST /mcp · /api/search · chat
   own card (2fiat or personal)        │
        │                              ▼
        │              registry ── charging · cinema · jamezz food
        │              gateway ──► private kits (europark parking)
        │              rails ──── own-card handoff (holds no card)
        ▼
   Numo POS ── customer pays Bitcoin (Cashu tap / Lightning)
        │
        ▼
   numo-bridge ──► jamezz client ──► venue API ──► Mollie checkout
                                              (operator completes, own card)

Full diagram: README · Verified surfaces: docs/LIVE.md

Real venue, real menu

• Jamezz: 2,000+ venues, 25+ countries — Germany is a main market
• One photographed table QR → full menu in one command
  (npx jamezz menu 8613S3X — live, EUR prices)
• Worked example: Burgermeister Mehringdamm, Berlin
• 21 offline tests against synthetic transports — no captured data
• The onboarding method is a deliverable: prompts/ in the jamezz repo

The customer pays Bitcoin

Numo (cashubtc) — Android POS:

• Cashu ecash tap-2-pay (NFC) and Lightning invoices
• Catalog loaded from our API — the real menu, real prices
• Customer-side rail needs no account, no card, no KYC

Proven 2026-10-02: two live webhook payments (Cashu + Lightning)
drove the full loop — the venue accepted the order and the hosted
checkout answered.

The venue gets paid its way

1. Paid basket → numo-bridge → jamezz prepare()+submit()
2. Venue creates the order → Mollie hosted checkout URL
3. The operator completes it with their own card
4. payDirect=1: the kitchen fires only when the venue is paid

Customer paid Bitcoin. Venue got paid normally.
No card number entered any system of ours.

The boundary (why this is open-source-safe)

• No PAN, CVC, or card automation in any repo, secret, or tool response
  — the card-details tool was deleted, not gated
• Leak gates in CI: tree + full git history, both repos, every push
• Commit-time blockers for HAR/log/env files
• Access audit: 12 collaborators removed, 7 invites revoked (private kits)
• Payment boundary = a hosted checkout URL + a human hand

Live now (verified 2026-10-02)

• mcp.cashu.exchange — health OK, 5 MCP tools, stateless streamable HTTP
• Cinema chat settled in Cashu (Testnut mint)
• Berlin EV map (OSM/Overpass, KV-cached)
• Federated parking (europark-mcp) answering through the gateway
• Weekly smoke: live venue check, green

Everything merged goes public the moment the deploy token is set.

48 hours

• Day 0: one private kit, captured data, cards in fixtures
• Day 1: extraction → two leak-gated public repos; card-free refactor;
  collaborator + card audit; architecture + live docs
• Day 2: typed client, offline test suites, CLI, generic REST surface,
  plugin-jamezz — the POS loop proven end to end — and a 75-venue
  catalog plus two more platform clients (gastronovi, ordermonkey) via the recon pipeline
  (live payments → real venue order → hosted checkout)
• Platform drift found in the wild (jamezz-v2.0) → filed → fixed upstream
  same day, with tests

Roadmap

• Now: deploy token → live jamezz.search + /api/search
• Hours: Numo catalog on hardware phone, bridge order test (free pipeline)
• Next: more tables (a lunch trip = +1 venue), pecan numeraires,
  npm publish decision
• Vision: any QR-ordering venue on Earth, payable in Bitcoin,
  safely open-sourceable

Try it

docs/TOUR.md — zero to a paid burger in one afternoon:

1. Call the live exchange (5 min)
2. Order real food with your own card (30 min)
3. Run the exchange yourself (10 min)
4. Extend it — prompts do the onboarding

github.com/Amperstrand/mcp-cashu-exchange
github.com/Amperstrand/jamezz

One prompt and a QR code away from a paid burger.