Product Architecture

From QR scan to confirmed order in under 30 seconds.

Castille Concierge is a stateless edge web app fronting a thin orchestration layer. Each room's QR encodes its own URL; the guest never types anything. Orders are paid online, then fanned out to the right operator by category — F&B, Adventure, or Taxi — with a parallel notification to the owner.

Core guest flow

1. Scan

Per-room QR encodes /room/{n}

2. Land

Edge-rendered page (<1.5s LCP)

3. Choose

F&B · Adventure · Taxi

4. Pay

Stripe Checkout (3-D Secure)

5. Route

Category → operator

6. Notify

WhatsApp + Email + screen

Notification routing engine

            ┌──────────────┐
            │ Order paid    │
            └──────┬────────┘
                   │
        ┌──────────┴──────────┐
        │ category dispatcher │
        └──┬────────┬─────────┘
           │        │        │
       ╔═══▼══╗  ╔══▼═══╗ ╔══▼═══╗
       ║ F&B  ║  ║ Adv. ║ ║ Taxi ║
       ╚═══╤══╝  ╚══╤═══╝ ╚══╤═══╝
           │        │        │
   WhatsApp ► +356 9900 2201  2202   2203
   Email    ► owner@castille.mt (always)
   In-app   ► role-scoped dashboard

F&B kitchen

+356 9900 2201

Adventure desk

+356 9900 2202

Taxi dispatch

+356 9900 2203

Availability rules

F&B

Order window 10:00 — 04:00. Outside hours: menu browseable, checkout disabled with polite notice.

Adventure

24/7. Subject to weather hold on water activities.

Taxi

24/7. 30-second double-tap block after order placement.

Technology & data

Edge runtime

Cloudflare Workers, sub-30ms cold start, deployed to EU-South-1.

Orchestration

TanStack Start server fns; idempotent webhook handlers.

Data

Postgres + RLS. Orders, rooms, menu, audit log.

Payments

Stripe Checkout (Malta-compatible, SCA-ready).

Meta Cloud API templates; per-category number routing.

Postmark transactional with retries + DKIM/SPF.

Security

TLS 1.3, signed webhooks, scoped session cookies.

Performance

P95 page load 1.2s on hotel Wi-Fi; image LQIP.

Order state machine

  draft ─► pending ─► preparing ─► out_for_delivery ─► completed
              │             │                │
              └────► cancelled ◄─────────────┘   (refund issued via Stripe)

draft

pending

preparing

out for delivery

completed