Product Requirements Document (PRD)

System Architecture & Technical Specifications for Raku's Kitchen Ordering Engine

1. System Overview & Technical Architecture

The Raku's Kitchen Platform is built as a server-rendered, edge-optimized progressive web application using Next.js 14 App Router, backed by Google Cloud Firestore for real-time order state distribution and Firebase Authentication for frictionless phone OTP verification.

2. Detailed Functional Specifications

Module 1: Catalog & Weight-Based Biryani Engine

• Weight Selection Model: Biryani can be ordered in ½ kg, 1 kg, 2 kg, and 3 kg weight tiers. Non-biryani gravies (Chilly Chicken, Mutton Chops) are selectable in ½ kg and 1 kg weight portions.
• Extra Meat Add-on Rules: Customers can add extra meat (in 250g increments) up to a strict cap determined by the base container weight.
• Composite Cart Keying: Cart lines are stored under composite keys (menuId, variant). Orphan extra-meat lines are automatically purged or clamped if parent lines are decremented.
• Packaging Calculation: Fixed packaging fee of ₹20 per individual item unit is computed automatically.

Module 2: Cart & Server-Side Price Verification

Module 3: Slot Scheduling & Operational Constraints

• Meal Slot Picker: Customers select between Lunch (ready at 12:30 PM) and Dinner (ready at 7:30 PM).
• Date Validation: Mondays and Thursdays are blocked. Sunday dinner slots are blocked. 1-day advance booking rules are enforced at the API boundary.

Module 4: Address Verification & Geolocation

• Ola Maps Autocomplete: Real-time address typeahead restricted to Bangalore geofence.
• Structured Address Schema: Captures complete flat/door number, landmark, pin code, street address, and exact lat/lng coordinates to power courier dispatch.

Module 5: Payment Processing (Razorpay)

• Server-Side Order Creation: Next.js Route Handler calls razorpay.orders.create with strictly verified rupee amounts.
• Webhook Verification: Cryptographic HMAC SHA256 signature verification validates razorpay_signature before moving order status to Confirmed.

Module 6: Kitchen Admin Operations Dashboard (`/admin`)

• Real-Time Firestore Feed: Orders render instantaneously without page refreshes via Firestore listeners.
• Priority Status Workflow: Orders navigate through a strict state machine: Confirmed → Preparing → Out for Delivery → Delivered (or Cancelled).
• Logistics 1-Click Booking:
  • Borzo Business API: Calculates delivery quotes and books two-wheeler couriers with pickup instructions in 1 click.
  • Porter Integration: Generates formatted delivery notes and launches Porter app deep-links with customer address on the clipboard.
• Customer WhatsApp Sync: Dedicated click-to-chat links prefill localized status updates with order numbers, ETA, and tracking info.

3. Cloud Firestore Data Schema

Canonical JSON structure for the orders collection:

{
  "orderId": "RK-2026-1004-9842",
  "customer": {
    "name": "Arun Kumar",
    "phone": "+919876543210",
    "uid": "fb_auth_user_9921"
  },
  "slot": {
    "date": "2026-10-05",
    "meal": "lunch",
    "readyTime": "12:30 PM"
  },
  "items": [
    {
      "id": "chicken-biryani",
      "variant": "1kg",
      "quantity": 2,
      "unitPrice": 799,
      "extraMeat": 250,
      "extraMeatCost": 150
    }
  ],
  "financials": {
    "subtotal": 1898,
    "packagingFee": 40,
    "deliveryFee": 0, // Paid to courier directly
    "total": 1938
  },
  "payment": {
    "provider": "razorpay",
    "orderId": "order_PUh298hsdf",
    "paymentId": "pay_PUh3872hf",
    "status": "PAID"
  },
  "delivery": {
    "address": "42, 2nd Cross, Jambusavari Dinne, JP Nagar 8th Phase",
    "lat": 12.8712,
    "lng": 77.5814,
    "provider": "borzo",
    "trackingId": "BORZO-99214-BLR"
  },
  "status": "Confirmed",
  "createdAt": "2026-10-04T12:30:00Z"
}

4. Non-Functional & Security Requirements

• Security Rules: Firestore security rules guarantee customers can read only their own orders via Firebase Auth UID. Kitchen admins must have verified records in the /admins/{uid} allowlist.
• Concurrency & High Traffic: Serverless Next.js edge runtime scales to handle festive and Sunday spikes with sub-200ms API latency.
• PWA / Mobile Performance: Fast initial bundle load (<1.5s on 4G) with offline caching for catalog images.