Design a coffee ordering system

System Design: Coffee Ordering System

Design a system for a coffee shop (or chain) that supports ordering drinks.

Core use cases

• Customer browses menu and places an order (pickup or in-store).
• Customer customizes items (size, milk type, add-ons) and sets quantity.
• System calculates total price (including tax/discounts).
• Payment can be processed (or order marked as pay-at-store).
• Baristas see a queue of incoming orders and update status: PLACED → PAID (optional) → IN_PROGRESS → READY → COMPLETED/CANCELLED .
• Customer can see order status updates.

Constraints / scale (assume)

• Start with one store, then extend to many stores.
• Peak: thousands of orders/min across all stores.
• Status updates should feel near-real-time to customers.

What to cover

• APIs (or events) for placing orders and status updates.
• Data model for menu, orders, payments.
• High-level architecture and major services.
• Consistency, idempotency, and failure handling (e.g., retries, duplicate submits).
• How you would scale to many stores.