Design a food delivery system

Design a **food delivery platform** (similar to common restaurant delivery apps). ## Core user stories 1. Customers can browse restaurants/menus, place an order, pay, and track delivery. 2. Restaurants receive orders, confirm/prepare them, and update status. 3. Delivery partners (couriers) receive assignments, navigate to pickup/dropoff, and update status. ## Functional requirements - Restaurant discovery (basic search/filter by location/cuisine). - Menu retrieval. - Order placement and payment. - Order lifecycle: `CREATED -> CONFIRMED -> PREPARING -> READY_FOR_PICKUP -> PICKED_UP -> DELIVERED` (include cancellation/refund paths). - Real-time-ish tracking/status updates for customers. ## Non-functional requirements - High availability for placing orders. - Idempotency for order creation/payment. - Low latency for dispatch. - Support peak traffic (e.g., lunch/dinner spikes). ## Follow-ups (mentioned by interviewer) 1. How would you design the dispatch/matching between orders and couriers? 2. How would you model and deliver real-time order status updates? 3. How would you scale search and read-heavy restaurant/menu traffic? 4. Optimization follow-up: Couriers have limited capacity/time; choose a subset of candidate orders to batch/assign to maximize value under constraints (this can resemble a **knapsack**-style optimization). Explain your approach at a high level.