Building a Delivery Dispatch Backend: The Key Design Decisions

A developer built a scaled-down backend for food delivery, coordinating customers, vendors, and riders through the full order lifecycle. The project goes beyond basic CRUD, focusing on live rider matching, atomic assignment under concurrency, and idempotent payment webhooks. To prevent two orders from claiming the same rider, the system uses atomic Redis operations, with a self-expiring lock and a set-remove check that only one caller can win. For payment webhooks, unique event IDs enforced by a database constraint prevent duplicate processing when providers resend events. The author mocked the payment provider rather than using a real sandbox, reasoning that the core logic is the same regardless of provider.