QR DELIVERY QUEUE
Mission-critical courier dispatch and concurrency control for Amazon Now, Al-Haram Hub.
Couriers scan hub QR; instant idempotency token generated on mobile.
SELECT FOR UPDATE in PostgreSQL guarantees zero duplicate tickets.
Staff dispatch dashboard synchronizes state via WebSockets under 50ms.
Full-screen warehouse TV flashes courier number with Web Audio chime.
Operational & Technical Friction
During peak fulfillment windows, tens of couriers scan entry simultaneously. Without strict concurrency controls, duplicate sequence IDs, double-calling, and queue disputes disrupt operations.
Systemized Implementation
Constructed an atomic transaction flow in PostgreSQL using row locks and client idempotency tokens, paired with a low-latency realtime broadcasting layer.
How It Operates in Production
Developed with Next.js, TypeScript, and Supabase Realtime. Designed three distinct interfaces: an RTL mobile ticket interface for drivers, an administrative dispatch board for hub managers, and a kiosk TV display with synthesizer sound cues.
Crafted a resilient multi-screen interface (courier mobile, staff tablet, wall-mounted display) with zero-refresh WebSockets, offline warning alerts, and audio synthesize cues.
Data Flow & Infrastructure
Drivers scan a dynamic QR code generating a mobile ticket with a unique token. The request executes a PostgreSQL stored procedure with row-level locks. Supabase Realtime triggers broadcast events to operator workstations and wall-mounted TV monitors in under 50ms.