Closed-book card for day 84. This file is the interviewer. It is not a worked example.
Do not open the Phase 5 lessons while this timer is running. Do not scroll past the attempt barrier on the day 84 page. This is not an SLO poster, cost sheet, or live-migration lesson. Near minute 25, expect a region or the location store to fail.
Design a delivery dispatch system.
Customers request a pickup and dropoff. The system offers the job to nearby couriers, assigns one, and tracks the delivery. Couriers move. Near minute 25 your interviewer will take something away — a region or the live location store. Keep designing through that.
You have 35 minutes. Blank page. No notes.