Peak checkout
A store system is tested in the seconds at the till, not in a back-office report. Goods are already on the belt; the cashier must scan, reprice, identify the member, compute promotions, take payment, and issue a receipt. Any stall queues to the door. We walk a full peak shift with the manager and cashiers and record the real path: how weighed items are entered, how a held ticket is recovered, how a member without a phone number is found, how two promotion layers stack, whether selling continues offline. Those details belong on the scope list more than an architecture slide.
One ledger online and off
Splitting online and offline is the usual retail trap. The mall has one member file, the store another card, stock is counted twice, a private-domain campaign oversells, and returns never match. We unify identity on mobile number or WeChat Pay, migrate stored value and points onto the books, and treat physical store stock as source of truth—mall holds, pickup redemption, and delivery outbound share one decrement. Promotions are not a cashier speech: spend-and-save, second-item half, member price, and coupon order compute at the till, the receipt prints the breakdown, discount rights are role-limited, and later reconciling has a basis.
Weak networks and devices
Store conditions are requirements, not a go-live surprise. Many stores have no stable leased line; guns, scales, drawers, printers, and customer displays are already there. The system must open tickets locally on a weak network and backfill when it recovers, and it must talk to existing peripherals instead of demanding a full swap. Pilots are usually one or two high-peak stores: shift close, day close, and counts run through before the rest of the chain. Training is cashiers and managers, not HQ IT—if the floor cannot use it, it is not live.
Shift close and counts
Cash, scan-to-pay, stored value, and coupon redemptions must compose one shift-close sheet; a fen of difference traces to a line. If the handover does not match, calculators come back the next day. Electronic shelf labels, weigh barcodes, and tare on loose goods belong on the integration list so a scale code the till does not recognize is not a launch-day discovery. Conflicting promotion calendars and whether member price and coupons stack are nailed with a few real receipts in the design.
Operating facts
HQ wants facts you can replay: basket size, attach, repurchase, stockouts, shrink, daypart. Those numbers must come from one stream of tickets, not a nightly form the manager fills. We make day close, count variance, and waste approval traceable, and operating analysis drills from category and store to the document. A retail system is not software that can sell—it is one set of books the store will use and HQ can trust.