Treat a sale, reservation, return, and counter purchase as separate stock events. Update one shared count after each confirmed change, and put an expiry time on unpaid holds so another seller knows whether the unit is still allocated.
During a rush, focus on goods sold through more than one channel. A counter tally can miss a phone order or an online reservation; reconcile the remaining pieces at planned checkpoints instead of relying on an earlier count. Keep supplier deliveries marked as incoming until someone checks the quantity received.
If the count is uncertain, pause the offer or say availability needs confirmation. Resume only after the shelf and record agree, and give staff a simple way to flag changes they cannot enter themselves. A short adjustment note can identify who changed the quantity and when, making the next handover easier.
