Lists, maps, and pick can keep moving while outside systems wobble.
Pick queue can keep running; paid sales retry when the register link returns.
Live Concierge waits for the processor — pay-at-store is lab/training only.
Last known stock stays visible; managers can mark unavailable.
Scoped logins and trails for OOS, imports, and order status.
Start with a pilot checklist, not a big-bang cutover.