Recording a sale from the phone app — no duplicates

When you record a sale from the phone app you see the total first — the system prices it and quotes delivery from your own catalog, you never type a number. If the connection drops while saving, sending again never creates a second order — every attempt carries its own key, and a repeat with the same key returns the first result. This is answer-only for the AI, which never records a sale itself — a real sale reserves stock and the seller must see the priced review screen before confirming it.