The shelf is shorter than the promise

transcript

An order is paid for. Five units are promised from one warehouse. Then a stock count finds two of them broken. The shelf holds three. What does the system do now?

Fulfil ships the smaller of two numbers. What is owed, and what is there. Three units go out from this warehouse today. Two units are still owed. They stay reserved, not forgotten.

The order moves from paid to partially shipped. That is a normal state. When stock arrives, the next fulfil sends the rest. Then it is shipped.

On hand is the shelf. It is what is physically there. Reserved is the promise. It is what orders were told. They can drift apart, so the design keeps both numbers.

The remaining two units stay on the reservation. They are owed, not lost. New stock arrives. The warehouse receives four units. The next fulfil sends the last two. Reserved drops to zero.

Reality wins over the promise. Ship what is there, and keep the rest owed.

The full design is in the lecture. Plans, expiry, and an order state machine.