CHANGE REQUEST
Customers can now buy credits and spend them at any location. A credit must not be
spent twice if two locations reserve it concurrently. A room reservation may fail
after a credit hold, and a payment callback may arrive after a timeout.

Revise the previous design. Keep decisions that still hold.
Return a change-impact table covering ownership, interfaces, consistency, recovery
and rollout. Define the credit lifecycle: available, held, spent and released.
Explain how the room and credit holds are reconciled after interruption.
Finish with the smallest additional delivery slice and the decisions operations
must settle. Show why each revision is necessary; do not simply rewrite the first answer.