Restaurant checkout and refunds

Map payment outcomes to evaluate, reserve, accrue, capture, reverse, and refund-safe adjustment.

The merchant BFF owns orchestration because it is the only layer that should see both the authenticated customer and the merchant loyalty key.

1. Preview

   Map the open cart and call orders/evaluate; reserve a selected reward before payment.
2. Resolve payment

   Reverse on failure. On settled payment, map the paid order and post accrual with the original operation key.
3. Finalize reward

   Capture the reservation against the paid order. Retry a failed operation with its original key.
4. Adjust

   Post a void or partial-refund adjustment linked to the original order with exact signed deltas.

Decide before launch whether tax, tip, service fees, gift value, comps, and delivery charges earn. Keep store-local business_date separate from event timestamps. Partial refunds reverse only earning/funding attributable to the returned amount; they are not synthetic negative purchases.

See the runnable ordering BFF on GitHub.