ucp-discount

Discount allocation tracking distributes applied promo code amounts across individual line items, ensuring the sum of all allocations equals the total applied discount amount without pricing discrepancies.

You can apply multiple discount codes in one UCP checkout session by submitting several buyer-provided promo codes, validating each against UCP specifications, and updating the order total accordingly.

When an expired or invalid discount code is submitted in a UCP checkout, the validation process catches the error based on UCP error codes and prevents the invalid discount from applying to the order.

Managing UCP discount codes requires no external dependencies, as the validation and allocation logic operates independently within the Universal Commerce Protocol checkout process.

Discount allocation mismatches occur when the sum of line item allocations does not equal the applied discount amount, violating the allocation invariant that this checkout process is designed to enforce.