| 18 | | **Coupon** and Discount serve distinct purposes in the billing model. A **Discount** is an optional reduction applied directly to an individual ** |
| | 18 | **Coupon** and Discount serve distinct purposes in the billing model. A **Discount** is an optional reduction applied directly to an individual **!ShopItem**. A **Coupon** is a promotional code applied at the **Invoice** level, carrying validation rules such as validity dates (“valid_from”, “valid_to”), a minimum order total (“min_total”), usage limits (“usage_limit”), and an “is_active” status flag. This separation reflects two different business scenarios: a staff member marking down a specific item with a discount versus a customer applying a promotional code to their whole invoice. |
