E-commerce Business Rule Patterns: Vouchers, Inventory, Orders, Refunds

All values are business decisions — confirm them; keep them configurable.

1. Pricing

Price precedence: flash sale price > promotion price > sale price > list price (confirm actual order).
Price displayed in cart is not locked until order placement.
Rounding (VND, no decimals); price includes VAT?

Types: % off, fixed amount off, free shipping, buy X get Y, bundle price, gift with purchase.
Conditions: min order value, eligible categories/SKUs/sellers, customer segment, first order, payment method, channel (app only).
Caps: max discount per order, total budget, usage per customer, total usage.
Stacking matrix (define explicitly!): platform voucher + seller voucher + shipping voucher + product promotion — which combine?
Order of application: product discounts → order discounts → shipping discounts (typical).
Allocation of order-level discount to line items (needed for partial returns & invoicing).
Voucher restoration when order cancelled/returned: restore or not? Before/after expiry?

ATS = on hand − reserved − safety stock.
Reservation timing: at add-to-cart (rare), at order placement (common), at payment success.
Reservation expiry for unpaid orders: [N minutes].
Flash sale: dedicated stock allocation; purchase limit per customer.
Multi-warehouse allocation rule: nearest, cheapest, single-shipment preferred.
Oversell policy: block, allow backorder, or cancel & compensate.

Split rules: by seller, by warehouse, by shipping type (bulky/standard), by pre-order item.
Cancellation: customer can cancel until status [Processing]; after that request approval.
Modification after placement (address, items) — usually not allowed or only before processing.
Auto-cancel unpaid orders after [N minutes]; auto-complete delivered orders after [N days].

Fee by weight (actual vs volumetric), zone, carrier, speed; free shipping thresholds.
Delivery attempts: [N] before RTS.
COD limits: max COD order value; COD disabled for some customers (high refusal history).

Refund to original payment method by default; COD → bank transfer / wallet / store credit.
Refund timing per method (card refunds can take days); partial refunds per line item.
Shipping fee refundable? Depends on return reason (seller fault vs change of mind).

Return window: [N days] from delivery; category exclusions (underwear, perishables, digital goods).
Required evidence (photos/unboxing video) for damage claims.
Who pays return shipping by reason.
Inspection outcome: full refund, partial refund, rejected (return to customer).

Commission by category; payment fee; service fees; penalties.
Settlement hold period after delivery/complete; reserve for returns.
Seller SLA: confirm within [N hours], ship within [N days]; late → auto-cancel + penalty.
Product listing rules: prohibited/restricted categories, mandatory attributes, brand authorization.

Points earn rate, exclusions (shipping, vouchers), points expiry, points reversal on return.

Use this with Claude: install the plugin with /plugin marketplace add lechithinh/ba-claude-skills, or read the skill source on GitHub.