Shop-owned activities on one SKU, concrete groups with an
open/successful/expired/cancelled lifecycle, and one paid membership row per
paid order. Checkout accepts a single-SKU quantity-1 intent, snapshots the group
price and identity on the pending order, and opens or references a group; a paid
seat is claimed only at payment, which locks the group and fills it exactly at
capacity.
Pending-payment cancellation restores SKU stock only and never rolls back paid
seats; an unpaid opener cancelling closes a still-empty group. Coupons are
refused on a group shop order, and the flash-sale exclusion is now enforced in
both directions because the activity table exists, which activates the guard
add-flash-sales shipped dormant. The activity column names follow the contract
recorded in this change's design.
Surfaces (shop-admin, mall) and seeding follow.
james
a7bc476251