Payments and Billing

Preflight

Confirm the account, mode (TEST), price IDs, amount, and currency against the approved offer. Live charges and refunds need explicit approval per action.

Procedure

1. Checkout: the correct product, customer, and amount; cancel and return; repeated clicks; an arbitrary return_url rejected; and a checkout started by a non-owner rejected.
2. Success page: forged query parameters unlock nothing (pattern A4). Entitlement comes from verified provider state.
3. Webhooks: stripe listen + stripe trigger for success, failure, and async payment methods. Replay duplicates, reverse order, send an invalid signature, and use the wrong account or mode.
4. Cards: success, decline, insufficient funds, 3DS required, and expired.
5. Subscriptions: use test clocks for trial end, renewal, failed renewal → dunning, cancel at period end, upgrade/downgrade, and proration (Stripe billing testing).
6. Refunds and disputes: full, partial, and dispute open/won/lost. Access follows the approved policy; if there is no policy, mark it NEEDS-PRODUCT-DECISION.
7. Paying while generation or review is still incomplete.
8. Reconciliation: provider charges equal internal orders equal entitlements, with no orphans.

Exit criteria

Every money path has a provider-side proof and an internal-state proof.