# Playbook: Payment / Unlock / Subscription

## Steps

1. Terms: Order, Payment, Unlock, Subscription, Membership, VIP (`.ai/domain.md`)
2. Server creates Order with amount/currency/product ref
3. Client never sets final price unilaterally
4. Payment callback verifies signature + idempotency
5. On success: grant Membership or Unlock in service transaction
6. Report access checks Membership/Unlock server-side every time
7. Migration for `payment_order` / related tables
8. Tests: double callback, wrong amount, replay
9. No secrets in frontend
10. Feature checklist + security review