Billing architecture
The billing v2 mechanism — currency-routed gateways, the checkout session and its action union, first-party plan lifecycle, webhook-only entitlement granting with invoice-keyed idempotency, and boot-time config validation.
Billing checkout gate
The curl sequence that gates billing v2 runtime work — pricing reads, both checkout branches, the reads, and the dead PAYG route.
Renewals & overage
Billing v2's daily cron trio — the non-Paymob expiry sweep, the Paymob MOTO renewal engine, and the click-overage sweep — with their failure and race policies.
Billing REST surface
Billing v2's routes — the customer surface under /portal/billing, the admin direct-plan route, the gateway webhook receivers, the removed PAYG routes, and fixture-level gotchas.