One-Time Purchase

A single charge rather than a recurring subscription. The subscriber confirms with a one-time code, exactly as in the PIN flow: what differs is that nothing ongoing is created.

Why the alt block earns its place: eligibility is checked at issue and again at verify. The early check means a purchase that cannot complete never costs the subscriber a message; the late one catches a subscriber who became ineligible in between. Additive, not moved: an SP reading only the first would build the wrong retry behaviour.