Checkout item preparation

The Lifecycle

Transitions Explained

Selections carry assessment results rather than an independently enforced state machine. Changes reset validation, preview records advice or blockers, holds record preparation and expiry marks stale. Placement reassesses the selection and captures fresh attestation as frozen.

What Cannot Happen

A placed cart cannot be edited. Stored problems do not create a permanent refusal: placement's fresh preparation determines whether the item can proceed.

Concurrency and Timing

Cart writes use locks and version checks. The reservation sweep records lapsed holds once per minute, while placement always obtains authoritative preparation.