API analysis check

Idempotency defines how repeated requests avoid duplicate charges.

A larger button: This does not prevent duplicate processing.

A new status colour: Colour does not change transaction semantics.

Failure handling is part of the contract and affects customer and operational outcomes.

A logo file: A logo is unrelated to API behaviour.

A sprint goal: A sprint goal does not specify the integration.

Stable IDs support traceability, callbacks and reconciliation.

The user's screen size: Screen size cannot reconcile transactions.

The designer's prototype: A prototype does not provide transaction identity.