API version policy

Versioned paths protect live integrations. Existing v1 behavior is preserved while new capabilities are added under v2.

• Additive response fields and new endpoints may be released within v2.
• Clients must ignore response fields they do not recognize.
• Breaking request or response changes require a new versioned path.
• No v1 retirement date is currently declared.
• Any future deprecation date and migration action will be published in the changelog before enforcement.

Do not replace a timed-out v2 checkout with a v1 checkout. Reconcile the idempotent v2 result first.