Affirmatively accepts the immutable authorization digest for the selected rail. Device, challenge, and provider-authentication evidence are not accepted by this operation.

Returns 409 InvalidStateTransition with detailCode payments.PaymentMethodCaptureIncomplete when the hosted capture has not completed, and payments.PaymentIntentNotConfirmed when the Invoice collection already closed without this Intent. Both are deterministic conflicts: no retry can clear them.

Every post-create mutation requires If-Match; a stale value returns 412 PreconditionFailed with detailCode payments.StaleInvoicePaymentIntent carrying the current ETag. Reusing an Idempotency-Key with a different body returns 409 IdempotencyKeyConflict with detailCode payments.IdempotencyKeyConflict. An upstream response that cannot be projected onto this contract returns 503 ServiceUnavailable with detailCode payments.UpstreamContractViolation.