A deterministic idempotency key for a checkout attempt. The SAME cart under the same scope (principal) yields
the SAME key, so a retried "create payment intent" REUSES the existing intent instead of charging twice; a
changed cart yields a new key. Thread this into the processor's idempotency-key header.
A deterministic idempotency key for a checkout attempt. The SAME cart under the same scope (principal) yields the SAME key, so a retried "create payment intent" REUSES the existing intent instead of charging twice; a changed cart yields a new key. Thread this into the processor's idempotency-key header.