{"id":"payment-idempotency-is-key-based","text":"Idempotency is enforced by mapping client-provided keys to payment IDs in `_idempotency`; a repeated key returns the original `Payment` without re-processing","truth_value":"IN","source":"entries/2026/06/05/payment-system-payment_system.md","source_url":"","source_hash":"","justifications":[],"dependents":["idempotency-keys-ignore-payload-content"],"metadata":{},"created_at":"","updated_at":"","reviewed_at":"","verified_at":"","retracted_at":"","explanation":{"steps":[{"node":"payment-idempotency-is-key-based","truth_value":"IN","reason":"premise"}]}}