| Property | Contract |
|---|---|
| Header | Idempotency-Key. |
| Format | 16–128 characters matching [A-Za-z0-9._:-]. |
| Coverage | Developer, SCIM, and all session-authenticated organization mutations. |
| Storage | Only a namespace-scoped hash and request fingerprint. |
| Replay | Equivalent completed requests return a safe replay classification without one-time secrets. |
| Reuse | A changed request with the same key returns idempotency_key_reused. |
| Concurrency | An in-progress request returns a bounded retry hint. |
RESOURCES
Idempotency
Use idempotency keys for supported developer, SCIM, and organization mutations so lost responses do not create duplicate resources or deliveries.