Error codes
idempotency.key_reuse_mismatch
The same `Idempotency-Key` was reused with a different request body.
idempotency.key_reuse_mismatch is returned at HTTP 409.
When this fires
Idempotent endpoints fingerprint the request body when caching the original response. A second call carrying the same key but a different body is rejected with this code so the caller does not silently get back the wrong cached response.
What to do
Either send the original body verbatim under the same key, or generate a fresh key for the new request. Idempotency keys are scoped per principal × endpoint × 24h — collisions across that window are vanishingly rare for ULID-style keys.
See also
- SDK reference — the Python and TypeScript SDKs raise typed exceptions for codes in this namespace.
- Error code index — every code the runtime can return.