> ## Documentation Index
> Fetch the complete documentation index at: https://docs.antonpayments.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Idempotency and Retries

> Safely retry Intelligence create requests.

The `Idempotency-Key` header is **required** on authenticated `POST /v1/intelligence/evaluations` calls (omitting it returns `400 missing_idempotency_key`). On the anonymous public test surface it is optional but recommended.

```http theme={}
Idempotency-Key: intel-payee-crm-84012-v1
```

If a network timeout occurs, retry the exact same request with the same key. Anton returns the original evaluation when the operation has already completed — the evaluation is not re-run and no duplicate is persisted. A replay while the first attempt is still processing returns `409 idempotency_in_flight`; wait briefly and retry with the same key.

The JSON body also accepts `idempotency_key` for testing, but the header is the enterprise contract. If both are present, the header wins.

Standard idempotency semantics apply — 24-hour key retention, `409 idempotency_conflict` on key reuse with a different body, `X-Idempotent-Replayed: true` on replays. See [Idempotency](/api-reference/idempotency).