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

# Idempotency

> Safe retries for mutating operations.

For mutating endpoints (`POST`, `PATCH`, `DELETE`), send:

```http theme={null}
Idempotency-Key: <unique_operation_key>
```

Behavior:

* Same key + same payload: original response is replayed.
* Same key + different payload: `409` conflict.
* In-progress duplicate: `409` conflict.

Use deterministic keys from your agent action IDs for safe retries.