> For clean Markdown of any page, append .md to the page URL.
> For a complete documentation index, see https://docs.6mm.com/llms.txt.
> For AI client integration (Claude Code, Cursor, etc.), connect to the MCP server at https://docs.6mm.com/_mcp/server.

# Webhooks & Idempotency

<h2 id="webhook-headers">
  Webhook headers
</h2>

| Header            | Description                |
| ----------------- | -------------------------- |
| X-Agent-Timestamp | Unix timestamp in seconds. |
| X-Agent-Nonce     | Replay-protection nonce.   |
| X-Agent-Signature | HMAC-SHA256 signature.     |

```text
timestamp + nonce + rawBody
```

<h2 id="order-idempotency">
  Order idempotency
</h2>

| Case                     | Handling                                                   |
| ------------------------ | ---------------------------------------------------------- |
| Initial transfer request | Create one globally unique agentOrderNo.                   |
| HTTP timeout             | Query the original agentOrderNo before creating a new one. |
| PROCESSING response      | Wait for webhook or query order status.                    |
| Repeated webhook         | Deduplicate by idempotency key and final status.           |