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

# Idempotency

> Idempotent invoice creation behavior.

## Invoice creation

`POST /v1/invoices` is idempotent on `(store_id, external_order_id)`:

* Existing match → returns the same invoice with HTTP `201`
* Same `external_order_id` on a **different** Woo integration → HTTP `409` (`EXTERNAL_ORDER_INTEGRATION_CONFLICT`)

## Webhook deliveries

Dedupe on `X-Meum-Event-Id`. See [Webhooks overview](/webhooks/overview).