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

# Idempotency

> Retry order creation without accidentally placing a duplicate order.

Every order creation and position-close request must include an
`Idempotency-Key` header. This includes `POST /v1/orders`,
`POST /v1/twap-orders`, `POST /v1/scaled-orders`, and
`POST /v1/positions/{position_id}/close`. Use a unique value for each intended
operation and reuse that same value only when retrying the identical request
on the same endpoint.

```http theme={null}
Idempotency-Key: 01J6Y6K4ZKQ9R0M3YQ59P8M0PC
```

The key may contain printable ASCII characters and may be up to 128 characters.
Funding Perpetuals binds it to the API key, endpoint, and a hash of the request.
The binding is written in the same database transaction as the order, so two
concurrent retries cannot create two accepted orders.

The first accepted request returns `201 Created`. A retry with the same key and
payload returns `200 OK` with the order's current state. That state may have
advanced since the first response, for example from pending to filled, so use
the returned `status` as the source of truth.

A trading-rule rejection returns `422` on both the original request and every
matching retry. The error keeps the original `order_id`, rule code, and details,
so a lost response cannot turn a rejected placement into an apparent success.

Reusing an idempotency key with a different account, market, side, size, or
other order field is rejected. Generate keys with enough entropy, such as a
UUIDv4 or ULID, and retain them alongside your local order record.