# Amend (modify) order

**PATCH /trading/accounts/{account_id}/orders**

Modify order parameters (Price/Qty).
  - **Targeting:** Requires `market_id` and either `order_id` OR `client_order_id`.
  - **Stable Identity:** `client_order_id` is immutable and used only for targeting.
  - **Priority Logic:**
      * price change OR qty increase → priority reset (order repositioned)
      * qty decrease (and unchanged price) → priority preserved
  - **Idempotency:** Guaranteed by `Idempotency-Key`.



## Servers
- Production: https://api.example.com/v1 (Production)
- Sandbox: https://sandbox.api.example.com/v1 (Sandbox)


## Authentication methods
- Api key auth


## Parameters
### Headers

- **PRE-ACCESS-KEY** (string)
  Broker access key identifier.

- **PRE-ACCESS-SIGNATURE** (string)
  Keyed BLAKE2b-256 signature (hex lowercase, 64 characters).

- **PRE-ACCESS-TIMESTAMP** (string(date-time))
  RFC3339 timestamp with milliseconds (e.g., 2025-10-30T06:00:34.075Z). Must be within clock_skew_tolerance (default 5m) of server time.

- **Idempotency-Key** (string)
  Stable idempotency token reused on retries. Reuse with identical payload => 202. Reuse with different payload => 409 idempotency_key_mismatch.

- **Correlation-Id** (string)
  Optional UUIDv7 correlation identifier (lowercase). Must match RFC4122 UUIDv7 (version nibble '7', variant 8|9|a|b). If present but invalid → 422 invalid_correlation_id (error_code).


### Path parameters

- **account_id** (string)
  Broker-supplied account identifier; length 1..128; charset [A-Za-z0-9._~-].



### Body: application/json (object)

- **market_id** (string)
  Required for routing

- **order_id** (string(uuid))
  Target order ID (preferred)

- **client_order_id** (string)
  Target client order ID (fallback)

- **price** (object)

- **qty** (object)



## Responses
### 200
Amend command accepted

#### Body: application/json (object)
- **order_id** (string(uuid))
  Internal Order ID (if known or generated).

- **client_order_id** (string)
  Client-supplied identifier (if provided).


### 202
Idempotent replay

#### Body: application/json (object)
- **order_id** (string(uuid))
  Internal Order ID (if known or generated).

- **client_order_id** (string)
  Client-supplied identifier (if provided).


### 404
Resource not found

#### Body: application/json (object)
- **error_code** (string)

- **message** (string)

- **details** (object)


### 409
Idempotency-Key reused with different payload

#### Body: application/json (object)
- **error_code** (string)

- **message** (string)

- **details** (object)


### 422
Validation / semantic error

#### Body: application/json (object)
- **error_code** (string)

- **message** (string)

- **details** (object)


### 503
Backpressure / temporary unavailability

#### Body: application/json (object)
- **error_code** (string)

- **message** (string)

- **details** (object)



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