Api ecn from broker request

ApiECNFromBrokerRequest

Confirms size for an ECN order, in response to a last-look request on the v1.ecn_to_broker stream.
Only applicable to SFP (kind = STABLE_PERP) instruments; only qualified market makers can hold ECN orders.

The target order is identified by order_id or client_order_id. At least one must be provided;
if both are provided they must refer to the same order, and instrument must match that order.

cumulative_confirmed_size is an absolute running total for the order and must be a multiple of the
instrument's minimum size. Its value relative to the request's cumulative_request_size decides the outcome:
- Full confirm — equal to the requested size: the held matches are executed, and the order's remaining size stays live on the book.
- Partial confirm — between the previous confirmed value and the requested size: matches are executed up to the confirmed size, and the order's unconfirmed remainder is cancelled (terminal).
- Decline — re-send the previous confirmed value, or 0 if nothing was confirmed yet: no new size executes.
- Underflow — below the previous confirmed value: the order is cancelled (ecnOrderSizeUnderflow).
- Overflow — above the requested size: the order is cancelled (ecnOrderSizeOverflow).

seq_no echoes the v1.ecn_to_broker request being answered:
- A response at the latest seq_no covers all earlier outstanding requests.
- A response to an already-superseded seq_no is ignored, so duplicate sends are safe.
- A value ahead of the latest published sequence number is rejected.

Respond before the request's expiry_time (1 second) — an unanswered request cancels the whole order (ecnOrderExpired).

Name Lite	Type	Required Default	Description
sub_account_id sa	string	True	The sub account ID that owns the ECN order being confirmed. Must match the sub account of the referenced order
order_id oi	string	True	A unique identifier for the order, generated within the GRVT backend. Required unless client_order_id is provided
client_order_id co	string	True	The client-specified identifier of the ECN order within the sub account. Required unless order_id is provided
asset a	string	True	The instrument of the ECN order. Must match the instrument of the referenced order
seq_no sn	string	True	The seq_no of the v1.ecn_to_broker message this confirmation responds to. A value ahead of the latest sequence number published for this order is rejected
cumulative_confirmed_size cc	string	True	The total size the broker has confirmed for this ECN order since inception. Must be a multiple of the instrument's minimum size increment and should not exceed the cumulative requested size