Module cash 

A cash account that cannot hold leveraged positions.

Balance locking

The account tracks locked balances per (InstrumentId, Currency) to support instruments that lock different currencies depending on order side:

• BUY orders lock quote currency (cost of purchase).
• SELL orders lock base currency (assets being sold).

Instruments that model no base currency (binary options, equities, and the other types whose base_currency() is None) have no asset to reserve, so a SELL locks nothing rather than labeling the quantity as quote money. Inventory availability for those instruments is not tracked or checked locally, including across concurrent SELLs, and is left to the venue, whose rejections arrive through the normal order lifecycle.

Callers must clear all existing locks via CashAccount::clear_balance_locked before applying new locks. This prevents stale currency entries when order compositions change.

Graceful degradation

When total locked exceeds total balance (e.g., due to venue/client state latency), the account clamps locked to total rather than raising an error. This yields zero free balance, preventing new orders while avoiding crashes in live trading.

Structs

CashAccount

Represents a cash account that cannot hold leveraged positions.