Function account_balance_from_lighter_asset 

pub fn account_balance_from_lighter_asset(
    asset: &LighterAsset,
) -> Result<AccountBalance>

Builds the per-asset [AccountBalance] for one Lighter wallet entry.

Lighter is a unified-margin venue: spot-side balance and perp-side margin_balance are both deployable equity. The split shows where the money currently sits, not whether it’s usable. The only true lock on the trading side is locked_balance (resting spot orders); perp margin currently in use is tracked separately via [MarginBalance], not via AccountBalance.locked.

We map:

• total = balance + margin_balance: every unit of that currency the account owns at the venue
• locked = locked_balance: only spot-order reservations
• free = total - locked (derived by from_total_and_locked): all deployable equity, whether currently sitting on spot or perp

Perp-side margin currently allocated to positions is not folded into locked. It lives on [MarginBalance] and the portfolio’s risk engine consumes it from there. See margin_balance_from_user_stats.

Errors

Returns an error if AccountBalance::from_total_and_locked rejects the computed values.