Fixed AccountMarginExceeded error

RELEASES.md

@@ -31,6 +31,7 @@ Released on TBD (UTC).
 - Fixed `RiskEngine` cumulative notional calculations for margin accounts (was incorrectly using base currency when selling)
 - Fixed selling `Equity` instruments with `CASH` account and `NETTING` OMS incorrectly rejecting (should be able to reduce position)
 - Fixed Databento bars decoding (was incorrectly applying display factor)
+- Fixed `AccountMarginExceeded` error condition (margin must actually be exceeded now, and can be zero)
 
 ---
 

nautilus_trader/accounting/accounts/margin.pyx

@@ -466,7 +466,7 @@ cdef class MarginAccount(Account):
 
         cdef double total_free = current_balance.total.as_f64_c() - total_margin
 
-        if total_free <= 0.0:
+        if total_free < 0.0:
             raise AccountMarginExceeded(
                 balance=current_balance.total.as_decimal(),
                 margin=Money(total_margin, currency).as_decimal(),

nautilus_trader/accounting/manager.pyx

@@ -559,12 +559,12 @@ cdef class AccountsManager:
                 new_free = balance.free.as_f64_c() + pnl.as_f64_c()
                 total = Money(new_total, pnl.currency)
                 free = Money(new_free, pnl.currency)
-                if new_total < 0:
+                if new_total < 0.0:
                     raise AccountBalanceNegative(
                         balance=total.as_decimal(),
                         currency=pnl.currency,
                     )
-                if new_free <= 0:
+                if new_free < 0.0:
                     raise AccountMarginExceeded(
                         balance=total.as_decimal(),
                         margin=balance.locked.as_decimal(),