Harden residual mid-close: IOC partial fills, exchange reconcile, atomic book.

Co-authored-by: Cursor <cursoragent@cursor.com>

backend/app/sim/ledger.py

@@ -28,10 +28,12 @@ class Ledger:
         group_id: str | None = None,
         note: str = "",
         allow_negative: bool = False,
+        commit: bool = True,
     ) -> float:
         """amount>0 入账；amount<0 出账。返回余额。
 
         LIVE 实盘成交后本地账本仅作镜像，须 allow_negative=True，避免「交易所已成交、本地拒记」导致卡仓。
+        commit=False：由调用方持锁并统一提交（与持仓/残留状态同事务）。
         """
         now = int(time.time() * 1000)
         with self.db._lock:
@@ -49,15 +51,17 @@ class Ledger:
                 "INSERT INTO ledger_entries(group_id, kind, amount, balance_after, note, ts_ms) VALUES (?,?,?,?,?,?)",
                 (group_id, kind, float(amount), equity, note, now),
             )
-            self.db._conn.commit()
-        try:
-            from ..config import get_settings
-            from .funds_wallets import SimFundsWallets
+            if commit:
+                self.db._conn.commit()
+        if commit:
+            try:
+                from ..config import get_settings
+                from .funds_wallets import SimFundsWallets
 
-            if get_settings().is_sim:
-                SimFundsWallets(self.db).mirror_cash(float(amount), kind=kind)
-        except Exception:
-            pass
+                if get_settings().is_sim:
+                    SimFundsWallets(self.db).mirror_cash(float(amount), kind=kind)
+            except Exception:
+                pass
         return equity
 
     def reset_equity(self, amount: float, *, note: str = "重置模拟资金") -> float: