feat: expose platform-neutral ledger projection

src/quant_engine/execution.py

@@ -422,6 +422,50 @@ class ExecutionSimulationResult:
         ]
         return pd.DataFrame(rows, columns=columns)
 
+    @property
+    def ledger_frame(self) -> pd.DataFrame:
+        """返回稳定的日频 Ledger 投影，不附加运行元数据或写数据库。"""
+        columns = [
+            "trade_date",
+            "portfolio_value",
+            "nav",
+            "pnl",
+            "pnl_pct",
+            "position_value",
+            "cash",
+            "turnover",
+        ]
+        previous_value = self.initial_cash
+        rows: list[dict[str, float | str]] = []
+        daily_returns = self.daily_returns
+        for index, (position, daily) in enumerate(
+            zip(self.positions, self.daily_executions, strict=True)
+        ):
+            daily_turnover = sum(
+                execution.executed_value
+                for execution in daily.executions
+                if execution.quantity > 0
+            )
+            turnover_rate = daily_turnover / daily.nav_before if daily.nav_before > 0 else 0.0
+            rows.append(
+                {
+                    "trade_date": position.date,
+                    "portfolio_value": position.portfolio_value,
+                    "nav": (
+                        position.portfolio_value / self.initial_cash
+                        if self.initial_cash != 0
+                        else 0.0
+                    ),
+                    "pnl": position.portfolio_value - previous_value,
+                    "pnl_pct": float(daily_returns.iloc[index]),
+                    "position_value": position.portfolio_value - position.cash,
+                    "cash": position.cash,
+                    "turnover": turnover_rate,
+                }
+            )
+            previous_value = position.portfolio_value
+        return pd.DataFrame(rows, columns=columns)
+
     @property
     def total_costs(self) -> float:
         """汇总实际成交产生的成本。"""