对齐次日交易信号基线与基准收益起点

crates/fidc-core/src/engine.rs

@@ -91,6 +91,9 @@ impl Default for ProcessEventRetention {
 
 #[derive(Debug, Clone, Serialize, Deserialize)]
 pub struct DailyEquityPoint {
+    /// Close-of-signal-day cash baseline before lagged trading begins.
+    #[serde(default, skip_serializing_if = "std::ops::Not::not")]
+    pub signal_baseline: bool,
     #[serde(with = "date_format")]
     pub date: NaiveDate,
     pub cash: f64,
@@ -109,6 +112,14 @@ pub struct DailyEquityPoint {
     pub diagnostics: String,
 }
 
+impl DailyEquityPoint {
+    pub fn benchmark_reference_close(&self) -> f64 {
+        if self.signal_baseline { self.benchmark_close }
+        else if self.benchmark_prev_close.is_finite() && self.benchmark_prev_close > f64::EPSILON { self.benchmark_prev_close }
+        else { self.benchmark_close }
+    }
+}
+
 #[derive(Debug, Clone)]
 pub struct BacktestResult {
     pub strategy_name: String,
@@ -334,7 +345,7 @@ impl BacktestResult {
         let mut previous_benchmark = self
             .equity_curve
             .first()
-            .map(|point| point.benchmark_prev_close)
+            .map(DailyEquityPoint::benchmark_reference_close)
             .unwrap_or_default();
         for point in &self.equity_curve {
             let point_nav = if point.unit_nav.is_finite() && point.unit_nav > 0.0 {
@@ -2202,6 +2213,7 @@ where
                 previous_external_cash_flow_total = portfolio.external_cash_flow_total();
 
                 result.equity_curve.push(DailyEquityPoint {
+                    signal_baseline: true,
                     date: execution_date,
                     cash: aggregate_cash,
                     market_value: aggregate_market_value,
@@ -3369,6 +3381,7 @@ where
             previous_external_cash_flow_total = portfolio.external_cash_flow_total();
 
             result.equity_curve.push(DailyEquityPoint {
+                signal_baseline: false,
                 date: execution_date,
                 cash: aggregate_cash,
                 market_value: aggregate_market_value,

crates/fidc-core/src/metrics.rs

@@ -108,13 +108,7 @@ pub fn compute_backtest_metrics(
     };
 
     let trade_days = equity_curve.len();
-    let benchmark_start = if first_point.benchmark_prev_close.is_finite()
+    let benchmark_start = first_point.benchmark_reference_close();
-        && first_point.benchmark_prev_close > f64::EPSILON
-    {
-        first_point.benchmark_prev_close
-    } else {
-        first_point.benchmark_close
-    };
     let explicit_unit_nav = equity_curve.iter().any(|point| {
         point.external_cash_flow.abs() > f64::EPSILON
             || (point.unit_nav.is_finite()
@@ -780,6 +774,7 @@ mod tests {
         benchmark_prev_close: f64,
     ) -> DailyEquityPoint {
         DailyEquityPoint {
+            signal_baseline: false,
             date: NaiveDate::parse_from_str(date, "%Y-%m-%d").unwrap(),
             cash: total_equity,
             market_value: 0.0,
@@ -804,11 +799,21 @@ mod tests {
         assert!((metrics.benchmark_cumulative_return - expected).abs() < 1e-12);
     }
 
+    #[test]
+    fn signal_baseline_uses_same_close_for_strategy_and_benchmark() {
+        let mut baseline=equity_point("2026-09-04",100.0,4548.0499,4552.5784);
+        baseline.signal_baseline=true;
+        let curve=vec![baseline,equity_point("2026-09-08",104.0,4558.7371,4575.0245)];
+        let metrics=compute_backtest_metrics(&curve,&[],&[],&[],100.0,None).unwrap();
+        assert!((metrics.benchmark_cumulative_return-(4558.7371/4548.0499-1.0)).abs()<1e-12);
+    }
+
     #[test]
     fn external_cash_flow_is_excluded_from_return_and_reported_separately() {
         let curve = vec![
             equity_point("2025-01-02", 100.0, 100.0, 100.0),
             DailyEquityPoint {
+                signal_baseline: false,
                 date: NaiveDate::from_ymd_opt(2025, 1, 3).unwrap(),
                 cash: 220.0,
                 market_value: 0.0,