Revert "修正次日开盘目标市值换股语义"

This reverts commit 438757ab54.

crates/fidc-core/src/broker.rs

@@ -427,10 +427,11 @@ where
         symbol: &str,
         snapshot: &crate::data::DailyMarketSnapshot,
     ) -> f64 {
-        if self.matching_type == MatchingType::NextBarOpen {
-            // The target budget is frozen on the signal day, but the broker can only
-            // convert that budget to shares once the next session's open is visible.
-            return self.sizing_price(snapshot);
+        if self.matching_type == MatchingType::NextBarOpen
+            && snapshot.prev_close.is_finite()
+            && snapshot.prev_close > 0.0
+        {
+            return snapshot.prev_close;
         }
         if self.aiquant_execution_rules && self.execution_price_field == PriceField::Last {
             let start_cursor = self
@@ -7153,7 +7154,7 @@ mod tests {
     }
 
     #[test]
-    fn next_open_target_value_valuation_uses_execution_open() {
+    fn next_open_target_value_valuation_uses_previous_close() {
         let date = chrono::NaiveDate::from_ymd_opt(2025, 1, 2).expect("valid date");
         let broker = BrokerSimulator::new_with_execution_price(
             ChinaAShareCostModel::default(),
@@ -7180,7 +7181,7 @@ mod tests {
 
         assert_eq!(
             broker.target_value_valuation_price(date, &data, "000001.SZ", snapshot),
-            11.0
+            10.0
         );
     }