perf: isolate ordered selection hot path

crates/fidc-core/src/platform_expr_strategy.rs

@@ -10122,6 +10122,51 @@ impl PlatformExprStrategy {
         // complete ranking for replacement limiting, select directly from the
         // ordered stream instead of materializing a second candidate vector.
         if self.rank_reuses_market_cap_order() && self.config.daily_replacement_limit == 0 {
+            let selected = self.select_market_cap_ordered_symbols(
+                ctx,
+                date,
+                universe_factor_date,
+                stock_factor_date,
+                day,
+                band_low,
+                band_high,
+                limit,
+                universe_symbol_ids,
+                &mut diagnostics,
+            )?;
+            return Ok((selected, diagnostics, risk_decisions));
+        }
+
+        let selected = self.select_ranked_symbols(
+            ctx,
+            date,
+            universe_factor_date,
+            stock_factor_date,
+            day,
+            band_low,
+            band_high,
+            limit,
+            universe_symbol_ids,
+            &mut diagnostics,
+        )?;
+        Ok((selected, diagnostics, risk_decisions))
+    }
+
+    #[inline(never)]
+    #[allow(clippy::too_many_arguments)]
+    fn select_market_cap_ordered_symbols(
+        &self,
+        ctx: &StrategyContext<'_>,
+        date: NaiveDate,
+        universe_factor_date: NaiveDate,
+        stock_factor_date: NaiveDate,
+        day: &DayExpressionState,
+        band_low: f64,
+        band_high: f64,
+        limit: usize,
+        universe_symbol_ids: Vec<u32>,
+        diagnostics: &mut Vec<String>,
+    ) -> Result<Vec<String>, BacktestError> {
         let execution_day = ctx.data.daily_snapshot_view(date);
         let universe_factor_day = ctx.data.daily_snapshot_view(universe_factor_date);
         let factor_day = ctx.data.daily_snapshot_view(stock_factor_date);
@@ -10154,7 +10199,7 @@ impl PlatformExprStrategy {
                 day,
                 symbol,
                 &stock,
-                    &mut diagnostics,
+                diagnostics,
             )? {
                 selected.push(factor.symbol.clone());
                 if selected.len() >= limit {
@@ -10162,22 +10207,7 @@ impl PlatformExprStrategy {
                 }
             }
         }
-            return Ok((selected, diagnostics, risk_decisions));
-        }
-
-        let selected = self.select_ranked_symbols(
-            ctx,
-            date,
-            universe_factor_date,
-            stock_factor_date,
-            day,
-            band_low,
-            band_high,
-            limit,
-            universe_symbol_ids,
-            &mut diagnostics,
-        )?;
-        Ok((selected, diagnostics, risk_decisions))
+        Ok(selected)
     }
 
     #[inline(never)]