perf: retain faster stable universe sort

crates/fidc-core/src/platform_expr_strategy.rs

@@ -9214,17 +9214,6 @@ impl PlatformExprStrategy {
         .0
     }
 
-    #[inline]
-    fn eligible_universe_market_cap_order(
-        left: &EligibleUniverseSnapshot,
-        right: &EligibleUniverseSnapshot,
-    ) -> std::cmp::Ordering {
-        left.market_cap_bn
-            .partial_cmp(&right.market_cap_bn)
-            .unwrap_or(std::cmp::Ordering::Equal)
-            .then_with(|| left.symbol.cmp(&right.symbol))
-    }
-
     fn selection_universe_and_risk_decisions_with_options(
         &self,
         ctx: &StrategyContext<'_>,
@@ -9307,7 +9296,12 @@ impl PlatformExprStrategy {
                 free_float_cap_bn,
             });
         }
-        rows.sort_unstable_by(Self::eligible_universe_market_cap_order);
+        rows.sort_by(|left, right| {
+            left.market_cap_bn
+                .partial_cmp(&right.market_cap_bn)
+                .unwrap_or(std::cmp::Ordering::Equal)
+                .then_with(|| left.symbol.cmp(&right.symbol))
+        });
         (rows, decisions)
     }
 
@@ -14262,36 +14256,6 @@ mod tests {
         assert!(!PlatformExprStrategy::new(cfg).rank_reuses_market_cap_order());
     }
 
-    #[test]
-    fn eligible_universe_unstable_sort_preserves_market_cap_symbol_total_order() {
-        let mut rows = vec![
-            EligibleUniverseSnapshot {
-                symbol: "000003.SZ".to_string(),
-                market_cap_bn: 2.0,
-                free_float_cap_bn: 1.0,
-            },
-            EligibleUniverseSnapshot {
-                symbol: "000002.SZ".to_string(),
-                market_cap_bn: 1.0,
-                free_float_cap_bn: 1.0,
-            },
-            EligibleUniverseSnapshot {
-                symbol: "000001.SZ".to_string(),
-                market_cap_bn: 1.0,
-                free_float_cap_bn: 1.0,
-            },
-        ];
-
-        rows.sort_unstable_by(PlatformExprStrategy::eligible_universe_market_cap_order);
-
-        assert_eq!(
-            rows.iter()
-                .map(|row| (row.market_cap_bn, row.symbol.as_str()))
-                .collect::<Vec<_>>(),
-            vec![(1.0, "000001.SZ"), (1.0, "000002.SZ"), (2.0, "000003.SZ"),]
-        );
-    }
-
     #[test]
     fn current_rolling_helpers_do_not_load_factor_maps_or_decision_rollings() {
         let mut cfg = PlatformExprStrategyConfig::microcap_rotation();