diff --git a/crates/fidc-core/src/platform_expr_strategy.rs b/crates/fidc-core/src/platform_expr_strategy.rs
index 53029e7..386a258 100644
--- a/crates/fidc-core/src/platform_expr_strategy.rs
+++ b/crates/fidc-core/src/platform_expr_strategy.rs
@@ -2830,6 +2830,13 @@ impl PlatformExprStrategy {
         working_symbols.union(slot_blocking_symbols).count()
     }
 
+    fn should_block_partial_exit_residual_slot(
+        trading_ratio: f64,
+        defer_execution_risk: bool,
+    ) -> bool {
+        trading_ratio < 1.0 && !defer_execution_risk
+    }
+
     fn remaining_buy_cash_active_value(
         &self,
         ctx: &StrategyContext<'_>,
@@ -9276,7 +9283,11 @@ impl Strategy for PlatformExprStrategy {
         let mut deferred_daily_target_values = BTreeMap::<String, f64>::new();
         let mut pending_full_close_symbols = BTreeSet::<String>::new();
         let mut slot_blocking_symbols = BTreeSet::<String>::new();
-        let should_block_partial_exit_residual_slot = trading_ratio < 1.0;
+        // Lagged execution only freezes the T-day intent. Whether an exit leaves a
+        // residual position is an execution-day fact and must not consume a T+1
+        // replacement slot before the sell leg is actually matched.
+        let should_block_partial_exit_residual_slot =
+            Self::should_block_partial_exit_residual_slot(trading_ratio, defer_execution_risk);
         let interleaved_pending_full_close_symbols = BTreeSet::<String>::new();
         let risk_level_forced_exit_time = self.risk_level_forced_exit_time();
         self.pending_full_close_symbols.retain(|symbol| {
@@ -9552,7 +9563,7 @@ impl Strategy for PlatformExprStrategy {
                     target_value: 0.0,
                     reason: "pending_full_close_exit".to_string(),
                 });
-                if daily_top_up_pending_buy_value > 0.0 {
+                if daily_top_up_pending_buy_value > 0.0 && should_block_partial_exit_residual_slot {
                     slot_blocking_symbols.insert(position.symbol.clone());
                 }
                 self.forget_position_entry_date(&position.symbol);
@@ -9576,7 +9587,9 @@ impl Strategy for PlatformExprStrategy {
                             self.pending_full_close_symbols.remove(&position.symbol);
                         } else {
                             pending_full_close_symbols.insert(position.symbol.clone());
-                            slot_blocking_symbols.insert(position.symbol.clone());
+                            if should_block_partial_exit_residual_slot {
+                                slot_blocking_symbols.insert(position.symbol.clone());
+                            }
                             self.pending_full_close_symbols
                                 .insert(position.symbol.clone());
                         }
@@ -9643,7 +9656,7 @@ impl Strategy for PlatformExprStrategy {
                     self.pending_full_close_symbols.remove(&position.symbol);
                 } else {
                     exit_symbols.insert(position.symbol.clone());
-                    if trading_ratio < 1.0 {
+                    if should_block_partial_exit_residual_slot {
                         slot_blocking_symbols.insert(position.symbol.clone());
                     }
                     order_intents.push(OrderIntent::TargetValue {
@@ -9726,7 +9739,7 @@ impl Strategy for PlatformExprStrategy {
                     target_value: 0.0,
                     reason: "stop_loss_exit".to_string(),
                 });
-                if daily_top_up_pending_buy_value > 0.0 && trading_ratio < 1.0 {
+                if daily_top_up_pending_buy_value > 0.0 && should_block_partial_exit_residual_slot {
                     slot_blocking_symbols.insert(position.symbol.clone());
                 }
                 self.forget_position_entry_date(&position.symbol);
@@ -21900,6 +21913,13 @@ mod tests {
         );
     }
 
+    #[test]
+    fn platform_lagged_exit_does_not_reserve_replacement_slot_before_execution() {
+        assert!(PlatformExprStrategy::should_block_partial_exit_residual_slot(0.5, false));
+        assert!(!PlatformExprStrategy::should_block_partial_exit_residual_slot(0.5, true));
+        assert!(!PlatformExprStrategy::should_block_partial_exit_residual_slot(1.0, false));
+    }
+
     #[test]
     fn platform_aiquant_daily_top_up_uses_remaining_slot_budget() {
         let prev_date = d(2025, 2, 2);