fix(gameplay): address Codex PR review — snapshot scoring inputs, fix undo net restoration

- StageManager: capture totalCost/boardArea/traceCount before async simulation
  to prevent race condition with live board edits during simulation
- RouteTraceCommand: fix Undo for probe nets that have no traces — restore
  previous net connection even when RemoveTrace auto-deletes the net

Author: okenic03-code

Assets/10_Scripts/10_Runtime/40_Managers/StageManager.cs

@@ -203,6 +203,22 @@ private async UniTaskVoid RunSimulationAndEvaluateAsync(CancellationToken cancel
                     }
                 }
 
+                // Snapshot scoring inputs before awaiting simulation to avoid race with live board edits.
+                float totalCost = 0f;
+                foreach (var component in boardState.Components)
+                {
+                    if (component.IsFixed) continue;
+                    var def = _simulationManager.GetComponentDefinition(component.ComponentDefinitionId);
+                    if (def != null)
+                    {
+                        totalCost += def.BaseCost;
+                    }
+                }
+
+                var contentBounds = boardState.ComputeContentBounds();
+                int boardArea = Math.Max(1, contentBounds.Width * contentBounds.Height);
+                int traceCount = boardState.Traces.Count;
+
                 cancellationToken.ThrowIfCancellationRequested();
                 await _simulationManager.RunSimulationAsync(boardState, probes, true, true, cancellationToken);
                 cancellationToken.ThrowIfCancellationRequested();
@@ -226,22 +242,7 @@ private async UniTaskVoid RunSimulationAndEvaluateAsync(CancellationToken cancel
                     evalResult = _objectiveEvaluator.Evaluate(simResult, testCaseInputs.ToArray());
                 }
 
-                // Calculate total component cost by summing BaseCost of each placed component
-                float totalCost = 0f;
-                foreach (var component in boardState.Components)
-                {
-                    // Exclude fixed (pre-placed) components from budget calculation
-                    if (component.IsFixed) continue;
-                    var def = _simulationManager.GetComponentDefinition(component.ComponentDefinitionId);
-                    if (def != null)
-                    {
-                        totalCost += def.BaseCost;
-                    }
-                }
-
                 // Build scoring input from evaluation + board size + stage target.
-                var contentBounds = _gameManager.BoardState.ComputeContentBounds();
-                int boardArea = Math.Max(1, contentBounds.Width * contentBounds.Height);
                 int targetArea = _currentStage.TargetArea;
 
                 var scoringInput = new ScoringInput(
@@ -250,7 +251,7 @@ private async UniTaskVoid RunSimulationAndEvaluateAsync(CancellationToken cancel
                     budgetLimit: _currentStage.BudgetLimit,
                     boardArea: boardArea,
                     targetArea: targetArea,
-                    traceCount: boardState.Traces.Count
+                    traceCount: traceCount
                 );
 
                 // Calculate final score breakdown

Assets/10_Scripts/10_Runtime/85_Commands/RouteTraceCommand.cs

@@ -22,6 +22,8 @@ public class RouteTraceCommand : ICommand
 
         // State captured during Execute for Undo
         private int _netId;
+        private string _netName;
+        private int? _restoredRouteNetId;
         private readonly List<int> _addedSegmentIds = new List<int>();
         // ReSharper disable once NotAccessedField.Local
         private bool _createdNewNet;
@@ -64,9 +66,11 @@ public void Execute()
 
             _addedSegmentIds.Clear();
             _didMerge = false;
+            _restoredRouteNetId = null;
 
             // Resolve which net to use (may create a new one)
             _netId = ResolveNetId();
+            _netName = _boardState.GetNet(_netId)?.NetName;
 
             // Connect pins to the net
             _boardState.ConnectPinToNet(_netId, _startPin);
@@ -281,15 +285,27 @@ private void DisconnectPinFromNet(PinReference pinRef, Net net)
 
         private void RestorePreviousPinConnection(PinReference pinRef, int? previousNetId)
         {
-            if (!previousNetId.HasValue || previousNetId.Value == _netId)
+            if (!previousNetId.HasValue)
                 return;
 
-            // Only restore if the previous net still exists
-            var previousNet = _boardState.GetNet(previousNetId.Value);
+            int targetNetId = previousNetId.Value;
+            if (_restoredRouteNetId.HasValue && previousNetId.Value == _netId)
+            {
+                targetNetId = _restoredRouteNetId.Value;
+            }
+
+            var previousNet = _boardState.GetNet(targetNetId);
             if (previousNet == null)
-                return;
+            {
+                if (previousNetId.Value != _netId || string.IsNullOrEmpty(_netName))
+                    return;
+
+                previousNet = _boardState.CreateNet(_netName);
+                _restoredRouteNetId = previousNet.NetId;
+                targetNetId = previousNet.NetId;
+            }
 
-            _boardState.ConnectPinToNet(previousNetId.Value, pinRef);
+            _boardState.ConnectPinToNet(targetNetId, pinRef);
         }
     }
 }