diff --git a/Assets/Editor/PuzzleChainEditorWindow.cs b/Assets/Editor/PuzzleChainEditorWindow.cs
index cfbe5467..708dc14b 100644
--- a/Assets/Editor/PuzzleChainEditorWindow.cs
+++ b/Assets/Editor/PuzzleChainEditorWindow.cs
@@ -27,18 +27,38 @@ public class PuzzleChainEditorWindow : EditorWindow
     private void LoadPuzzleSteps()
     {
         puzzleSteps.Clear();
-        string[] guids = AssetDatabase.FindAssets("t:PuzzleStepSO", new[] { "Assets/Data/Puzzles" });
+        // Find all PuzzleStepSO assets in the project
+        string[] guids = AssetDatabase.FindAssets("t:PuzzleStepSO");
         foreach (var guid in guids)
         {
             var path = AssetDatabase.GUIDToAssetPath(guid);
-            var step = AssetDatabase.LoadAssetAtPath<PuzzleStepSO>(path);
-            if (step != null)
-                puzzleSteps.Add(step);
+            // Only include those under Assets/Data/Puzzles (case-insensitive)
+            if (path.Replace('\\', '/').StartsWith("Assets/Data/Puzzles", System.StringComparison.OrdinalIgnoreCase))
+            {
+                var step = AssetDatabase.LoadAssetAtPath<PuzzleStepSO>(path);
+                if (step != null)
+                    puzzleSteps.Add(step);
+            }
+        }
+        // Remove any nulls just in case
+        puzzleSteps.RemoveAll(s => s == null);
+        // Remove nulls from unlocks lists
+        foreach (var step in puzzleSteps)
+        {
+            if (step.unlocks != null)
+                step.unlocks.RemoveAll(u => u == null);
         }
     }
 
     private void ProcessPuzzleChains()
     {
+        // Defensive: ensure no nulls in puzzleSteps or unlocks
+        puzzleSteps.RemoveAll(s => s == null);
+        foreach (var step in puzzleSteps)
+        {
+            if (step.unlocks != null)
+                step.unlocks.RemoveAll(u => u == null);
+        }
         dependencyGraph = PuzzleGraphUtility.BuildDependencyGraph(puzzleSteps);
     }
 
@@ -51,9 +71,10 @@ public class PuzzleChainEditorWindow : EditorWindow
             return;
         }
         scrollPos = EditorGUILayout.BeginScrollView(scrollPos);
-        var initialSteps = PuzzleGraphUtility.FindInitialSteps(dependencyGraph);
+        var initialSteps = dependencyGraph != null ? PuzzleGraphUtility.FindInitialSteps(dependencyGraph) : new List<PuzzleStepSO>();
         foreach (var step in initialSteps)
         {
+            if (step == null) continue; // Defensive
             EditorGUILayout.BeginVertical("box");
             EditorGUILayout.LabelField($"Step Path: {step.displayName} ({step.stepId})", EditorStyles.largeLabel);
             GUILayout.Space(6);
@@ -66,6 +87,10 @@ public class PuzzleChainEditorWindow : EditorWindow
 
     private void DrawStepTree(PuzzleStepSO step, int indent)
     {
+        if (step == null) {
+            EditorGUILayout.LabelField("[Missing Step]", EditorStyles.boldLabel);
+            return;
+        }
         EditorGUILayout.BeginHorizontal();
         GUILayout.Space(indent * INDENT_SIZE);
         EditorGUILayout.BeginVertical("box");
@@ -74,15 +99,18 @@ public class PuzzleChainEditorWindow : EditorWindow
         GUILayout.Space(4);
         if (GUILayout.Button("Open in Inspector", GUILayout.Width(150)))
         {
-            Selection.activeObject = step; // Opens in Inspector
-            EditorGUIUtility.PingObject(step); // Highlights in Project
+            Selection.activeObject = step;
+            EditorGUIUtility.PingObject(step);
         }
         EditorGUILayout.EndVertical();
         EditorGUILayout.EndHorizontal();
-        GUILayout.Space(6); // Spacer between steps
-        foreach (var unlock in step.unlocks)
+        GUILayout.Space(6);
+        if (step.unlocks != null)
         {
-            DrawStepTree(unlock, indent + 1);
+            foreach (var unlock in step.unlocks)
+            {
+                DrawStepTree(unlock, indent + 1);
+            }
         }
     }
 }