fix: address CodeRabbit feedback on resource leaks and shader safety

- Fix material creation to handle missing shaders (URP/HDRP fallbacks)
- Add try/finally blocks for RenderTexture resource management
- Fix Python closure variable binding (ruff B023)

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <[email protected]>

Author: dsarno

UnityMcpBridge/Editor/Tools/ManageAsset.cs

@@ -179,8 +179,18 @@ private static object CreateAsset(JObject @params)
                 }
                 else if (lowerAssetType == "material")
                 {
-                    Material mat = new Material(Shader.Find("Standard")); // Default shader
-                    // TODO: Apply properties from JObject (e.g., shader name, color, texture assignments)
+                    // Prefer provided shader; fall back to common pipelines
+                    var requested = properties?["shader"]?.ToString();
+                    Shader shader =
+                        (!string.IsNullOrEmpty(requested) ? Shader.Find(requested) : null)
+                        ?? Shader.Find("Universal Render Pipeline/Lit")
+                        ?? Shader.Find("HDRP/Lit")
+                        ?? Shader.Find("Standard")
+                        ?? Shader.Find("Unlit/Color");
+                    if (shader == null)
+                        return Response.Error($"Could not find a suitable shader (requested: '{requested ?? "none"}').");
+
+                    var mat = new Material(shader);
                     if (properties != null)
                         ApplyMaterialProperties(mat, properties);
                     AssetDatabase.CreateAsset(mat, fullPath);
@@ -1261,24 +1271,29 @@ private static object GetAssetData(string path, bool generatePreview = false)
                     {
                         // Ensure texture is readable for EncodeToPNG
                         // Creating a temporary readable copy is safer
-                        RenderTexture rt = RenderTexture.GetTemporary(
-                            preview.width,
-                            preview.height
-                        );
-                        Graphics.Blit(preview, rt);
+                        RenderTexture rt = null;
+                        Texture2D readablePreview = null;
                         RenderTexture previous = RenderTexture.active;
-                        RenderTexture.active = rt;
-                        Texture2D readablePreview = new Texture2D(preview.width, preview.height);
-                        readablePreview.ReadPixels(new Rect(0, 0, rt.width, rt.height), 0, 0);
-                        readablePreview.Apply();
-                        RenderTexture.active = previous;
-                        RenderTexture.ReleaseTemporary(rt);
-
-                        byte[] pngData = readablePreview.EncodeToPNG();
+                        try
+                        {
+                            rt = RenderTexture.GetTemporary(preview.width, preview.height);
+                            Graphics.Blit(preview, rt);
+                            RenderTexture.active = rt;
+                            readablePreview = new Texture2D(preview.width, preview.height);
+                            readablePreview.ReadPixels(new Rect(0, 0, rt.width, rt.height), 0, 0);
+                            readablePreview.Apply();
+                        }
+                        finally
+                        {
+                            RenderTexture.active = previous;
+                            if (rt != null) RenderTexture.ReleaseTemporary(rt);
+                        }
+
+                        var pngData = readablePreview.EncodeToPNG();
                         previewBase64 = Convert.ToBase64String(pngData);
                         previewWidth = readablePreview.width;
                         previewHeight = readablePreview.height;
-                        UnityEngine.Object.DestroyImmediate(readablePreview); // Clean up temp texture
+                        UnityEngine.Object.DestroyImmediate(readablePreview);
                     }
                     catch (Exception ex)
                     {

UnityMcpBridge/UnityMcpServer~/src/tools/manage_script_edits.py

@@ -630,8 +630,8 @@ def line_col_from_index(idx: int) -> Tuple[int, int]:
                         if not m:
                             continue
                         # Expand $1, $2... in replacement using this match
-                        def _expand_dollars(rep: str) -> str:
-                            return _re.sub(r"\$(\d+)", lambda g: m.group(int(g.group(1))) or "", rep)
+                        def _expand_dollars(rep: str, _m=m) -> str:
+                            return _re.sub(r"\$(\d+)", lambda g: _m.group(int(g.group(1))) or "", rep)
                         repl = _expand_dollars(text_field)
                         sl, sc = line_col_from_index(m.start())
                         el, ec = line_col_from_index(m.end())
@@ -767,8 +767,8 @@ def line_col_from_index(idx: int) -> Tuple[int, int]:
                         if not m:
                             continue
                         # Expand $1, $2... backrefs in replacement using the first match (consistent with mixed-path behavior)
-                        def _expand_dollars(rep: str) -> str:
-                            return _re.sub(r"\$(\d+)", lambda g: m.group(int(g.group(1))) or "", rep)
+                        def _expand_dollars(rep: str, _m=m) -> str:
+                            return _re.sub(r"\$(\d+)", lambda g: _m.group(int(g.group(1))) or "", rep)
                         repl_expanded = _expand_dollars(repl)
                         # Let C# side handle validation using Unity's built-in compiler services
                         sl, sc = line_col_from_index(m.start())