From 4b5ae0fecd97e23bc42b9143b1ed6c71dfeb3943 Mon Sep 17 00:00:00 2001
From: Doug Frazier <dougfy@yahoo.com>
Date: Sun, 26 Apr 2026 15:57:01 -0700
Subject: [PATCH] fix: resolve Roslyn assemblies on macOS
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On macOS, EditorApplication.applicationPath points to the Unity.app
bundle itself (e.g. /Applications/Unity/Hub/Editor/2022.3.62f2/Unity.app).
The previous code called Path.GetDirectoryName() on that path and then
appended 'Data/...' — a layout that only exists on Windows and Linux.

On macOS the Roslyn DLLs live inside Unity.app/Contents/..., so
TryLoadRoslyn() never found them and ExecuteCode always returned the
'Roslyn is not available' error.

Fix: detect when applicationPath ends in '.app' and add Unity.app/Contents
as an additional data root alongside the existing Windows/Linux root.
Also adds Tools/ScriptUpdater as a search location (ships Mono-compatible
Roslyn assemblies in all 2022.3.x builds).

Tested on macOS (Unity 2022.3.62f2, Apple Silicon).
---
 Editor/MCPEditorCommands.cs | 45 +++++++++++++++++++++++++++----------
 1 file changed, 33 insertions(+), 12 deletions(-)

diff --git a/Editor/MCPEditorCommands.cs b/Editor/MCPEditorCommands.cs
index 3022d49..562b9d0 100755
--- a/Editor/MCPEditorCommands.cs
+++ b/Editor/MCPEditorCommands.cs
@@ -95,18 +95,39 @@ private static bool TryLoadRoslyn()
             // If not already loaded, try to find and load them from the Unity editor directory
             if (_roslynCSharpAsm == null || _roslynCoreAsm == null)
             {
-                string editorDir = Path.GetDirectoryName(EditorApplication.applicationPath);
-                string managedDir = Path.Combine(editorDir, "Data", "Managed");
-                string toolsDir = Path.Combine(editorDir, "Data", "Tools", "Roslyn");
-                // Mono-compatible Roslyn assemblies (preferred for Unity's Mono runtime)
-                string monoDir = Path.Combine(editorDir, "Data", "MonoBleedingEdge", "lib", "mono", "4.5");
-                string msbuildRoslynDir = Path.Combine(editorDir, "Data", "MonoBleedingEdge", "lib", "mono", "msbuild", "Current", "bin", "Roslyn");
-                // ApiUpdater has full Roslyn assemblies
-                string apiUpdaterDir = Path.Combine(editorDir, "Data", "Tools", "BuildPipeline", "Compilation", "ApiUpdater");
-                // DotNetSdkRoslyn contains .NET Core assemblies — may fail on Mono, tried last
-                string sdkRoslynDir = Path.Combine(editorDir, "Data", "DotNetSdkRoslyn");
-
-                foreach (var searchDir in new[] { managedDir, toolsDir, monoDir, msbuildRoslynDir, apiUpdaterDir, sdkRoslynDir, editorDir })
+                // Resolve the editor's "Data" directory across platforms.
+                // Windows: <EditorDir>/Data/...
+                // macOS:   EditorApplication.applicationPath ends in "Unity.app"; Data lives at Unity.app/Contents
+                // Linux:   <EditorDir>/Data/... (same as Windows)
+                string appPath = EditorApplication.applicationPath;
+                string editorDir = Path.GetDirectoryName(appPath);
+                var dataRoots = new List<string>();
+                // Windows / Linux layout
+                if (!string.IsNullOrEmpty(editorDir))
+                    dataRoots.Add(Path.Combine(editorDir, "Data"));
+                // macOS layout: Unity.app/Contents
+                if (!string.IsNullOrEmpty(appPath) && appPath.EndsWith(".app", StringComparison.OrdinalIgnoreCase))
+                    dataRoots.Add(Path.Combine(appPath, "Contents"));
+
+                var searchDirs = new List<string>();
+                foreach (var data in dataRoots)
+                {
+                    searchDirs.Add(Path.Combine(data, "Managed"));
+                    searchDirs.Add(Path.Combine(data, "Tools", "Roslyn"));
+                    // Mono-compatible Roslyn assemblies (preferred for Unity's Mono runtime)
+                    searchDirs.Add(Path.Combine(data, "MonoBleedingEdge", "lib", "mono", "4.5"));
+                    searchDirs.Add(Path.Combine(data, "MonoBleedingEdge", "lib", "mono", "msbuild", "Current", "bin", "Roslyn"));
+                    // ApiUpdater has full Roslyn assemblies
+                    searchDirs.Add(Path.Combine(data, "Tools", "BuildPipeline", "Compilation", "ApiUpdater"));
+                    // ScriptUpdater also ships Roslyn (Mono-compatible)
+                    searchDirs.Add(Path.Combine(data, "Tools", "ScriptUpdater"));
+                    // DotNetSdkRoslyn contains .NET Core assemblies — may fail on Mono, tried last
+                    searchDirs.Add(Path.Combine(data, "DotNetSdkRoslyn"));
+                }
+                if (!string.IsNullOrEmpty(editorDir))
+                    searchDirs.Add(editorDir);
+
+                foreach (var searchDir in searchDirs)
                 {
                     if (!Directory.Exists(searchDir)) continue;
                     if (_roslynCoreAsm == null)