Fix: Resolve absolute path for uvx to support Claude Desktop on macOS

Claude Desktop on macOS does not inherit the user's full PATH, causing 'spawn uvx ENOENT' errors when it tries to run the server.

This change adds auto-discovery logic to find 'uvx' in common locations (like ~/.local/bin, ~/.cargo/bin, /opt/homebrew/bin) and writes the absolute path to the config.

Also updated README with troubleshooting steps.

Author: dsarno

MCPForUnity/Editor/Helpers/ExecPath.cs

@@ -132,6 +132,56 @@ private static string ResolveClaudeFromNvm(string home)
             catch { return null; }
         }
 
+        // Resolve uvx absolute path. Pref -> env -> common locations -> PATH.
+        internal static string ResolveUvx()
+        {
+            try
+            {
+                if (RuntimeInformation.IsOSPlatform(OSPlatform.OSX) || RuntimeInformation.IsOSPlatform(OSPlatform.Linux))
+                {
+                    string home = Environment.GetFolderPath(Environment.SpecialFolder.UserProfile) ?? string.Empty;
+                    string[] candidates =
+                    {
+                        Path.Combine(home, ".local", "bin", "uvx"),
+                        Path.Combine(home, ".cargo", "bin", "uvx"),
+                        "/usr/local/bin/uvx",
+                        "/opt/homebrew/bin/uvx",
+                        "/usr/bin/uvx"
+                    };
+                    foreach (string c in candidates) { if (File.Exists(c)) return c; }
+
+#if UNITY_EDITOR_OSX || UNITY_EDITOR_LINUX
+                    return Which("uvx", "/opt/homebrew/bin:/usr/local/bin:/usr/bin:/bin");
+#else
+                    return null;
+#endif
+                }
+
+                if (RuntimeInformation.IsOSPlatform(OSPlatform.Windows))
+                {
+#if UNITY_EDITOR_WIN
+                    string userProfile = Environment.GetFolderPath(Environment.SpecialFolder.UserProfile);
+                    string localAppData = Environment.GetFolderPath(Environment.SpecialFolder.LocalApplicationData);
+                    
+                    string[] candidates =
+                    {
+                        Path.Combine(userProfile, ".cargo", "bin", "uvx.exe"),
+                        Path.Combine(localAppData, "uv", "uvx.exe"),
+                        Path.Combine(userProfile, "uv", "uvx.exe"),
+                    };
+                    foreach (string c in candidates) { if (File.Exists(c)) return c; }
+                    
+                    string fromWhere = Where("uvx.exe") ?? Where("uvx");
+                    if (!string.IsNullOrEmpty(fromWhere)) return fromWhere;
+#endif
+                    return null;
+                }
+            }
+            catch { }
+
+            return null;
+        }
+
         // Explicitly set the Claude CLI absolute path override in EditorPrefs
         internal static void SetClaudeCliPath(string absolutePath)
         {

MCPForUnity/Editor/Services/PathResolverService.cs

@@ -34,6 +34,13 @@ public string GetUvxPath()
                 McpLog.Debug("No uvx path override found, falling back to default command");
             }
 
+            // Auto-discovery of absolute path
+            string discovered = ExecPath.ResolveUvx();
+            if (!string.IsNullOrEmpty(discovered))
+            {
+                return discovered;
+            }
+
             return "uvx";
         }
 

MCPForUnity/README.md

@@ -82,6 +82,10 @@ Notes:
   - Help: [Fix MCP for Unity with Cursor, VS Code & Windsurf](https://github.com/CoplayDev/unity-mcp/wiki/1.-Fix-Unity-MCP-and-Cursor,-VSCode-&-Windsurf)
 - Claude CLI not found:
   - Help: [Fix MCP for Unity with Claude Code](https://github.com/CoplayDev/unity-mcp/wiki/2.-Fix-Unity-MCP-and-Claude-Code)
+- Claude Desktop "spawn uvx ENOENT" error on macOS:
+  - Claude Desktop may not inherit your shell's PATH.
+  - The MCP for Unity plugin attempts to automatically resolve the absolute path to `uvx`.
+  - If this fails, use the "Choose UV Install Location" button in the MCP for Unity window to select your `uvx` executable (typically `~/.local/bin/uvx`), or manually update your Claude Desktop config to use the absolute path to `uvx`.
 
 ---