refactor: drop defensive scaffolding made obsolete by module dep declarations (#1122)

Since #1122 declared the Physics 2D, Screen Capture, Image Conversion, etc.
built-in modules as required deps in package.json, Unity Package Manager now
keeps them enabled while MCP for Unity is installed. Two defensive layers
that protected against the now-impossible "module disabled" case become dead
code, plus one sub-floor preprocessor gate that was always-true on our
declared `unity: 2021.3` floor.

Tier 1A — UnityPhysicsCompat.cs
- Revert `Type.GetType("UnityEngine.Physics2D, UnityEngine.Physics2DModule")`
  to `typeof(Physics2D)`. The property-level reflection (for `autoSyncTransforms`
  deprecation in Unity 6.x) stays — that's a different concern.

Tier 1B — TrailControl.cs
- Strip `#if UNITY_2021_1_OR_NEWER` gate. Package floor is 2021.3 per
  package.json, so the `#else` branch ("AddPosition requires Unity 2021.1+")
  is unreachable.

Tier 2 — ScreenshotUtility.cs + callers
- Remove `IsScreenCaptureModuleAvailable` property, `ScreenCaptureModuleNotAvailableError`
  constant, `InvokeCaptureScreenshotAsTexture` helper, and the
  `s_captureScreenshotMethod` / `s_captureScreenshotAsTextureMethod` /
  `s_screenCaptureModuleAvailable` reflection caches.
- Replace reflective `MethodInfo.Invoke` calls with direct `ScreenCapture.X`
  calls in `CaptureToProjectFolder`, `CaptureComposited`, and the
  `ScreenshotCapturer` MonoBehaviour.
- Camera-based fallback path (`FindAvailableCamera` + `CaptureFromCameraToProjectFolder`)
  is preserved — it still handles transient null returns from `ScreenCapture`
  inside `CaptureComposited`.
- Drop pre-flight `if (!IsScreenCaptureModuleAvailable)` gates in
  `ManageUI.cs` (UI render) and `ManageScene.cs` (screenshot path).
- `ProjectInfo` resource: `screenCapture` field is now an invariant `true`
  (preserves API shape for `mcpforunity://project/info` consumers).

Net: 144 lines removed, 15 added. No new tests — the changes are pure
removal of code paths that cannot fire with the current deps declared.

Related: #1160, #1122.

Author: Scriptwonder

MCPForUnity/Editor/Resources/Project/ProjectInfo.cs

@@ -38,7 +38,7 @@ public static object HandleCommand(JObject @params)
                         textmeshpro = IsPackageInstalled("com.unity.textmeshpro"),
                         inputsystem = IsPackageInstalled("com.unity.inputsystem"),
                         uiToolkit = true,
-                        screenCapture = MCPForUnity.Runtime.Helpers.ScreenshotUtility.IsScreenCaptureModuleAvailable,
+                        screenCapture = true,
                     }
                 };
 

MCPForUnity/Editor/Tools/ManageScene.cs

@@ -678,24 +678,9 @@ private static object CaptureScreenshot(SceneCommand cmd)
                     return new SuccessResponse(message, BuildScreenshotResponseData(result, targetCamera.name, includeImage));
                 }
 
-                // Default path: use ScreenCapture API if available, camera fallback otherwise
-                bool screenCaptureAvailable = ScreenshotUtility.IsScreenCaptureModuleAvailable;
+                // Default path: ScreenCapture API for 2022.1+, camera fallback required on older versions.
+#if !UNITY_2022_1_OR_NEWER
                 bool hasCameraFallback = Camera.main != null || UnityFindObjectsCompat.FindAll<Camera>().Length > 0;
-
-#if UNITY_2022_1_OR_NEWER
-                if (!screenCaptureAvailable && !hasCameraFallback)
-                {
-                    return new ErrorResponse(
-                        "Cannot capture screenshot. The Screen Capture module is not enabled and no Camera was found in the scene. " +
-                        "Please either: (1) Enable the Screen Capture module: Window > Package Manager > Built-in > Screen Capture > Enable, " +
-                        "or (2) Add a Camera to your scene for camera-based fallback capture."
-                    );
-                }
-                if (!screenCaptureAvailable)
-                {
-                    McpLog.Warn("[ManageScene] Screen Capture module not enabled. Using camera-based fallback.");
-                }
-#else
                 if (!hasCameraFallback)
                 {
                     return new ErrorResponse(

MCPForUnity/Editor/Tools/ManageUI.cs

@@ -927,12 +927,6 @@ private static object RenderUI(JObject @params)
                 }
 
                 // ── Case 2: start a new capture ───────────────────────────────────
-                // Verify the ScreenCapture module is enabled before attempting capture.
-                if (!ScreenshotUtility.IsScreenCaptureModuleAvailable)
-                {
-                    return new ErrorResponse(ScreenshotUtility.ScreenCaptureModuleNotAvailableError);
-                }
-
                 // Only one capture in flight at a time.  If one is already pending,
                 // reject rather than silently overwriting the state.
                 if (s_pendingCaptureStarted)

MCPForUnity/Editor/Tools/Vfx/TrailControl.cs

@@ -24,13 +24,9 @@ public static object Emit(JObject @params)
 
             RendererHelpers.EnsureMaterial(tr);
 
-#if UNITY_2021_1_OR_NEWER
             Vector3 pos = ManageVfxCommon.ParseVector3(@params["position"]);
             tr.AddPosition(pos);
             return new { success = true, message = $"Emitted at ({pos.x}, {pos.y}, {pos.z})" };
-#else
-            return new { success = false, message = "AddPosition requires Unity 2021.1+" };
-#endif
         }
     }
 }

MCPForUnity/Runtime/Helpers/ScreenshotUtility.cs

@@ -50,57 +50,6 @@ public static class ScreenshotUtility
         /// or globally via <c>ScreenshotPreferences</c> in the Editor assembly.
         /// </summary>
         public const string DefaultFolder = "Assets/Screenshots";
-        private static bool s_loggedLegacyScreenCaptureFallback;
-        private static bool? s_screenCaptureModuleAvailable;
-        private static System.Reflection.MethodInfo s_captureScreenshotMethod;
-        private static System.Reflection.MethodInfo s_captureScreenshotAsTextureMethod;
-
-        /// <summary>
-        /// Checks if the Screen Capture module (com.unity.modules.screencapture) is enabled.
-        /// This module can be disabled in Package Manager > Built-in, which removes the ScreenCapture class.
-        /// </summary>
-        public static bool IsScreenCaptureModuleAvailable
-        {
-            get
-            {
-                if (!s_screenCaptureModuleAvailable.HasValue)
-                {
-                    // Check if ScreenCapture type exists (module might be disabled in Package Manager > Built-in)
-                    var screenCaptureType = Type.GetType("UnityEngine.ScreenCapture, UnityEngine.ScreenCaptureModule")
-                        ?? Type.GetType("UnityEngine.ScreenCapture, UnityEngine.CoreModule");
-                    s_screenCaptureModuleAvailable = screenCaptureType != null;
-                    if (screenCaptureType != null)
-                    {
-                        s_captureScreenshotMethod = screenCaptureType.GetMethod("CaptureScreenshot",
-                            new Type[] { typeof(string), typeof(int) });
-                        s_captureScreenshotAsTextureMethod = screenCaptureType.GetMethod("CaptureScreenshotAsTexture",
-                            new Type[] { typeof(int) });
-                    }
-                }
-                return s_screenCaptureModuleAvailable.Value;
-            }
-        }
-
-        /// <summary>
-        /// Reflective invocation of ScreenCapture.CaptureScreenshotAsTexture(int). Returns
-        /// null when the Screen Capture module is disabled. Centralised so the only direct
-        /// reference to ScreenCapture lives here.
-        /// </summary>
-        internal static Texture2D InvokeCaptureScreenshotAsTexture(int superSize)
-        {
-            if (!IsScreenCaptureModuleAvailable || s_captureScreenshotAsTextureMethod == null)
-                return null;
-            return s_captureScreenshotAsTextureMethod.Invoke(null, new object[] { superSize }) as Texture2D;
-        }
-
-        /// <summary>
-        /// Error message to display when Screen Capture module is not available.
-        /// </summary>
-        public const string ScreenCaptureModuleNotAvailableError =
-            "The Screen Capture module (com.unity.modules.screencapture) is not enabled. " +
-            "To use screenshot capture with ScreenCapture API, please enable it in Unity: " +
-            "Window > Package Manager > Built-in > Screen Capture > Enable. " +
-            "Alternatively, MCP for Unity will use camera-based capture as a fallback if a Camera exists in the scene.";
 
         private static Camera FindAvailableCamera()
         {
@@ -127,44 +76,10 @@ public static ScreenshotCaptureResult CaptureToProjectFolder(
             bool ensureUniqueFileName = true,
             string folderOverride = null)
         {
-            // Use reflection to call ScreenCapture.CaptureScreenshot so the code compiles
-            // even when the Screen Capture module (com.unity.modules.screencapture) is disabled.
-            if (IsScreenCaptureModuleAvailable && s_captureScreenshotMethod != null)
-            {
-                ScreenshotCaptureResult result = PrepareCaptureResult(fileName, superSize, ensureUniqueFileName, folderOverride, isAsync: true);
-                // ScreenCapture.CaptureScreenshot accepts paths relative to the project root.
-                s_captureScreenshotMethod.Invoke(null, new object[] { result.ProjectRelativePath, result.SuperSize });
-                return result;
-            }
-            else
-            {
-                // Module disabled or unavailable - try camera fallback
-                Debug.LogWarning("[MCP for Unity] " + ScreenCaptureModuleNotAvailableError);
-                return CaptureWithCameraFallback(fileName, superSize, ensureUniqueFileName, folderOverride);
-            }
-        }
-
-        private static ScreenshotCaptureResult CaptureWithCameraFallback(string fileName, int superSize, bool ensureUniqueFileName, string folderOverride)
-        {
-            if (!s_loggedLegacyScreenCaptureFallback)
-            {
-                Debug.Log("[MCP for Unity] Using camera-based screenshot capture. " +
-                    "This requires a Camera in the scene. For best results on Unity 2022.1+, ensure the Screen Capture module is enabled: " +
-                    "Window > Package Manager > Built-in > Screen Capture > Enable.");
-                s_loggedLegacyScreenCaptureFallback = true;
-            }
-
-            var cam = FindAvailableCamera();
-            if (cam == null)
-            {
-                throw new InvalidOperationException(
-                    "No camera found to capture screenshot. Camera-based capture requires a Camera in the scene. " +
-                    "Either add a Camera to your scene, or enable the Screen Capture module: " +
-                    "Window > Package Manager > Built-in > Screen Capture > Enable."
-                );
-            }
-
-            return CaptureFromCameraToProjectFolder(cam, fileName, superSize, ensureUniqueFileName, folderOverride: folderOverride);
+            ScreenshotCaptureResult result = PrepareCaptureResult(fileName, superSize, ensureUniqueFileName, folderOverride, isAsync: true);
+            // ScreenCapture.CaptureScreenshot accepts paths relative to the project root.
+            ScreenCapture.CaptureScreenshot(result.ProjectRelativePath, result.SuperSize);
+            return result;
         }
 
         /// <summary>
@@ -283,7 +198,7 @@ private static Texture2D CaptureCompositedAfterFrame(int superSize, int timeoutS
         /// <summary>
         /// Captures a screenshot using ScreenCapture.CaptureScreenshotAsTexture, which captures the
         /// final composited frame including UI Toolkit overlays, post-processing, etc.
-        /// Falls back to camera-based capture if ScreenCapture is unavailable.
+        /// Falls back to camera-based capture if ScreenCapture returns null at runtime.
         /// </summary>
         public static ScreenshotCaptureResult CaptureComposited(
             string fileName = null,
@@ -293,16 +208,6 @@ public static ScreenshotCaptureResult CaptureComposited(
             int maxResolution = 0,
             string folderOverride = null)
         {
-            if (!IsScreenCaptureModuleAvailable || s_captureScreenshotAsTextureMethod == null)
-            {
-                var fallbackCamera = FindAvailableCamera();
-                if (fallbackCamera != null)
-                    return CaptureFromCameraToProjectFolder(fallbackCamera, fileName, superSize, ensureUniqueFileName,
-                        includeImage, maxResolution, folderOverride: folderOverride);
-
-                throw new InvalidOperationException("ScreenCapture module is unavailable and no fallback camera found.");
-            }
-
             ScreenshotCaptureResult result = PrepareCaptureResult(fileName, superSize, ensureUniqueFileName, folderOverride: folderOverride, isAsync: false);
             Texture2D tex = null;
             Texture2D downscaled = null;
@@ -315,9 +220,9 @@ public static ScreenshotCaptureResult CaptureComposited(
                 // composited; route through WaitForEndOfFrame instead.
                 tex = Application.isPlaying
                     ? CaptureCompositedAfterFrame(result.SuperSize)
-                    : InvokeCaptureScreenshotAsTexture(result.SuperSize);
+                    : ScreenCapture.CaptureScreenshotAsTexture(result.SuperSize);
 #else
-                tex = InvokeCaptureScreenshotAsTexture(result.SuperSize);
+                tex = ScreenCapture.CaptureScreenshotAsTexture(result.SuperSize);
 #endif
                 if (tex == null)
                 {
@@ -857,7 +762,7 @@ private System.Collections.IEnumerator Start()
         {
             yield return new WaitForEndOfFrame();
             Texture2D tex = null;
-            try { tex = ScreenshotUtility.InvokeCaptureScreenshotAsTexture(_superSize); }
+            try { tex = ScreenCapture.CaptureScreenshotAsTexture(_superSize); }
             catch (Exception ex) { Debug.LogError($"[MCP for Unity] CaptureScreenshotAsTexture failed: {ex.Message}"); }
             _onComplete?.Invoke(tex);
             Destroy(gameObject);

MCPForUnity/Runtime/Helpers/UnityPhysicsCompat.cs

@@ -17,15 +17,10 @@ namespace MCPForUnity.Runtime.Helpers
     ///
     /// We use reflection rather than direct property access so calls stay clean of
     /// CS0618 warnings AND survive eventual removal of the obsolete property without
-    /// a recompile of this package. Type lookups go through <see cref="Type.GetType(string)"/>
-    /// so this file compiles even when the Physics 2D built-in module is disabled in
-    /// the Package Manager.
+    /// a recompile of this package.
     /// </summary>
     public static class UnityPhysicsCompat
     {
-        // Assembly-qualified name — resolved at runtime so the file compiles when the
-        // Physics 2D built-in module is disabled in the Package Manager.
-        private const string Physics2DTypeName = "UnityEngine.Physics2D, UnityEngine.Physics2DModule";
         /// <summary>
         /// Cross-version description of the 3D physics simulation mode.
         /// On 2022.2+ this maps onto <c>UnityEngine.SimulationMode</c>; on older
@@ -51,13 +46,9 @@ private static PropertyInfo Physics2DAutoSyncProp
                 if (!_physics2DProbed)
                 {
                     _physics2DProbed = true;
-                    var physics2DType = Type.GetType(Physics2DTypeName);
-                    if (physics2DType != null)
-                    {
-                        _physics2DAutoSync = physics2DType.GetProperty(
-                            "autoSyncTransforms",
-                            BindingFlags.Public | BindingFlags.Static);
-                    }
+                    _physics2DAutoSync = typeof(Physics2D).GetProperty(
+                        "autoSyncTransforms",
+                        BindingFlags.Public | BindingFlags.Static);
                 }
                 return _physics2DAutoSync;
             }