feat(editor): capture_pie_movement_clip include_ui — composited game+UI frames

Source/MonolithEditor/Private/MonolithEditorActions.cpp

@@ -610,6 +610,7 @@ void FMonolithEditorActions::RegisterActions(FMonolithLogCapture* LogCapture)
 			.Optional(TEXT("marker"), TEXT("string"), TEXT("Log marker token. Default MONOLITH_CLIP."), TEXT("MONOLITH_CLIP"))
 			.Optional(TEXT("duration"), TEXT("number"), TEXT("Seconds the editor loop advances PIE before the session auto-completes (clamped 0-120). Default 5."), TEXT("5"))
 			.Optional(TEXT("capture_interval"), TEXT("number"), TEXT("Seconds between captured frames (clamped 0.05-5). Default 0.25."), TEXT("0.25"))
+			.Optional(TEXT("include_ui"), TEXT("boolean"), TEXT("Capture the composited backbuffer (game + UMG/Slate UI) via the engine screenshot path — the `shot showui` mechanism — instead of the scene-only viewport read. Frames land at end-of-frame (async), so per-frame uniformity validation is skipped. With PIE docked in the editor the backbuffer includes editor chrome; use new-window PIE for a clean game+UI clip. Default false."), TEXT("false"))
 			.Optional(TEXT("sample_vars"), TEXT("array"), TEXT("AnimInstance variable names sampled each frame. Default [GroundSpeed, bShouldMove, DesiredYawDelta]."))
 			.Optional(TEXT("pawn_class"), TEXT("string"), TEXT("Substring of the target pawn's class name to sample. Omit to use the first player controller's pawn."))
 			.Optional(TEXT("console_script"), TEXT("array"), TEXT("Console commands run on the PIE world at start (drive the movement)."))
@@ -6264,6 +6265,8 @@ FMonolithActionResult FMonolithEditorActions::HandleCapturePieMovementClip(const
 	Session.bCaptureFrames = true;
 	Session.CaptureInterval = Interval;
 	Session.OutputDir = OutputDir;
+	Params->TryGetBoolField(TEXT("include_ui"), Session.bIncludeUi);
+	const bool bIncludeUi = Session.bIncludeUi;
 
 	const FString SessionId = FPieSmokeSessionManager::Get().CreateSession(MoveTemp(Session));
 
@@ -6276,6 +6279,7 @@ FMonolithActionResult FMonolithEditorActions::HandleCapturePieMovementClip(const
 	Result->SetStringField(TEXT("resolved_output_dir"), OutputDir);   // explicit alias for callers
 	Result->SetNumberField(TEXT("duration"), Duration);
 	Result->SetNumberField(TEXT("capture_interval"), Interval);
+	Result->SetBoolField(TEXT("include_ui"), bIncludeUi);
 	return FMonolithActionResult::Success(Result);
 }
 

Source/MonolithEditor/Private/MonolithPieSmokeSession.cpp

@@ -1290,6 +1290,28 @@ void FPieSmokeSessionManager::AdvanceSession(FPieSmokeSession& Session)
 
 			const FString FramePath = Session.OutputDir /
 				FString::Printf(TEXT("frame_%03d.png"), Session.CaptureFrameIndex);
+
+			// include_ui: ride the engine screenshot path (the `shot showui`
+			// mechanism) — Slate composites the full backbuffer (game + UMG)
+			// and writes the file at END OF FRAME. Asynchronous by nature:
+			// bSaved/uniformity can't be verified here, so these frames count
+			// as requested-valid and the clip directory holds the truth.
+			if (Session.bIncludeUi)
+			{
+				IFileManager::Get().MakeDirectory(*Session.OutputDir, true);
+				FScreenshotRequest::RequestScreenshot(FramePath, /*bShowUI*/true, /*bAddFilenameSuffix*/false);
+				Sample.FramePath = FramePath;
+				Sample.bFrameUniform = false;
+				Sample.bFrameValid = true;
+				if (Session.CaptureFrameIndex >= Session.DiscardFirstFrames)
+				{
+					++Session.ValidFrames;
+				}
+				Session.LastCaptureSeconds = SampleTime;
+				++Session.CaptureFrameIndex;
+			}
+			else
+			{
 			// #7 flush the render thread before the very first ReadPixels so a warm-up /
 			// uniform first frame is not produced in the first place.
 			const bool bFirstCapture = (Session.CaptureFrameIndex == 0);
@@ -1320,6 +1342,7 @@ void FPieSmokeSessionManager::AdvanceSession(FPieSmokeSession& Session)
 					TEXT("capture_pie_movement_clip: PIE viewport unavailable for session %s — capture deferred."),
 					*Session.Id);
 			}
+			} // !bIncludeUi (scene-only ReadPixels path)
 		}
 	}
 

Source/MonolithEditor/Private/MonolithPieSmokeSession.h

@@ -297,6 +297,13 @@ struct FPieSmokeSession
 	FString OutputDir;
 	int32 CaptureFrameIndex = 0;
 	bool bCaptureDeferred = false;    // set if viewport capture is unavailable in this build path
+	/** Capture the composited backbuffer (game + UMG/Slate UI) via the engine
+	 *  screenshot path — the `shot showui` mechanism — instead of the raw
+	 *  scene-only viewport read. Async (file lands at end of frame), so
+	 *  uniform-frame validity checks don't apply to these frames. NOTE: with
+	 *  PIE docked in the editor the backbuffer is the whole editor window;
+	 *  use new-window PIE for a clean game-plus-UI clip. */
+	bool bIncludeUi = false;
 
 	// #7 first-frame warm-up policy. The first DiscardFirstFrames captured frames are saved to
 	// disk (so the clip is complete) but are NOT counted toward ValidFrames / InvalidFrames —