diff --git a/Disp/MachiningProjectDisplayee.cs b/Disp/MachiningProjectDisplayee.cs
index 8192c7f..e7b449c 100644
--- a/Disp/MachiningProjectDisplayee.cs
+++ b/Disp/MachiningProjectDisplayee.cs
@@ -1,4 +1,4 @@
-using Hi.Coloring;
+using Hi.Coloring;
 using Hi.MachiningProcs;
 using Hi.Common;
 using Hi.Disp;
@@ -8,6 +8,7 @@ using System.Collections.Generic;
 using System.Collections;
 using Hi.Geom;
 using System.Linq;
+using Hi.NcMech.Solids;
 using Hi.Numerical;
 using System;
 
@@ -85,26 +86,28 @@ public class MachiningProjectDisplayee : IDisplayee, IGetAnchor
 
 		LocalProjectService localProjectService = LocalProjectService;
 		HardNcEnv ncEnv = machiningProject.NcEnv;
-		var workpiece = localProjectService.Workpiece;
+		//the execution scene draws the RUNTIME face throughout (equipment
+		//split: the service facades expose the authored setup face instead)
 		var machiningEquipment = localProjectService.MachiningEquipment;
+		var workpiece = machiningEquipment?.Workpiece;
 
 		if (RenderingFlagBitArray[(int)RenderingFlag.ClStrip])
 		{
 			localProjectService.ClStrip.IsKeepingDispAlive = true;
 			dst.Add(new AnchoredDisplayee(
-				localProjectService.MachiningEquipment?.Workpiece?.ProgramZeroAnchor,
+				workpiece?.ProgramZeroAnchor,
 				localProjectService.ClStrip));
 		}
 		if (RenderingFlagBitArray[(int)RenderingFlag.Mech])
 		{
-			if (localProjectService.MachiningEquipment != null)
+			if (machiningEquipment != null)
 			{
-				List<IAnchoredDisplayee> machAncDisplayees = localProjectService
-				?.MachiningEquipment?.GetAnchoredDisplayeeList() ?? [];
+				List<IAnchoredDisplayee> machAncDisplayees =
+					machiningEquipment.GetAnchoredDisplayeeList() ?? [];
 				HashSet<Anchor> exclusiveAnchorSet = new([
-					.. localProjectService.Workpiece?.Asmb.GetDescendantAnchors()??[],
-						.. localProjectService.MachiningTool?.GetAsmb().GetDescendantAnchors()??[],
-						.. localProjectService.Fixture?.Asmb.GetDescendantAnchors()??[],
+					.. workpiece?.Asmb.GetDescendantAnchors()??[],
+						.. machiningEquipment.MachiningTool?.GetAsmb().GetDescendantAnchors()??[],
+						.. machiningEquipment.Fixture?.Asmb.GetDescendantAnchors()??[],
 					]);
 				dst.AddRange(machAncDisplayees.Where(ad =>
 					!exclusiveAnchorSet.Contains(ad.GetAnchor())));
@@ -118,19 +121,17 @@ public class MachiningProjectDisplayee : IDisplayee, IGetAnchor
 		}
 		if (RenderingFlagBitArray[(int)RenderingFlag.Tool])
 		{
-			if (localProjectService.MachiningEquipment != null
-				&& localProjectService.MachiningTool != null)
+			if (machiningEquipment?.MachiningTool != null)
 				dst.Add(new AnchoredDisplayee(
-				localProjectService.MachiningTool?.GetAnchor(),
-				localProjectService.MachiningTool));
+				machiningEquipment.MachiningTool?.GetAnchor(),
+				machiningEquipment.MachiningTool));
 		}
 		if (RenderingFlagBitArray[(int)RenderingFlag.Fixture])
 		{
-			if (localProjectService.MachiningEquipment != null
-				&& localProjectService.Fixture != null)
+			if (machiningEquipment?.Fixture != null)
 				dst.Add(new AnchoredDisplayee(
-				localProjectService.Fixture?.GeomAnchor,
-				localProjectService.Fixture));
+				machiningEquipment.Fixture?.GeomAnchor,
+				machiningEquipment.Fixture));
 		}
 		if (RenderingFlagBitArray[(int)RenderingFlag.ProgramZero])
 		{
@@ -155,14 +156,16 @@ public class MachiningProjectDisplayee : IDisplayee, IGetAnchor
 	internal static Anchor GetRootAnchor(
 	LocalProjectService localProjectService, BitArray renderingFlagBitArray)
 	{
+		//runtime face throughout: this roots the execution scene
+		var machiningEquipment = localProjectService?.MachiningEquipment;
 		if (renderingFlagBitArray[(int)RenderingFlag.Mech])
-			return localProjectService?.MachiningEquipment?.GetAnchor();
+			return machiningEquipment?.GetAnchor();
 		else if (renderingFlagBitArray[(int)RenderingFlag.WorkpieceGeom])
-			return localProjectService.Workpiece?.GetAnchor();
+			return machiningEquipment?.Workpiece?.GetAnchor();
 		else if (renderingFlagBitArray[(int)RenderingFlag.Fixture])
-			return localProjectService.Fixture?.GetAnchor();
+			return machiningEquipment?.Fixture?.GetAnchor();
 		else if (renderingFlagBitArray[(int)RenderingFlag.Tool])
-			return localProjectService.MachiningTool?.GetAnchor();
+			return machiningEquipment?.MachiningTool?.GetAnchor();
 		else
 			return null;
 	}
@@ -222,9 +225,17 @@ public class MachiningProjectDisplayee : IDisplayee, IGetAnchor
 		bind.ModelMatStack.Pop();
 
 		bind.PushColorByRgb(1, 1, 1);
-		LocalProjectService?.MachiningEquipment?.GetAsmb()?.Display(bind,
-				GetAnchor(),
-				GetAnchoredDisplayeeList().ToArray());
+		var machiningEquipment = LocalProjectService?.MachiningEquipment;
+		//Collision red is per-scenario state owned by the execution equipment
+		//(never stored on the shared Solid geometry): scope it to this scene
+		//so the setup topology never paints it.
+		using (CollisionRedScope.Enter(
+			machiningEquipment == null ? null : machiningEquipment.IsCollisionRed))
+		{
+			machiningEquipment?.GetAsmb()?.Display(bind,
+					GetAnchor(),
+					GetAnchoredDisplayeeList().ToArray());
+		}
 		bind.PopColor();
 	}
 	/// <inheritdoc/>
diff --git a/Machining/DemoMillingByCutterLocation.cs b/Machining/DemoMillingByCutterLocation.cs
index 2f39b17..41e98f0 100644
--- a/Machining/DemoMillingByCutterLocation.cs
+++ b/Machining/DemoMillingByCutterLocation.cs
@@ -51,13 +51,19 @@ namespace Sample.Machining
 
 			var projectDisplayee = new MachiningProjectDisplayee(localProjectService);
 			var device = new ClMillingDevice();
-			localProjectService.MachiningEquipment.MachiningChain = device;
+			//authored face (equipment split): the facade setter installs the
+			//chain on SetupEquipment and the runtime face follows by rebuild
+			localProjectService.MachiningChain = device;
 			localProjectService.ClStrip.IsShowDot = true;
 			double resolution_mm = 0.5;
 			var projectDir = Path.GetDirectoryName(projectPath);
-			localProjectService.WorkpieceService.InitGeom = new StlFile(stlFile_CylinderR20, projectDir);
-			localProjectService.WorkpieceService.IdealGeom = new StlFile(stlFile_CylinderR19, projectDir);
+			//author the workpiece on the setup face, then let the runtime
+			//face follow — a runtime-face write would be wiped by the
+			//session-boundary re-materialise
+			localProjectService.Workpiece.InitGeom = new StlFile(stlFile_CylinderR20, projectDir);
+			localProjectService.Workpiece.IdealGeom = new StlFile(stlFile_CylinderR19, projectDir);
 			localProjectService.Workpiece.InitResolution = resolution_mm;
+			localProjectService.NotifySetupEquipmentEdited();
 
 			SessionShell runtimeApi = localProjectService.SessionShell;
 			runtimeApi.SetNcResolutionFixed(9999, 15);