diff --git a/src/app/editor-store.ts b/src/app/editor-store.ts
index e928533f..f4d7d1d5 100644
--- a/src/app/editor-store.ts
+++ b/src/app/editor-store.ts
@@ -2,6 +2,7 @@ import { CommandHistory } from "../commands/command-history";
 import type { CommandContext, EditorCommand } from "../commands/command";
 import {
   areEditorSelectionsEqual,
+  getSelectionDefaultActiveId,
   normalizeSelectionForWhiteboxSelectionMode,
   type EditorSelection
 } from "../core/selection";
@@ -71,6 +72,7 @@ export interface EditorStoreState {
   activeSceneId: string;
   document: SceneDocument;
   selection: EditorSelection;
+  activeSelectionId: string | null;
   whiteboxSelectionMode: WhiteboxSelectionMode;
   whiteboxSnapEnabled: boolean;
   whiteboxSnapStep: number;
@@ -211,6 +213,7 @@ export class EditorStore {
   private document: SceneDocument;
   private commandTargetSceneId: string | null = null;
   private selection: EditorSelection = { kind: "none" };
+  private activeSelectionId: string | null = null;
   private whiteboxSelectionMode: WhiteboxSelectionMode = "object";
   private whiteboxSnapEnabled = true;
   private whiteboxSnapStep = 1;
@@ -251,6 +254,7 @@ export class EditorStore {
     getSelection: () => this.selection,
     setSelection: (selection) => {
       this.selection = selection;
+      this.activeSelectionId = getSelectionDefaultActiveId(selection);
     },
     getToolMode: () => this.toolMode,
     setToolMode: (toolMode) => {
@@ -624,6 +628,7 @@ export class EditorStore {
     }
 
     this.selection = selection;
+    this.activeSelectionId = getSelectionDefaultActiveId(selection);
     this.emit();
   }
 
@@ -644,6 +649,7 @@ export class EditorStore {
       this.selection,
       mode
     );
+    this.activeSelectionId = getSelectionDefaultActiveId(this.selection);
     this.updateActiveSceneEditorPreferences((preferences) => ({
       ...preferences,
       whiteboxSelectionMode: mode
@@ -726,6 +732,7 @@ export class EditorStore {
     this.syncActiveSceneDocument();
     this.commandTargetSceneId = null;
     this.selection = { kind: "none" };
+    this.activeSelectionId = null;
     this.toolMode = "select";
     this.previousEditingToolMode = "select";
     this.viewportTransientState = createDefaultViewportTransientState();
@@ -821,6 +828,7 @@ export class EditorStore {
       activeSceneId: this.projectDocument.activeSceneId,
       document: this.document,
       selection: this.selection,
+      activeSelectionId: this.activeSelectionId,
       whiteboxSelectionMode: this.whiteboxSelectionMode,
       whiteboxSnapEnabled: this.whiteboxSnapEnabled,
       whiteboxSnapStep: this.whiteboxSnapStep,
diff --git a/src/core/transform-session.ts b/src/core/transform-session.ts
index 51d65e62..49a0603a 100644
--- a/src/core/transform-session.ts
+++ b/src/core/transform-session.ts
@@ -1,5 +1,8 @@
 import { createOpaqueId } from "./ids";
-import type { EditorSelection } from "./selection";
+import {
+  resolveSelectionActiveId,
+  type EditorSelection
+} from "./selection";
 import type { WhiteboxSelectionMode } from "./whitebox-selection-mode";
 import type { Vec3 } from "./vector";
 import {
@@ -149,14 +152,38 @@ export interface EntityTransformTarget {
   initialRotation: EntityTransformRotationState;
 }
 
+export interface BrushesTransformTarget {
+  kind: "brushes";
+  activeBrushId: string;
+  initialPivot: Vec3;
+  items: BrushTransformTarget[];
+}
+
+export interface ModelInstancesTransformTarget {
+  kind: "modelInstances";
+  activeModelInstanceId: string;
+  initialPivot: Vec3;
+  items: ModelInstanceTransformTarget[];
+}
+
+export interface EntitiesTransformTarget {
+  kind: "entities";
+  activeEntityId: string;
+  initialPivot: Vec3;
+  items: EntityTransformTarget[];
+}
+
 export type TransformTarget =
   | BrushTransformTarget
+  | BrushesTransformTarget
   | BrushFaceTransformTarget
   | BrushEdgeTransformTarget
   | BrushVertexTransformTarget
   | ModelInstanceTransformTarget
+  | ModelInstancesTransformTarget
   | PathPointTransformTarget
-  | EntityTransformTarget;
+  | EntityTransformTarget
+  | EntitiesTransformTarget;
 
 export interface BrushTransformPreview {
   kind: "brush";
@@ -202,11 +229,53 @@ export interface EntityTransformPreview {
   rotation: EntityTransformRotationState;
 }
 
+export interface BrushTransformPreviewItem {
+  brushId: string;
+  center: Vec3;
+  rotationDegrees: Vec3;
+  size: Vec3;
+  geometry: BrushGeometry;
+}
+
+export interface BrushesTransformPreview {
+  kind: "brushes";
+  pivot: Vec3;
+  items: BrushTransformPreviewItem[];
+}
+
+export interface ModelInstanceTransformPreviewItem {
+  modelInstanceId: string;
+  position: Vec3;
+  rotationDegrees: Vec3;
+  scale: Vec3;
+}
+
+export interface ModelInstancesTransformPreview {
+  kind: "modelInstances";
+  pivot: Vec3;
+  items: ModelInstanceTransformPreviewItem[];
+}
+
+export interface EntityTransformPreviewItem {
+  entityId: string;
+  position: Vec3;
+  rotation: EntityTransformRotationState;
+}
+
+export interface EntitiesTransformPreview {
+  kind: "entities";
+  pivot: Vec3;
+  items: EntityTransformPreviewItem[];
+}
+
 export type TransformPreview =
   | BrushTransformPreview
+  | BrushesTransformPreview
   | ModelInstanceTransformPreview
+  | ModelInstancesTransformPreview
   | PathPointTransformPreview
-  | EntityTransformPreview;
+  | EntityTransformPreview
+  | EntitiesTransformPreview;
 
 export interface ActiveTransformSession {
   kind: "active";