PageScene: route create/delete/lock/visible/paste through HistoryManager

Wires creation, deletion, lock, visibility, and paste through the new
HistoryManager. Mutator-recorded — every external call site keeps
the same signature it had before; recording happens inside the mutator
or its dep callback, so callers don't grow new responsibilities.

Recordings added:
- actions/addObject, addCharacter, addShape: editor.history.recordCreate(obj)
  replaces the legacy add_creation_undostack call.
- editor.deleteObject: snapshots the target before delegating to
  utils.deleteObject so undo can fully reconstruct it.
- SelectionBridge.lockUnlockObject: takes a recordLockChange dep
  callback, records before/after locked state inline. No coupling
  back to HistoryManager from the bridge.
- Outliner.handleToggleVisibility: records visible before/after at the
  call site (hideObject lives on SceneManager which has no history dep).
- SceneManager.paste: now returns the new Object3D so keymap's paste
  handler can record it via editor.history.recordCreate. The legacy
  add_creation_undostack call inside paste is removed.

keymap.ts: undo/redo target editor.history; deleteSelected routes
through editor.deleteObject (so history records); paste captures the
returned object and records.

Transform recording (gizmo drag, panel inputs) and color stay on the
old check_scene_for_updates diff path until follow-up commits. Old
SceneManager undo machinery (undoStack, undo/redo methods,
add_creation_undostack, the diff helpers) is still in place but only
the diff path drives transforms now.

frontend/apps/artcraft/app/src/pages/PageScene/actions/addCharacter.ts

@@ -17,7 +17,7 @@ export async function addCharacter(
 
   obj.userData.isCharacter = true;
 
-  await editor.sceneManager?.add_creation_undostack(obj);
+  editor.history.recordCreate(obj);
 
   usePageSceneStore.getState().addCharacter({
     id: obj.uuid,

frontend/apps/artcraft/app/src/pages/PageScene/actions/addObject.ts

@@ -15,7 +15,7 @@ export async function addObject(
   );
   if (!obj) return undefined;
 
-  await editor.sceneManager?.add_creation_undostack(obj);
+  editor.history.recordCreate(obj);
 
   usePageSceneStore.getState().addObject({
     id: obj.uuid,

frontend/apps/artcraft/app/src/pages/PageScene/actions/addShape.ts

@@ -16,7 +16,7 @@ export async function addShape(
   if (!obj) return undefined;
   obj.name = item.name ?? "shape";
 
-  await editor.sceneManager?.add_creation_undostack(obj);
+  editor.history.recordCreate(obj);
 
   usePageSceneStore.getState().addShape({
     id: obj.uuid,

frontend/apps/artcraft/app/src/pages/PageScene/comps/Outliner/Outliner.tsx

@@ -53,8 +53,10 @@ const OutlinerRow = ({ item }: { item: OutlinerItem }) => {
 
   const handleToggleVisibility = (e: React.MouseEvent) => {
     e.stopPropagation();
+    const before = item.visible;
     usePageSceneStore.getState().toggleOutlinerVisibility(item.id);
     editorEngine?.sceneManager?.hideObject(item.id);
+    editorEngine?.history.recordSetVisible(item.id, before, !before);
   };
 
   return (

frontend/apps/artcraft/app/src/pages/PageScene/engine/editor.ts

@@ -171,6 +171,8 @@ class Editor {
         const selected = this.sceneManager?.selected_objects?.[0];
         if (selected) this.gizmo.attach(selected);
       },
+      recordLockChange: (uuid, before, after) =>
+        this.history.recordSetLocked(uuid, before, after),
     });
 
     this.activeScene = new Scene(
@@ -732,6 +734,9 @@ class Editor {
   }
 
   deleteObject(uuid: string) {
+    // Snapshot for the undo stack before the object is gone.
+    const obj = this.activeScene.scene.getObjectByProperty("uuid", uuid);
+    if (obj) this.history.recordDelete(obj);
     this.mouse_controls?.clearFKVisuals();
     this.mouse_controls?.removeTransformControls(true);
     this.utils.deleteObject(uuid);

frontend/apps/artcraft/app/src/pages/PageScene/engine/editor/SelectionBridge.ts

@@ -29,6 +29,9 @@ export type SelectionBridgeDeps = {
   isObjectLocked: (uuid: string) => boolean;
   removeTransformControls: () => void;
   attachGizmoToCurrentSelection: () => void;
+  // Push a lock-toggle entry onto the undo stack. Optional so the bridge
+  // can be constructed before HistoryManager (and to keep tests simple).
+  recordLockChange?: (uuid: string, before: boolean, after: boolean) => void;
 };
 
 export class SelectionBridge {
@@ -46,6 +49,7 @@ export class SelectionBridge {
   // the gizmo (lock) or re-attach it to the current selection (unlock).
   // Returns the new locked state.
   lockUnlockObject(object_uuid: string): boolean {
+    const before = this.engine.isObjectLocked(object_uuid);
     const locked = this.engine.toggleObjectLocked(object_uuid);
     if (locked) {
       this.engine.removeTransformControls();
@@ -53,6 +57,7 @@ export class SelectionBridge {
       this.engine.attachGizmoToCurrentSelection();
     }
     this.updateSelectedUI();
+    this.engine.recordLockChange?.(object_uuid, before, locked);
     return locked;
   }
 

frontend/apps/artcraft/app/src/pages/PageScene/engine/keymap.ts

@@ -34,8 +34,10 @@ const setGizmoMode = (
 const deleteSelected = (editor: Editor) => {
   const mc = editor.mouse_controls;
   if (!mc?.selected) return;
+  // Route through editor.deleteObject so HistoryManager records the
+  // deletion. mc.deleteObject (the legacy direct path) bypasses history.
   mc.selected.forEach((sel) => {
-    mc.deleteObject(sel.uuid);
+    editor.deleteObject(sel.uuid);
   });
   mc.selected = [];
   mc.removeTransformControls();
@@ -70,11 +72,11 @@ const openAssetModal = () => {
 };
 
 const undo = async (editor: Editor) => {
-  await editor.sceneManager?.undo();
+  await editor.history.undo();
 };
 
 const redo = async (editor: Editor) => {
-  await editor.sceneManager?.redo();
+  await editor.history.redo();
 };
 
 const copy = async (editor: Editor) => {
@@ -82,7 +84,8 @@ const copy = async (editor: Editor) => {
 };
 
 const paste = async (editor: Editor) => {
-  await editor.sceneManager?.paste();
+  const obj = await editor.sceneManager?.paste();
+  if (obj) editor.history.recordCreate(obj);
 };
 
 export const buildKeymap = (): KeyBinding[] => [

frontend/apps/artcraft/app/src/pages/PageScene/engine/scene_manager_api.ts

@@ -306,7 +306,7 @@ export class SceneManager implements SceneManagerAPI {
     }
   }
 
-  public async paste() {
+  public async paste(): Promise<THREE.Object3D | undefined> {
     if (this.copiedObject && this.copiedObject.name != "::CAM::") {
       const userdata = this.copiedObject.userData;
       const position = this.copiedObject.position.clone();
@@ -353,8 +353,9 @@ export class SceneManager implements SceneManagerAPI {
       }
 
       await this.copy();
-      await this.add_creation_undostack(obj);
+      return obj;
     }
+    return undefined;
   }
 
   public onMouseMove(event: MouseEvent) {