! WARNING this pull request has changed these public interfaces:

@@ -3313,8 +3313,9 @@
         protected _textStyle: __private._cocos_2d_assembler_label_text_style__TextStyle | null;
         protected _textLayout: __private._cocos_2d_assembler_label_text_layout__TextLayout | null;
         protected _textRenderData: __private._cocos_2d_assembler_label_text_output_data__TextOutputRenderData | null;
         protected _textLayoutData: __private._cocos_2d_assembler_label_text_output_data__TextOutputLayoutData | null;
+        protected _layoutDirty: boolean;
         constructor();
         onEnable(): void;
         onDestroy(): void;
         /**
@@ -3332,8 +3333,9 @@
         protected _canRender(): boolean;
         protected _flushAssembler(): void;
         protected _applyFontTexture(): void;
         protected changeMaterialForDefine(): void;
+        protected _nodeStateChange(transformType: TransformBit): void;
     }
     /**
      * @deprecated since v3.5.0, this is an engine private interface that will be removed in the future.
      */
@@ -3373,10 +3375,8 @@
         protected _drawInfoType: __private._cocos_2d_renderer_render_draw_info__RenderDrawInfoType;
         protected _multiOwner: boolean;
         get multiOwner(): boolean;
         set multiOwner(val: boolean);
-        protected _batcher: UI | null;
-        get batcher(): UI;
         constructor(vertexFormat?: gfx.Attribute[]);
         isValid(): false | __private._cocos_2d_renderer_static_vb_accessor__StaticVBAccessor;
         initRenderDrawInfo(comp: UIRenderer, drawInfoType?: __private._cocos_2d_renderer_render_draw_info__RenderDrawInfoType): void;
         removeRenderDrawInfo(comp: UIRenderer): void;
@@ -3574,11 +3574,10 @@
      * @en UI rendering process
      * @zh UI 渲染流程
      */
     export class UI implements __private._cocos_2d_renderer_i_batcher__IBatcher {
-        protected _nativeObj: __private._cocos_2d_renderer_native_2d__NativeBatcher2d;
-        get nativeObj(): __private._cocos_2d_renderer_native_2d__NativeBatcher2d;
-        get currBufferAccessor(): __private._cocos_2d_renderer_static_vb_accessor__StaticVBAccessor;
+        static getInstance(): UI;
+        static getFirstRenderCamera(node: Node): renderer.scene.Camera | null;
         get batches(): memop.CachedArray<__private._cocos_2d_renderer_draw_batch__DrawBatch2D>;
         device: gfx.Device;
         constructor(_root: Root);
         initialize(): boolean;
@@ -3592,29 +3591,22 @@
          *
          * @param comp @en The render root of 2d.
          *             @zh 2d 渲染入口组件。
          */
-        addScreen(comp: RenderRoot2D): void;
+        addScreen(node: Node): void;
         /**
          * @zh
          * Removes the Canvas from the list.
          *
          * @param comp @en The target to removed.
          *             @zh 被移除的屏幕。
          */
-        removeScreen(comp: RenderRoot2D): void;
+        removeScreen(node: Node): void;
         sortScreens(): void;
-        getFirstRenderCamera(node: Node): renderer.scene.Camera | null;
         update(): void;
         uploadBuffers(): void;
         reset(): void;
-        /**
-         * @zh 如果有必要，为相应的顶点布局切换网格缓冲区。
-         * @en Switch the mesh buffer for corresponding vertex layout if necessary.
-         * @param attributes use VertexFormat.vfmtPosUvColor by default
-         */
-        switchBufferAccessor(attributes?: gfx.Attribute[]): __private._cocos_2d_renderer_static_vb_accessor__StaticVBAccessor;
-        registerBufferAccessor(key: number, accessor: __private._cocos_2d_renderer_static_vb_accessor__StaticVBAccessor): void;
+        syncMeshBuffersToNative(accId: number, buffers: __private._cocos_2d_renderer_native_2d__NativeUIMeshBuffer[]): void;
         updateBuffer(attributes: gfx.Attribute[], bid: number): void;
         /**
          * @en
          * Render component data submission process of UI.
@@ -3713,9 +3705,9 @@
          * 强制刷新材质。
          */
         flushMaterial(mat: Material): void;
         walk(node: Node, level?: number): void;
-        syncMeshBuffersToNative(accId: number, buffers: MeshBuffer[]): void;
+        releaseDescriptorSetCache(texture: __private._cocos_asset_assets_texture_base__TextureBase): void;
     }
     /**
      * @deprecated since v3.6.0, this is an engine private interface that will be removed in the future.
      * @internal
@@ -7766,8 +7758,9 @@
         get pipelineEvent(): __private._cocos_rendering_pipeline_event__IPipelineEvent;
         /**
          * @en The draw batch manager for 2D UI, for engine internal usage, user do not need to use this.
          * @zh 2D UI 渲染合批管理器，引擎内部使用，用户无需使用此接口
+         * @deprecated Since v3.9.0, this is an engine private interface that will be removed in the future.
          */
         get batcher2D(): UI;
         /**
          * @en Render scenes list
@@ -27322,8 +27315,14 @@
          * @zh 一帧结束之后所触发的事件。
          * @event Director.EVENT_END_FRAME
          */
         static readonly EVENT_END_FRAME = "director_end_frame";
+        /**
+         * @en The event which will be triggered at the time that UI system update.
+         * @zh UI系统开始更新时的事件。
+         * @event Director.EVENT_UPDATE_UI
+         */
+        static readonly EVENT_UPDATE_UI = "director_update_ui";
         static instance: Director;
         /**
          * @deprecated since v3.5.0, this is an engine private interface that will be removed in the future.
          */
@@ -59544,55 +59543,8 @@
             nuv: number[];
             minPos: math.Vec3;
             maxPos: math.Vec3;
         }
-        /**
-         * @internal
-         */
-        export class _cocos_2d_renderer_static_vb_accessor__StaticVBChunk {
-            vertexAccessor: _cocos_2d_renderer_static_vb_accessor__StaticVBAccessor;
-            bufferId: number;
-            meshBuffer: MeshBuffer;
-            vertexOffset: number;
-            vb: Float32Array;
-            indexCount: number;
-            get ib(): Readonly<Uint16Array>;
-            constructor(vertexAccessor: _cocos_2d_renderer_static_vb_accessor__StaticVBAccessor, bufferId: number, meshBuffer: MeshBuffer, vertexOffset: number, vb: Float32Array, indexCount: number);
-            setIndexBuffer(indices: ArrayLike<number>): void;
-        }
-        export class _cocos_2d_renderer_buffer_accessor__BufferAccessor {
-            get attributes(): Readonly<gfx.Attribute[]>;
-            get vertexFormatBytes(): number;
-            get floatsPerVertex(): number;
-            protected _device: gfx.Device;
-            protected _attributes: gfx.Attribute[];
-            protected _vertexFormatBytes: number;
-            protected _floatsPerVertex: number;
-            protected _buffers: MeshBuffer[];
-            constructor(device: gfx.Device, attributes: gfx.Attribute[]);
-            initialize(): void;
-            reset(): void;
-            request(vertexCount?: number, indexCount?: number): void;
-            appendBuffers(vertices: Float32Array, indices: Uint16Array): void;
-            uploadBuffers(): void;
-            destroy(): void;
-        }
-        export class _cocos_2d_renderer_static_vb_accessor__StaticVBAccessor extends _cocos_2d_renderer_buffer_accessor__BufferAccessor {
-            static IB_SCALE: number;
-            static ID_COUNT: number;
-            get id(): number;
-            constructor(device: gfx.Device, attributes: gfx.Attribute[], vCount?: number, iCount?: number);
-            destroy(): void;
-            reset(): void;
-            getVertexBuffer(bid: number): Float32Array;
-            getIndexBuffer(bid: number): Uint16Array;
-            getMeshBuffer(bid: number): MeshBuffer;
-            uploadBuffers(): void;
-            appendIndices(bufferId: number, indices: Uint16Array): void;
-            allocateChunk(vertexCount: number, indexCount: number): _cocos_2d_renderer_static_vb_accessor__StaticVBChunk | null;
-            recycleChunk(chunk: _cocos_2d_renderer_static_vb_accessor__StaticVBChunk): void;
-            static generateID(): number;
-        }
         export class _cocos_2d_renderer_draw_batch__DrawBatch2D {
             get inputAssembler(): gfx.InputAssembler | null;
             set inputAssembler(ia: gfx.InputAssembler | null);
             get descriptorSet(): gfx.DescriptorSet | null;
@@ -59611,21 +59563,18 @@
             clear(): void;
             fillPasses(mat: Material | null, dss: any, dssHash: any, patches: any): void;
         }
         export interface _cocos_2d_renderer_i_batcher__IBatcher {
-            currBufferAccessor: _cocos_2d_renderer_static_vb_accessor__StaticVBAccessor;
             readonly batches: memop.CachedArray<_cocos_2d_renderer_draw_batch__DrawBatch2D>;
             device: gfx.Device;
             initialize(): boolean;
             destroy(): any;
-            addScreen(comp: RenderRoot2D): any;
-            getFirstRenderCamera(node: Node): renderer.scene.Camera | null;
-            removeScreen(comp: RenderRoot2D): any;
+            addScreen(node: Node): any;
+            removeScreen(node: Node): any;
             sortScreens(): any;
             update(): any;
             uploadBuffers(): any;
             reset(): any;
-            switchBufferAccessor(attributes?: gfx.Attribute[]): _cocos_2d_renderer_static_vb_accessor__StaticVBAccessor;
             commitComp(comp: UIRenderer, renderData: BaseRenderData | null, frame: _cocos_asset_assets_texture_base__TextureBase | SpriteFrame | null, assembler: any, transform: Node | null): any;
             commitModel(comp: UIMeshRenderer | UIRenderer, model: renderer.scene.Model | null, mat: Material | null): any;
             autoMergeBatches(renderComp?: UIRenderer): any;
             forceMergeBatches(material: Material, frame: _cocos_asset_assets_texture_base__TextureBase | SpriteFrame | null, renderComp: UIRenderer): any;
@@ -60155,16 +60104,55 @@
             contentSizeExtend: math.Size;
             startPosition: math.Vec2;
             reset(): void;
         }
-        export class _cocos_2d_renderer_native_2d__NativeBatcher2d {
-            syncMeshBuffersToNative(accId: number, buffers: _cocos_2d_renderer_native_2d__NativeUIMeshBuffer[]): any;
-            update(): any;
-            uploadBuffers(): any;
-            reset(): any;
-            syncRootNodesToNative(nodes: Node[]): any;
-            releaseDescriptorSetCache(texture: gfx.Texture, sampler: gfx.Sampler): any;
+        export class _cocos_2d_renderer_buffer_accessor__BufferAccessor {
+            get attributes(): Readonly<gfx.Attribute[]>;
+            get vertexFormatBytes(): number;
+            get floatsPerVertex(): number;
+            protected _device: gfx.Device;
+            protected _attributes: gfx.Attribute[];
+            protected _vertexFormatBytes: number;
+            protected _floatsPerVertex: number;
+            protected _buffers: MeshBuffer[];
+            constructor(device: gfx.Device, attributes: gfx.Attribute[]);
+            initialize(): void;
+            reset(): void;
+            request(vertexCount?: number, indexCount?: number): void;
+            appendBuffers(vertices: Float32Array, indices: Uint16Array): void;
+            uploadBuffers(): void;
+            destroy(): void;
         }
+        export class _cocos_2d_renderer_static_vb_accessor__StaticVBAccessor extends _cocos_2d_renderer_buffer_accessor__BufferAccessor {
+            static IB_SCALE: number;
+            static ID_COUNT: number;
+            get id(): number;
+            constructor(device: gfx.Device, attributes: gfx.Attribute[], vCount?: number, iCount?: number);
+            destroy(): void;
+            reset(): void;
+            getVertexBuffer(bid: number): Float32Array;
+            getIndexBuffer(bid: number): Uint16Array;
+            getMeshBuffer(bid: number): MeshBuffer;
+            uploadBuffers(): void;
+            appendIndices(bufferId: number, indices: Uint16Array): void;
+            allocateChunk(vertexCount: number, indexCount: number): _cocos_2d_renderer_static_vb_accessor__StaticVBChunk | null;
+            recycleChunk(chunk: _cocos_2d_renderer_static_vb_accessor__StaticVBChunk): void;
+            static generateID(): number;
+        }
+        /**
+         * @internal
+         */
+        export class _cocos_2d_renderer_static_vb_accessor__StaticVBChunk {
+            vertexAccessor: _cocos_2d_renderer_static_vb_accessor__StaticVBAccessor;
+            bufferId: number;
+            meshBuffer: MeshBuffer;
+            vertexOffset: number;
+            vb: Float32Array;
+            indexCount: number;
+            get ib(): Readonly<Uint16Array>;
+            constructor(vertexAccessor: _cocos_2d_renderer_static_vb_accessor__StaticVBAccessor, bufferId: number, meshBuffer: MeshBuffer, vertexOffset: number, vb: Float32Array, indexCount: number);
+            setIndexBuffer(indices: ArrayLike<number>): void;
+        }
         export class _cocos_2d_utils_dynamic_atlas_atlas__DynamicAtlasTexture extends Texture2D {
             /**
              * @en
              * Initialize the render texture.