feat: improve grouping perf in edgeless (#14442)

fix #14433 

#### PR Dependency Tree


* **PR #14442** 👈

This tree was auto-generated by
[Charcoal](https://github.com/danerwilliams/charcoal)

<!-- This is an auto-generated comment: release notes by coderabbit.ai
-->
## Summary by CodeRabbit

* **New Features**
  * Level-of-detail thumbnails for large images.
  * Adaptive pacing for snapping, distribution and other alignment work.
  * RAF coalescer utility to batch high-frequency updates.
  * Operation timing utility to measure synchronous work.

* **Improvements**
* Batch group/ungroup reparenting that preserves element order and
selection.
  * Coalesced panning and drag updates to reduce jitter.
* Connector/group indexing for more reliable updates, deletions and
sync.
  * Throttled viewport refresh behavior.

* **Documentation**
  * Docs added for RAF coalescer and measureOperation.
<!-- end of auto-generated comment: release notes by coderabbit.ai -->

blocksuite/affine/gfx/pointer/src/__tests__/adaptive-load-controller.unit.spec.ts

@@ -0,0 +1,73 @@
+import { describe, expect, test } from 'vitest';
+
+import {
+  AdaptiveCooldownController,
+  AdaptiveStrideController,
+} from '../snap/adaptive-load-controller.js';
+
+describe('AdaptiveStrideController', () => {
+  test('increases stride under heavy cost and respects maxStride', () => {
+    const controller = new AdaptiveStrideController({
+      heavyCostMs: 6,
+      maxStride: 3,
+      recoveryCostMs: 2,
+    });
+
+    controller.reportCost(10);
+    controller.reportCost(12);
+    controller.reportCost(15);
+
+    // stride should be capped at 3, so only every 3rd tick runs.
+    expect(controller.shouldSkip()).toBe(false);
+    expect(controller.shouldSkip()).toBe(true);
+    expect(controller.shouldSkip()).toBe(true);
+    expect(controller.shouldSkip()).toBe(false);
+  });
+
+  test('decreases stride when cost recovers and reset clears state', () => {
+    const controller = new AdaptiveStrideController({
+      heavyCostMs: 8,
+      maxStride: 4,
+      recoveryCostMs: 3,
+    });
+
+    controller.reportCost(12);
+    controller.reportCost(12);
+    controller.reportCost(1);
+
+    // From stride 3 recovered to stride 2: run every other tick.
+    expect(controller.shouldSkip()).toBe(false);
+    expect(controller.shouldSkip()).toBe(true);
+    expect(controller.shouldSkip()).toBe(false);
+
+    controller.reset();
+    expect(controller.shouldSkip()).toBe(false);
+    expect(controller.shouldSkip()).toBe(false);
+  });
+});
+
+describe('AdaptiveCooldownController', () => {
+  test('enters cooldown when cost exceeds threshold', () => {
+    const controller = new AdaptiveCooldownController({
+      cooldownFrames: 2,
+      maxCostMs: 5,
+    });
+
+    controller.reportCost(9);
+    expect(controller.shouldRun()).toBe(false);
+    expect(controller.shouldRun()).toBe(false);
+    expect(controller.shouldRun()).toBe(true);
+  });
+
+  test('reset exits cooldown immediately', () => {
+    const controller = new AdaptiveCooldownController({
+      cooldownFrames: 3,
+      maxCostMs: 5,
+    });
+
+    controller.reportCost(6);
+    expect(controller.shouldRun()).toBe(false);
+    controller.reset();
+    expect(controller.shouldRun()).toBe(true);
+  });
+});

blocksuite/affine/gfx/pointer/src/__tests__/pan-tool.unit.spec.ts

@@ -0,0 +1,177 @@
+import { EdgelessLegacySlotIdentifier } from '@blocksuite/affine-block-surface';
+import { MouseButton } from '@blocksuite/std/gfx';
+import { afterEach, describe, expect, test, vi } from 'vitest';
+
+import { PanTool } from '../tools/pan-tool.js';
+
+type PointerDownHandler = (event: {
+  raw: {
+    button: number;
+    preventDefault: () => void;
+  };
+}) => unknown;
+
+const mockRaf = () => {
+  let callback: FrameRequestCallback | undefined;
+  const requestAnimationFrameMock = vi
+    .fn()
+    .mockImplementation((cb: FrameRequestCallback) => {
+      callback = cb;
+      return 1;
+    });
+  const cancelAnimationFrameMock = vi.fn();
+
+  vi.stubGlobal('requestAnimationFrame', requestAnimationFrameMock);
+  vi.stubGlobal('cancelAnimationFrame', cancelAnimationFrameMock);
+
+  return {
+    getCallback: () => callback,
+    requestAnimationFrameMock,
+    cancelAnimationFrameMock,
+  };
+};
+
+const createToolFixture = (options?: {
+  currentToolName?: string;
+  currentToolOptions?: Record<string, unknown>;
+}) => {
+  const applyDeltaCenter = vi.fn();
+  const selectionSet = vi.fn();
+  const setTool = vi.fn();
+  const navigatorSettingUpdated = {
+    next: vi.fn(),
+  };
+  const currentToolName = options?.currentToolName;
+  const currentToolOption = {
+    toolType: currentToolName
+      ? ({
+          toolName: currentToolName,
+        } as any)
+      : undefined,
+    options: options?.currentToolOptions,
+  };
+
+  const gfx = {
+    viewport: {
+      zoom: 2,
+      applyDeltaCenter,
+    },
+    selection: {
+      surfaceSelections: [{ elements: ['shape-1'] }],
+      set: selectionSet,
+    },
+    tool: {
+      currentTool$: {
+        peek: () => null,
+      },
+      currentToolOption$: {
+        peek: () => currentToolOption,
+      },
+      setTool,
+    },
+    std: {
+      get: (identifier: unknown) => {
+        if (identifier === EdgelessLegacySlotIdentifier) {
+          return { navigatorSettingUpdated };
+        }
+        return null;
+      },
+    },
+    doc: {},
+  };
+
+  const tool = new PanTool(gfx as any);
+
+  return {
+    applyDeltaCenter,
+    navigatorSettingUpdated,
+    selectionSet,
+    setTool,
+    tool,
+  };
+};
+
+afterEach(() => {
+  vi.unstubAllGlobals();
+});
+
+describe('PanTool', () => {
+  test('flushes accumulated delta on dragEnd', () => {
+    mockRaf();
+    const { tool, applyDeltaCenter } = createToolFixture();
+
+    tool.dragStart({ x: 100, y: 100 } as any);
+    tool.dragMove({ x: 80, y: 60 } as any);
+    tool.dragMove({ x: 70, y: 40 } as any);
+
+    expect(applyDeltaCenter).not.toHaveBeenCalled();
+    tool.dragEnd({} as any);
+
+    expect(applyDeltaCenter).toHaveBeenCalledTimes(1);
+    expect(applyDeltaCenter).toHaveBeenCalledWith(15, 30);
+    expect(tool.panning$.value).toBe(false);
+  });
+
+  test('cancel in unmounted drops pending deltas', () => {
+    mockRaf();
+    const { tool, applyDeltaCenter } = createToolFixture();
+
+    tool.dragStart({ x: 100, y: 100 } as any);
+    tool.dragMove({ x: 80, y: 60 } as any);
+    tool.unmounted();
+    tool.dragEnd({} as any);
+
+    expect(applyDeltaCenter).not.toHaveBeenCalled();
+  });
+
+  test('middle click temporary pan restores frameNavigator with restoredAfterPan', () => {
+    const { tool, navigatorSettingUpdated, selectionSet, setTool } =
+      createToolFixture({
+        currentToolName: 'frameNavigator',
+        currentToolOptions: { mode: 'fit' },
+      });
+
+    const hooks: Partial<Record<'pointerDown', PointerDownHandler>> = {};
+    (tool as any).eventTarget = {
+      addHook: (eventName: 'pointerDown', handler: PointerDownHandler) => {
+        hooks[eventName] = handler;
+      },
+    };
+
+    tool.mounted();
+
+    const preventDefault = vi.fn();
+    const pointerDown = hooks.pointerDown!;
+    const ret = pointerDown({
+      raw: {
+        button: MouseButton.MIDDLE,
+        preventDefault,
+      },
+    });
+
+    expect(ret).toBe(false);
+    expect(preventDefault).toHaveBeenCalledTimes(1);
+    expect(navigatorSettingUpdated.next).toHaveBeenCalledWith({
+      blackBackground: false,
+    });
+    expect(setTool).toHaveBeenNthCalledWith(1, PanTool, {
+      panning: true,
+    });
+
+    document.dispatchEvent(
+      new PointerEvent('pointerup', { button: MouseButton.MIDDLE })
+    );
+
+    expect(selectionSet).toHaveBeenCalledWith([{ elements: ['shape-1'] }]);
+    expect(setTool).toHaveBeenNthCalledWith(
+      2,
+      expect.objectContaining({
+        toolName: 'frameNavigator',
+      }),
+      {
+        mode: 'fit',
+        restoredAfterPan: true,
+      }
+    );
+  });
+});