fix: capture update starts without context

setAttributesAndPreventAnimate may run before consumers attach context.diffAttrs.

It still overwrites transient attributes with final update values.

Capture the pre-handoff frame from submitted attrs when no context diff exists.

Update can later consume the same key/value target instead of reading final attribute.

Constraint: VChart update can call prevent-animate before attaching diffAttrs

Rejected: Require consumers to attach diffAttrs first | leaks VRender ordering

Rejected: Read starts from baseAttributes | breaks interrupted transient handoff

Confidence: high

Scope-risk: narrow

Directive: Keep update start snapshots Graphic-owned and transient-only

Tested: vrender-animate targeted regression red then green

Tested: vrender-animate rushx test

Tested: vrender-core state animation and transition targeted tests

Tested: rush compile for vrender-core and vrender-animate

Tested: vrender-core eslint; animation perf smoke; git diff --check

Not-tested: VChart browser consumer smoke

Author: xuefei1313

packages/vrender-animate/__tests__/unit/animation-runtime-attribute.test.ts

@@ -1,8 +1,16 @@
-import { application, createGroup, createLine, createRect, DefaultGraphicService } from '@visactor/vrender-core';
+import {
+  application,
+  AttributeUpdateType,
+  createGroup,
+  createLine,
+  createRect,
+  DefaultGraphicService
+} from '@visactor/vrender-core';
 import { registerAnimate } from '../../src/register';
 import { registerCustomAnimate } from '../../src/custom/register';
 import { AnimateExecutor } from '../../src/executor/animate-executor';
 import { TagPointsUpdate } from '../../src/custom/tag-points';
+import { Update } from '../../src/custom/update';
 import { DefaultTimeline } from '../../src/timeline';
 import { ManualTicker } from '../../src/ticker/manual-ticker';
 
@@ -1070,6 +1078,53 @@ describe('D3 pre-handoff animation runtime', () => {
     expect(rect.getFinalAttribute().height).toBe(next.height);
   });
 
+  test('update animation captures start attrs when diff context is attached after prevent-animate handoff', () => {
+    ensureAnimationRuntime();
+
+    const oldY = 46.90909090909094;
+    const finalY = 3;
+    const rect = createRect({
+      x: 0,
+      y: oldY,
+      width: 10,
+      height: 34
+    });
+    rect.setFinalAttributes({ ...rect.attribute });
+
+    const diffAttrs = {
+      x: 974.1100285714286,
+      y: finalY,
+      height: 34
+    };
+
+    rect.setAttributesAndPreventAnimate(diffAttrs, false, {
+      type: AttributeUpdateType.DEFAULT
+    });
+
+    expect(rect.attribute.y).toBe(finalY);
+    expect((rect as any).baseAttributes.y).toBeCloseTo(oldY);
+
+    (rect as any).context = {
+      diffAttrs,
+      finalAttrs: diffAttrs
+    };
+
+    const animate = rect.animate().play(new Update(null, null, 300, 'linear', {} as any));
+    animate.advance(1);
+
+    const step = (animate as any)._firstStep;
+    expect(step.getFromProps().y).toBeCloseTo(oldY);
+    expect(step.getEndProps().y).toBe(finalY);
+    expect(rect.attribute.y).toBeGreaterThan(finalY);
+    expect(rect.attribute.y).toBeLessThan(oldY);
+
+    animate.advance(300);
+
+    expect(rect.attribute.y).toBe(finalY);
+    expect((rect as any).baseAttributes.y).toBe(finalY);
+    expect(rect.getFinalAttribute().y).toBe(finalY);
+  });
+
   test('superseded executor update cannot commit stale layout when it ends late', () => {
     const { group, ticker, graphicService } = createStageHarness('executor-update-stale-end');
     const threeItemLayout = {

packages/vrender-core/src/graphic/graphic.ts

@@ -1329,11 +1329,10 @@ export abstract class Graphic<T extends Partial<IGraphicAttribute> = Partial<IGr
     context?: ISetAttributeContext
   ) {
     const graphicContext = this.context as Record<string, any> | undefined;
-    const diffAttrs = graphicContext?.diffAttrs as Record<string, any> | undefined;
+    const diffAttrs = (graphicContext?.diffAttrs as Record<string, any> | undefined) ?? (params as Record<string, any>);
     const updateType = context?.type;
     if (
       !keys.length ||
-      !graphicContext ||
       !diffAttrs ||
       updateType === AttributeUpdateType.STATE ||
       (updateType != null &&