fix(design): connect video preparation and playable history

tests/unit/video-first-frame.test.ts

@@ -0,0 +1,89 @@
+import { describe, expect, it } from 'vitest';
+import { createVideoFirstFrameOperations } from '@/pages/ImageCanvas/video-first-frame';
+import {
+  designFormFixture,
+  designValuesFixture,
+  designWorkspaceFixture,
+} from '../fixtures/design-workspace-v2';
+import type { DesignAsset } from '../../shared/image-workspace';
+
+const imageAsset: DesignAsset = {
+  assetId: 'asset-first-frame',
+  workspaceId: 'workspace-1',
+  role: 'uploaded',
+  mediaType: 'image',
+  mimeType: 'image/png',
+  width: 720,
+  height: 1280,
+  durationMilliseconds: null,
+  generationTaskId: null,
+  createdAt: '2026-09-16T00:00:00Z',
+  contentPath: '/api/design/assets/asset-first-frame/content',
+};
+
+describe('video first-frame binding', () => {
+  it('adds an explicit first-frame reference without deleting the asset', () => {
+    const workspace = designWorkspaceFixture();
+    const result = createVideoFirstFrameOperations(workspace, imageAsset);
+
+    expect(result.nextPrompt).toContain('@图片1');
+    expect(result.operations).toEqual(expect.arrayContaining([
+      { kind: 'set', path: 'video.first_frame_asset_id', value: imageAsset.assetId },
+      expect.objectContaining({ kind: 'set', path: 'references' }),
+      expect.objectContaining({ kind: 'set', path: 'content.concept' }),
+    ]));
+    const referencesOperation = result.operations.find((operation) => operation.path === 'references');
+    expect(referencesOperation).toMatchObject({
+      value: [expect.objectContaining({ asset_id: imageAsset.assetId, role: 'first_frame' })],
+    });
+  });
+
+  it('promotes an existing reference and demotes the old first frame in place', () => {
+    const values = structuredClone(designValuesFixture);
+    values.intent.media = 'video';
+    values.references = [
+      {
+        id: 'reference-old',
+        asset_id: 'asset-old',
+        asset_revision: null,
+        role: 'first_frame',
+        preserve: [],
+        adapt: [],
+        do_not_copy: [],
+        reviewed_observations: [],
+      },
+      {
+        id: 'reference-next',
+        asset_id: imageAsset.assetId,
+        asset_revision: null,
+        role: 'inspiration',
+        preserve: [],
+        adapt: [],
+        do_not_copy: [],
+        reviewed_observations: [],
+      },
+    ];
+    values.video.first_frame_asset_id = 'asset-old';
+    values.content.concept = '参考 @图片1 和 @图片2 的画面';
+    const workspace = designWorkspaceFixture({
+      form: designFormFixture({
+        specification: { schema_version: 1, values, field_decisions: {} },
+      }),
+    });
+
+    const result = createVideoFirstFrameOperations(workspace, imageAsset);
+    const referencesOperation = result.operations.find((operation) => operation.path === 'references');
+    expect(referencesOperation).toMatchObject({
+      value: [
+        expect.objectContaining({ asset_id: 'asset-old', role: 'inspiration' }),
+        expect.objectContaining({ asset_id: imageAsset.assetId, role: 'first_frame' }),
+      ],
+    });
+    expect(result.operations).toContainEqual({
+      kind: 'set',
+      path: 'video.first_frame_asset_id',
+      value: imageAsset.assetId,
+    });
+    expect(result.nextPrompt).toBe('参考 @图片1 和 @图片2 的画面');
+  });
+});