fix(design): connect video preparation and playable history

tests/unit/youth-creation-card.test.tsx

@@ -5,6 +5,7 @@ import { YouthCreationCard } from '@/pages/ImageCanvas/YouthCreationCard';
 import { useImageWorkspaceStore } from '@/stores/image-workspace';
 import type { DesignGenerationTask } from '../../shared/image-workspace';
 import {
+  designCapabilitiesFixture,
   designFormFixture,
   designQuoteFixture,
   designValuesFixture,
@@ -60,6 +61,7 @@ function taskFixture(overrides: Partial<DesignGenerationTask> = {}): DesignGener
 function renderCard(workspace = designWorkspaceFixture()) {
   const actions = {
     applyFieldOperations: vi.fn().mockResolvedValue(workspace),
+    prepareGeneration: vi.fn().mockResolvedValue(workspace),
     requestQuote: vi.fn().mockResolvedValue(workspace),
     confirmGeneration: vi.fn().mockResolvedValue(workspace),
   };
@@ -74,6 +76,7 @@ function renderCard(workspace = designWorkspaceFixture()) {
       workspace={workspace}
       quoteBlockers={[]}
       generationAvailable
+      generationOptions={designCapabilitiesFixture.generationOptions}
       onQuoteOffered={vi.fn()}
     />,
   );
@@ -120,6 +123,42 @@ describe('YouthCreationCard', () => {
     useImageWorkspaceStore.getState().reset();
   });
 
+  it('persists the displayed supported duration when entering video mode', async () => {
+    const actions = renderCard();
+    fireEvent.change(screen.getByRole('combobox', { name: '类型' }), { target: { value: 'video' } });
+    await waitFor(() => expect(actions.prepareGeneration).toHaveBeenCalledWith([
+      { kind: 'set', path: 'intent.media', value: 'video' },
+      { kind: 'set', path: 'video.total_duration_seconds', value: 6 },
+    ]));
+    expect(actions.confirmGeneration).not.toHaveBeenCalled();
+  });
+
+  it('does not invent generation capabilities while the capability response is missing', () => {
+    render(<YouthCreationCard workspace={designWorkspaceFixture()} quoteBlockers={[]} generationAvailable />);
+    expect(screen.getByRole('button', { name: '准备制作方案' })).toBeDisabled();
+    expect(screen.getByRole('option', { name: '视频' })).toBeDisabled();
+  });
+
+  it('restores the saved medium if conversion cannot be prepared', async () => {
+    const actions = renderCard();
+    actions.prepareGeneration.mockRejectedValueOnce(new Error('preparation failed'));
+    fireEvent.change(screen.getByRole('combobox', { name: '类型' }), { target: { value: 'video' } });
+    await waitFor(() => expect(screen.getByRole('combobox', { name: '类型' })).toHaveValue('image'));
+    expect(screen.getByText('方案需要重试')).toBeInTheDocument();
+  });
+
+  it('unbinds the starting picture when its reference is explicitly removed', async () => {
+    const workspace = referenceWorkspace();
+    workspace.form.specification.values.intent.media = 'video';
+    workspace.form.specification.values.video.first_frame_asset_id = 'asset-reference';
+    workspace.form.specification.values.references[0].role = 'first_frame';
+    const actions = renderCard(workspace);
+    fireEvent.click(screen.getByRole('button', { name: '删除参考图 1' }));
+    await waitFor(() => expect(actions.applyFieldOperations).toHaveBeenCalledWith(expect.arrayContaining([
+      { kind: 'clear', path: 'video.first_frame_asset_id' },
+    ])));
+  });
+
   it('keeps the editable prompt and visible parameters in a lightweight inline plan', () => {
     renderCard();