统一画布代理文本与附件输入约束

要求用户消息包含非空文本，附件仅作为消息上下文。
同步后端领域校验、接口错误和请求测试。
禁用前端纯附件发送并更新交互回归测试。
保留发送失败时的草稿与附件恢复行为。

src/components/image-editor/EditorAgentConversation/EditorAgentConversationPanelView.test.tsx

@@ -24,6 +24,7 @@ import { EditorAgentConversationPanelView } from './EditorAgentConversationPanel
 const createEditorProjectResourceMock = vi.hoisted(() => vi.fn());
 const uploadEditorMediaAssetFileMock = vi.hoisted(() => vi.fn());
 const probeImageFileDimensionsMock = vi.hoisted(() => vi.fn());
+const ATTACHMENT_PROMPT = '请参考附件';
 
 vi.mock('@/src/services/image-editor/editorProjectClient.ts', async () => {
   const actual = await vi.importActual<
@@ -116,6 +117,12 @@ function createClient(): EditorAgentConversationClient {
   };
 }
 
+function enterAttachmentPrompt() {
+  fireEvent.change(screen.getByLabelText('发送给画布 Agent'), {
+    target: { value: ATTACHMENT_PROMPT },
+  });
+}
+
 afterEach(() => {
   vi.useRealTimers();
 });
@@ -425,13 +432,14 @@ describe('EditorAgentConversationPanelView', () => {
     fireEvent.click(screen.getByRole('menuitem', { name: '引用' }));
 
     expect(await screen.findByText('Agent生成图片-1')).toBeTruthy();
+    enterAttachmentPrompt();
     fireEvent.click(screen.getByRole('button', { name: '发送' }));
 
     await waitFor(() => {
       expect(client.sendMessage).toHaveBeenCalledWith(
         'conversation-1',
         expect.objectContaining({
-          text: '',
+          text: ATTACHMENT_PROMPT,
           attachments: [
             expect.objectContaining({
               source: 'canvas_resource',
@@ -792,13 +800,14 @@ describe('EditorAgentConversationPanelView', () => {
       expect(screen.getByText('粘贴图片')).toBeTruthy();
     });
 
+    enterAttachmentPrompt();
     fireEvent.click(screen.getByRole('button', { name: '发送' }));
 
     await waitFor(() => {
       expect(client.sendMessage).toHaveBeenCalledWith(
         'conversation-1',
         expect.objectContaining({
-          text: '',
+          text: ATTACHMENT_PROMPT,
           attachments: [
             expect.objectContaining({
               source: 'canvas_resource',
@@ -864,6 +873,7 @@ describe('EditorAgentConversationPanelView', () => {
       expect(screen.getByText('历史粘贴图')).toBeTruthy();
     });
 
+    enterAttachmentPrompt();
     fireEvent.click(screen.getByRole('button', { name: '发送' }));
     await waitFor(() => {
       expect(client.sendMessage).toHaveBeenCalledWith(
@@ -950,6 +960,7 @@ describe('EditorAgentConversationPanelView', () => {
     });
     expect(screen.queryByText('最新附件')).toBeNull();
 
+    enterAttachmentPrompt();
     fireEvent.click(screen.getByRole('button', { name: '发送' }));
     await waitFor(() => {
       expect(client.sendMessage).toHaveBeenCalledWith(
@@ -1080,6 +1091,7 @@ describe('EditorAgentConversationPanelView', () => {
     });
     expect(await screen.findByText('粘贴图片')).toBeTruthy();
 
+    enterAttachmentPrompt();
     fireEvent.click(screen.getByRole('button', { name: '发送' }));
     await waitFor(() => {
       expect(client.sendMessage).toHaveBeenCalledWith(
@@ -1222,6 +1234,7 @@ describe('EditorAgentConversationPanelView', () => {
     expect(await screen.findByText('最多 9 张')).toBeTruthy();
     expect(screen.queryByText('粘贴图片')).toBeNull();
 
+    enterAttachmentPrompt();
     fireEvent.click(screen.getByRole('button', { name: '发送' }));
     await waitFor(() => {
       const request = vi.mocked(client.sendMessage).mock.calls[0]?.[1];
@@ -1239,7 +1252,7 @@ describe('EditorAgentConversationPanelView', () => {
     });
   });
 
-  it('sends selected attachments even when the text input is empty', async () => {
+  it('rejects selected attachments when the text input is empty', async () => {
     const client = createClient();
 
     render(
@@ -1282,23 +1295,15 @@ describe('EditorAgentConversationPanelView', () => {
     fireEvent.click(
       within(attachmentDialog).getByRole('button', { name: '应用' }),
     );
-    fireEvent.click(screen.getByRole('button', { name: '发送' }));
+    const sendButton = screen.getByRole('button', {
+      name: '发送',
+    }) as HTMLButtonElement;
+    expect(sendButton.disabled).toBe(true);
 
-    await waitFor(() => {
-      expect(client.sendMessage).toHaveBeenCalledWith(
-        'conversation-1',
-        expect.objectContaining({
-          text: '',
-          attachments: [
-            expect.objectContaining({
-              source: 'canvas_resource',
-              referenceId: 'resource-1',
-            }),
-          ],
-        }),
-        expect.any(Object),
-      );
-    });
+    fireEvent.submit(sendButton.closest('form')!);
+
+    expect(client.sendMessage).not.toHaveBeenCalled();
+    expect(screen.getByText('角色图层')).toBeTruthy();
   });
 
   it('restores the draft and selected attachments when sending fails', async () => {
@@ -1464,6 +1469,7 @@ describe('EditorAgentConversationPanelView', () => {
     fireEvent.click(
       within(attachmentDialog).getByRole('button', { name: '应用' }),
     );
+    enterAttachmentPrompt();
     fireEvent.click(screen.getByRole('button', { name: '发送' }));
 
     await waitFor(() => {
@@ -1548,6 +1554,7 @@ describe('EditorAgentConversationPanelView', () => {
     fireEvent.click(
       within(attachmentDialog).getByRole('button', { name: '应用' }),
     );
+    enterAttachmentPrompt();
     fireEvent.click(screen.getByRole('button', { name: '发送' }));
 
     await waitFor(() => {
@@ -1659,6 +1666,7 @@ describe('EditorAgentConversationPanelView', () => {
     fireEvent.click(
       within(attachmentDialog).getByRole('button', { name: '应用' }),
     );
+    enterAttachmentPrompt();
     fireEvent.click(screen.getByRole('button', { name: '发送' }));
 
     await waitFor(() => {