收口创作代理聊天空态与输入框

将 creation-agent 聊天空态迁移到 PlatformEmptyState

将 creation-agent composer 文本域迁移到 PlatformTextField

补充空态输入框样式和键盘提交语义测试

更新 PlatformUiKit 文档和 Hermes 决策记录

src/components/creation-agent/CreationAgentWorkspace.test.tsx

@@ -99,11 +99,58 @@ test('creation agent workspace keeps initial chat progress at zero percent', ()
   ).toContain('rounded-[1.5rem]');
   expect(documentUploadButton.className).toContain('platform-icon-button');
   expect(referenceUploadButton.className).toContain('platform-icon-button');
+  const emptyState = screen.getByText('暂无消息');
+  const composer = screen.getByPlaceholderText('输入消息');
+
+  expect(emptyState.className).toContain('platform-empty-state');
+  expect(emptyState.className).toContain('h-full');
+  expect(composer.className).toContain('platform-text-field');
+  expect(composer.className).toContain('min-h-[3rem]');
+  expect(composer.className).toContain('flex-1');
   expect(
     (progressbar.firstElementChild as HTMLElement | null)?.style.width,
   ).toBe('0%');
 });
 
+test('creation agent workspace keeps composer keyboard submit semantics', () => {
+  ensureScrollApis();
+
+  const onSubmitText = vi.fn();
+  render(
+    <CreationAgentWorkspace
+      session={{
+        sessionId: 'creation-agent-session-1',
+        title: null,
+        currentTurn: 0,
+        progressPercent: 0,
+        anchors: [],
+        messages: [],
+      }}
+      theme={testTheme}
+      loadingText="正在准备"
+      composerPlaceholder="输入消息"
+      primaryActionLabel="生成结果页"
+      onBack={() => {}}
+      onSubmitText={onSubmitText}
+      onPrimaryAction={() => {}}
+    />,
+  );
+
+  const composer = screen.getByPlaceholderText('输入消息') as HTMLTextAreaElement;
+
+  fireEvent.change(composer, {
+    target: { value: '  继续推进设定  ' },
+  });
+  fireEvent.keyDown(composer, { key: 'Enter', shiftKey: true });
+
+  expect(onSubmitText).not.toHaveBeenCalled();
+
+  fireEvent.keyDown(composer, { key: 'Enter' });
+
+  expect(onSubmitText).toHaveBeenCalledWith('继续推进设定');
+  expect(composer.value).toBe('');
+});
+
 test('creation agent workspace renders operation banner with shared status message', () => {
   ensureScrollApis();
 

src/components/creation-agent/CreationAgentWorkspace.tsx

@@ -9,10 +9,12 @@ import {
   resolveCreationAgentProgressHint,
 } from '../../services/creation-agent';
 import { PlatformActionButton } from '../common/PlatformActionButton';
+import { PlatformEmptyState } from '../common/PlatformEmptyState';
 import { PlatformIconButton } from '../common/PlatformIconButton';
 import { PlatformProgressBar } from '../common/PlatformProgressBar';
 import { PlatformStatusMessage } from '../common/PlatformStatusMessage';
 import { PlatformSubpanel } from '../common/PlatformSubpanel';
+import { PlatformTextField } from '../common/PlatformTextField';
 import { PlatformUploadPreviewCard } from '../common/PlatformUploadPreviewCard';
 
 export type CreationAgentAnchorView = {
@@ -577,9 +579,14 @@ export function CreationAgentWorkspace({
             className="min-h-0 flex-1 space-y-3 overflow-y-auto px-4 py-4"
           >
             {displayedMessages.length === 0 ? (
-              <div className="flex h-full items-center justify-center text-sm text-[var(--platform-text-soft)]">
+              <PlatformEmptyState
+                surface="subpanel"
+                size="compact"
+                tone="soft"
+                className="flex h-full items-center justify-center text-center"
+              >
                 暂无消息
-              </div>
+              </PlatformEmptyState>
             ) : (
               displayedMessages.map((message, index) => (
                 <CreationAgentMessageBubble
@@ -672,12 +679,15 @@ export function CreationAgentWorkspace({
                   className="h-11 w-11 shrink-0"
                 />
               ) : null}
-              <textarea
+              <PlatformTextField
+                variant="textarea"
                 value={draftText}
                 disabled={
                   isBusy || isParsingDocumentInput || isReadingReferenceImage
                 }
                 rows={2}
+                size="md"
+                density="compact"
                 onChange={(event) => {
                   setDraftText(event.target.value);
                   setDocumentInputError(null);
@@ -689,7 +699,7 @@ export function CreationAgentWorkspace({
                   }
                 }}
                 placeholder={composerPlaceholder}
-                className="min-h-[3rem] flex-1 resize-none bg-transparent px-2 py-2 text-sm text-[var(--platform-text-strong)] outline-none placeholder:text-[var(--platform-text-soft)]"
+                className="min-h-[3rem] min-w-0 flex-1 placeholder:text-[var(--platform-text-soft)]"
               />
               <button
                 type="button"