fix: md 预览代码块复制按钮跟随 DSH i18n（MarkdownText 补传 codeLabels）

tests/markdown-copy-labels.spec.tsx

@@ -0,0 +1,73 @@
+/**
+ * Markdown preview copy-label spec: the fence copy buttons ("复制" / "Copy")
+ * must follow the DSH locale service through `codeLabels` — the DSH
+ * MarkdownText/CodeBlock are cordis-free and fall back to HARDCODED Chinese
+ * when the caller omits the labels, so TextEditor must pass its own
+ * dictionary copy (`t('copy')` / `t('copied')`), re-evaluated per render.
+ * Rendered with renderToString (the initial preview mode never mounts
+ * CodeMirror, so no DOM/effects are needed).
+ */
+import { describe, expect, it, afterEach } from 'vitest'
+import { renderToString } from 'react-dom/server'
+import { createElement } from 'react'
+import './browser-globals.ts'
+import { TextEditor } from '../src/client/TextEditor.tsx'
+import { createSidebarStore } from '../src/client/state.ts'
+import { attachLocale } from '../src/client/locales.ts'
+import type { FileViewerProps } from '../src/client/service.ts'
+
+/** Minimal structural fake of the DSH LocaleService face the sidebar uses. */
+class FakeLocale {
+  active: string = 'zh'
+  getSnapshot(): { active: string } {
+    return { active: this.active }
+  }
+  subscribe(_fn: () => void): () => void {
+    return () => {}
+  }
+  register(_ns: string, _locale: string, _dict: Record<string, string>): () => void {
+    return () => {}
+  }
+}
+
+const CTX = {} as Parameters<typeof TextEditor>[0]['ctx']
+
+/** A markdown source with one fenced code block (the copy-button surface). */
+const MD_WITH_FENCE = '```ts\nconst a = 1\n```'
+
+function viewerProps(overrides: Partial<FileViewerProps> = {}): FileViewerProps {
+  return {
+    ctx: CTX,
+    store: createSidebarStore(),
+    scope: { sessionId: 's1', cwd: '/p' },
+    path: '/p/a/README.md',
+    title: 'README.md',
+    viewerId: 'markdown',
+    content: MD_WITH_FENCE,
+    ...overrides,
+  }
+}
+
+afterEach(() => {
+  attachLocale(undefined)
+})
+
+describe('markdown preview code-block copy labels (DSH i18n following)', () => {
+  it('renders the fence copy button with the zh dictionary label by default', () => {
+    const locale = new FakeLocale()
+    locale.active = 'zh'
+    attachLocale(locale)
+    const html = renderToString(createElement(TextEditor, viewerProps()))
+    expect(html).toContain('复制')
+    expect(html).not.toContain('Copy')
+  })
+
+  it('follows the attached locale service live: en renders "Copy" instead of the zh label', () => {
+    const locale = new FakeLocale()
+    locale.active = 'en'
+    attachLocale(locale)
+    const html = renderToString(createElement(TextEditor, viewerProps()))
+    expect(html).toContain('Copy')
+    expect(html).not.toContain('复制')
+  })
+})