diff --git a/frontend/package.json b/frontend/package.json
index 92c3212..39d7157 100644
--- a/frontend/package.json
+++ b/frontend/package.json
@@ -11,8 +11,12 @@
     "type-check": "vue-tsc --noEmit"
   },
   "dependencies": {
+    "@codemirror/commands": "6.11.0",
     "@codemirror/lang-markdown": "^6.5.0",
+    "@codemirror/language": "6.12.4",
+    "@codemirror/state": "6.7.1",
     "@codemirror/theme-one-dark": "^6.1.0",
+    "@codemirror/view": "6.43.9",
     "@element-plus/icons-vue": "^2.3.2",
     "@milkdown/crepe": "7.22.1",
     "@milkdown/kit": "7.22.1",
diff --git a/frontend/pnpm-lock.yaml b/frontend/pnpm-lock.yaml
index 6ad34de..6d22fa8 100644
--- a/frontend/pnpm-lock.yaml
+++ b/frontend/pnpm-lock.yaml
@@ -8,12 +8,24 @@ importers:
 
   .:
     dependencies:
+      '@codemirror/commands':
+        specifier: 6.11.0
+        version: 6.11.0
       '@codemirror/lang-markdown':
         specifier: ^6.5.0
         version: 6.5.2
+      '@codemirror/language':
+        specifier: 6.12.4
+        version: 6.12.4
+      '@codemirror/state':
+        specifier: 6.7.1
+        version: 6.7.1
       '@codemirror/theme-one-dark':
         specifier: ^6.1.0
         version: 6.1.3
+      '@codemirror/view':
+        specifier: 6.43.9
+        version: 6.43.9
       '@element-plus/icons-vue':
         specifier: ^2.3.2
         version: 2.3.2(vue@3.5.41(typescript@5.9.3))
diff --git a/frontend/src/features/editor/VisualMarkdownEditor.spec.ts b/frontend/src/features/editor/VisualMarkdownEditor.spec.ts
index 2520ebe..a89bdbc 100644
--- a/frontend/src/features/editor/VisualMarkdownEditor.spec.ts
+++ b/frontend/src/features/editor/VisualMarkdownEditor.spec.ts
@@ -7,6 +7,9 @@ import { TextSelection } from '@milkdown/kit/prose/state'
 import { getMarkdown } from '@milkdown/kit/utils'
 import VisualMarkdownEditor from './VisualMarkdownEditor.vue'
 import { useSettingsStore } from '@/stores/settings'
+import { useThemeStore } from '@/stores/theme'
+import { codeBlockConfig } from '@milkdown/kit/component/code-block'
+import { EditorView as CodeMirror } from '@codemirror/view'
 
 type EditorComponent = { getEditor: () => Editor | undefined }
 
@@ -45,6 +48,20 @@ afterEach(() => {
 })
 
 describe('VisualMarkdownEditor formatting toolbars', () => {
+  it.each(['github-light', 'github-dark'] as const)('keeps Shiki %s mappings after Crepe merges its defaults', async theme => {
+    useThemeStore().codeBlockTheme = theme
+    const wrapper = mount(VisualMarkdownEditor, { props: { initialContent: '```python\nprint("Hello")\n```' }, attachTo: document.body })
+    mounted.push(wrapper)
+    const editor = await waitForEditor(wrapper)
+    const config = editor.action(ctx => ctx.get(codeBlockConfig.key))
+    const matching = config.languages.filter(item => item.alias.includes('python'))
+    expect(matching).toHaveLength(1)
+    const cm = new CodeMirror({ doc: 'print("Hello")', extensions: [...config.extensions, await matching[0]!.load()] })
+    try {
+      const string = [...cm.dom.querySelectorAll<HTMLElement>('.shiki-token')].find(el => el.textContent?.includes('Hello'))
+      expect(string?.style.color.toUpperCase()).toBe(theme === 'github-dark' ? '#9ECBFF' : '#032F62')
+    } finally { cm.destroy() }
+  })
   it('applies bold from the top toolbar to the selected text', async () => {
     const wrapper = mount(VisualMarkdownEditor, { props: { initialContent: 'alpha beta' }, attachTo: document.body })
     mounted.push(wrapper)
diff --git a/frontend/src/features/editor/VisualMarkdownEditor.vue b/frontend/src/features/editor/VisualMarkdownEditor.vue
index 88035a4..7acad31 100644
--- a/frontend/src/features/editor/VisualMarkdownEditor.vue
+++ b/frontend/src/features/editor/VisualMarkdownEditor.vue
@@ -2,7 +2,12 @@
 import { onBeforeUnmount, onMounted, ref, watch } from 'vue'
 import { Link } from '@element-plus/icons-vue'
 import { Crepe } from '@milkdown/crepe'
-import { oneDark } from '@codemirror/theme-one-dark'
+import { codeBlockConfig } from '@milkdown/kit/component/code-block'
+import { basicSetup } from 'codemirror'
+import { keymap } from '@codemirror/view'
+import { indentWithTab } from '@codemirror/commands'
+import { shikiEditorTheme, shikiLanguages } from './shikiCodeMirror'
+import { installLanguagePickerPopover } from './languagePickerPopover'
 import {
   createCodeBlockCommand,
   toggleEmphasisCommand,
@@ -34,6 +39,7 @@ const editorRoot = ref<HTMLElement | null>(null)
 const loading = ref(true)
 const fontSizeInput = ref(16)
 let crepe: Crepe | null = null
+let disposeLanguagePicker: (() => void) | undefined
 
 function applyProofingPreferences() {
   const editable = editorRoot.value?.querySelector<HTMLElement>('.ProseMirror')
@@ -118,7 +124,6 @@ onMounted(async () => {
     featureConfigs: {
       [Crepe.Feature.Placeholder]: { text: t('开始记录你的想法…', 'Start writing your thoughts…') },
       [Crepe.Feature.CodeMirror]: {
-        theme: themeStore.resolvedCodeBlockTheme === 'github-dark' ? oneDark : [],
         previewOnlyByDefault: false,
         searchPlaceholder: t('搜索语言', 'Search languages'),
         noResultText: t('没有匹配的语言', 'No matching language'),
@@ -170,6 +175,13 @@ onMounted(async () => {
       },
     },
   })
+  // Crepe's defaultsDeep merges language arrays and theme extension internals.
+  // Replace both AFTER feature configuration to avoid default grammar collisions.
+  crepe.editor.config(ctx => ctx.update(codeBlockConfig.key, config => ({
+    ...config,
+    languages: shikiLanguages(themeStore.resolvedCodeBlockTheme),
+    extensions: [basicSetup, keymap.of([indentWithTab]), shikiEditorTheme(themeStore.resolvedCodeBlockTheme)],
+  })))
   crepe.editor.use(fontSizeMarkdownPlugin)
   crepe.on((listener) => {
     listener.markdownUpdated((_ctx, markdown, previousMarkdown) => {
@@ -180,13 +192,14 @@ onMounted(async () => {
     })
   })
   await crepe.create()
+  if (editorRoot.value) disposeLanguagePicker = installLanguagePickerPopover(editorRoot.value)
   applyProofingPreferences()
   loading.value = false
 })
 
 watch([() => settingsStore.spellCheck, () => settingsStore.language], applyProofingPreferences)
 
-onBeforeUnmount(() => { void crepe?.destroy() })
+onBeforeUnmount(() => { disposeLanguagePicker?.(); void crepe?.destroy() })
 
 defineExpose({ getEditor: () => crepe?.editor })
 </script>
@@ -288,7 +301,10 @@ defineExpose({ getEditor: () => crepe?.editor })
 .milkdown-host :deep(.ProseMirror p) { font-weight: 400; }
 .milkdown-host :deep(.ProseMirror h1), .milkdown-host :deep(.ProseMirror h2), .milkdown-host :deep(.ProseMirror h3), .milkdown-host :deep(.ProseMirror h4), .milkdown-host :deep(.ProseMirror h5), .milkdown-host :deep(.ProseMirror h6) { font-weight: 700; }
 .milkdown-host :deep(.font-size-marker) { display: none; }
-.milkdown-host :deep(.milkdown-code-block) { overflow: hidden; border: 1px solid var(--color-code-border); border-radius: 6px; background: var(--color-code-background); color: var(--color-code-text); }
+.milkdown-host :deep(.milkdown-code-block) { overflow: visible; border: 1px solid var(--color-code-border); border-radius: 6px; background: var(--color-code-background); color: var(--color-code-text); }
+.milkdown-host :deep(.language-picker[popover]) { position: fixed !important; inset: auto; left: var(--picker-left) !important; top: var(--picker-top) !important; margin: 0; padding: 0; border: 0; overflow: visible; background: transparent; color: var(--color-text-primary); }
+.milkdown-host :deep(.language-picker .language-list) { height: auto; max-height: var(--picker-list-height, 280px); }
+.milkdown-host :deep(.language-picker .list-wrapper) { width: min(260px, calc(100vw - 24px)); border: 1px solid var(--color-border-default); background: var(--color-surface-elevated); box-shadow: var(--shadow-md); }
 .milkdown-host :deep(.milkdown-code-block .cm-editor),
 .milkdown-host :deep(.milkdown-code-block .cm-gutters),
 .milkdown-host :deep(.milkdown-code-block .cm-panel) { background: var(--color-code-background); }
diff --git a/frontend/src/features/editor/languagePickerPopover.ts b/frontend/src/features/editor/languagePickerPopover.ts
new file mode 100644
index 0000000..c8134a8
--- /dev/null
+++ b/frontend/src/features/editor/languagePickerPopover.ts
@@ -0,0 +1,43 @@
+/** Promote Milkdown's menu to the top layer without moving its Vue-owned DOM. */
+export function installLanguagePickerPopover(root: HTMLElement): () => void {
+  const menus = new Set<HTMLElement>()
+  function sync() {
+    root.querySelectorAll<HTMLElement>('.language-picker').forEach(menu => {
+      const trigger = menu.parentElement?.querySelector<HTMLElement>('.language-button')
+      if (!trigger || typeof menu.showPopover !== 'function') return
+      menus.add(menu)
+      menu.setAttribute('popover', 'manual')
+      const search = menu.querySelector<HTMLInputElement>('.search-input')
+      if (search) {
+        search.autocomplete = 'off'
+        search.spellcheck = false
+      }
+      if (trigger.dataset.expanded !== 'true' || !menu.firstElementChild) {
+        if (menu.matches(':popover-open')) menu.hidePopover()
+        return
+      }
+      if (!menu.matches(':popover-open')) menu.showPopover()
+      const anchor = trigger.getBoundingClientRect()
+      const below = window.innerHeight - anchor.bottom - 16
+      const above = anchor.top - 16
+      const placeAbove = below < 240 && above > below
+      const available = Math.max(80, placeAbove ? above : below)
+      menu.style.setProperty('--picker-list-height', `${Math.min(280, Math.max(32, available - 64))}px`)
+      const bounds = menu.getBoundingClientRect()
+      menu.style.setProperty('--picker-left', `${Math.max(12, Math.min(anchor.left, window.innerWidth - bounds.width - 12))}px`)
+      menu.style.setProperty('--picker-top', `${Math.max(12, placeAbove ? anchor.top - bounds.height - 8 : anchor.bottom + 8)}px`)
+    })
+    for (const menu of menus) if (!root.contains(menu)) menus.delete(menu)
+  }
+  const observer = new MutationObserver(sync)
+  observer.observe(root, { childList: true, subtree: true, attributes: true, attributeFilter: ['data-expanded'] })
+  root.addEventListener('scroll', sync, true)
+  window.addEventListener('resize', sync)
+  sync()
+  return () => {
+    observer.disconnect()
+    root.removeEventListener('scroll', sync, true)
+    window.removeEventListener('resize', sync)
+    for (const menu of menus) if (menu.matches(':popover-open')) menu.hidePopover()
+  }
+}
diff --git a/frontend/src/features/editor/shikiCodeMirror.spec.ts b/frontend/src/features/editor/shikiCodeMirror.spec.ts
new file mode 100644
index 0000000..2b0d114
--- /dev/null
+++ b/frontend/src/features/editor/shikiCodeMirror.spec.ts
@@ -0,0 +1,43 @@
+// @vitest-environment happy-dom
+import { afterEach, expect, it } from 'vitest'
+import { Compartment } from '@codemirror/state'
+import { EditorView } from '@codemirror/view'
+import { shikiLanguage, shikiLanguages } from './shikiCodeMirror'
+import { getCodeTokenizer } from '@/utils/markdown'
+
+const editors: EditorView[] = []
+afterEach(() => { editors.splice(0).forEach(view => view.destroy()) })
+
+it.each(['github-light', 'github-dark'] as const)('uses Shiki %s tokens and updates editable content', async theme => {
+  const support = await shikiLanguage('python', theme)
+  const view = new EditorView({ doc: 'print("Hello")', extensions: [support] })
+  editors.push(view)
+  const tokenize = await getCodeTokenizer(theme)
+  const expected = tokenize('print("Hello")', 'python')[0]!.find(token => token.content.includes('Hello'))!
+  const colored = [...view.dom.querySelectorAll<HTMLElement>('.shiki-token')].find(node => node.textContent?.includes('Hello'))!
+  expect(colored).toBeDefined()
+  const sample = document.createElement('span'); sample.style.color = expected.color!
+  expect(colored.style.color).toBe(sample.style.color)
+  view.dispatch({ changes: { from: 0, to: view.state.doc.length, insert: 'def hello():\n    return 42' } })
+  expect(view.state.doc.toString()).toContain('return 42')
+  expect(view.dom.querySelectorAll('.shiki-token').length).toBeGreaterThan(2)
+  expect(view.dom.textContent).toContain('return 42')
+})
+
+it('reconfigures language and theme without modifying the document', async () => {
+  const config = new Compartment()
+  const view = new EditorView({ doc: 'const answer = 42', extensions: [config.of(await shikiLanguage('javascript', 'github-light'))] })
+  editors.push(view)
+  const before = view.dom.querySelector<HTMLElement>('.shiki-token')!.style.color
+  view.dispatch({ effects: config.reconfigure(await shikiLanguage('javascript', 'github-dark')) })
+  expect(view.dom.querySelector<HTMLElement>('.shiki-token')!.style.color).not.toBe(before)
+  expect(view.state.doc.toString()).toBe('const answer = 42')
+  view.dispatch({ effects: config.reconfigure(await shikiLanguage('text', 'github-dark')) })
+  expect(view.state.doc.toString()).toBe('const answer = 42')
+})
+
+it('offers fenced-code aliases and retains the LaTeX selector', () => {
+  const languages = shikiLanguages('github-light')
+  expect(languages.find(item => item.name === 'Python')?.alias).toContain('py')
+  expect(languages.find(item => item.name === 'LaTeX')?.alias).toContain('latex')
+})
diff --git a/frontend/src/features/editor/shikiCodeMirror.ts b/frontend/src/features/editor/shikiCodeMirror.ts
new file mode 100644
index 0000000..02e1081
--- /dev/null
+++ b/frontend/src/features/editor/shikiCodeMirror.ts
@@ -0,0 +1,67 @@
+import { LanguageDescription, LanguageSupport, StreamLanguage } from '@codemirror/language'
+import { Decoration, EditorView, ViewPlugin, type DecorationSet, type ViewUpdate } from '@codemirror/view'
+import { getCodeTokenizer } from '@/utils/markdown'
+
+type CodeTheme = 'github-light' | 'github-dark'
+
+export async function shikiLanguage(language: string, theme: CodeTheme): Promise<LanguageSupport> {
+  const tokenize = await getCodeTokenizer(theme)
+  const highlights = ViewPlugin.fromClass(class {
+    decorations: DecorationSet
+
+    constructor(view: EditorView) { this.decorations = this.highlight(view) }
+
+    update(update: ViewUpdate) {
+      if (update.docChanged) this.decorations = this.highlight(update.view)
+    }
+
+    highlight(view: EditorView): DecorationSet {
+      const tokens = tokenize(view.state.doc.toString(), language)
+      const ranges = tokens.flatMap((line, index) => {
+        let offset = view.state.doc.line(index + 1).from
+        return line.flatMap(token => {
+          const from = offset
+          offset += token.content.length
+          if (from === offset) return []
+          const fontStyle = token.fontStyle ?? 0
+          return [Decoration.mark({
+            class: 'shiki-token',
+            attributes: { style: `color:${token.color};font-style:${fontStyle & 1 ? 'italic' : 'normal'};font-weight:${fontStyle & 2 ? 'bold' : 'normal'};text-decoration:${fontStyle & 4 ? 'underline' : 'none'}` },
+          }).range(from, offset)]
+        })
+      })
+      return Decoration.set(ranges)
+    }
+  }, { decorations: value => value.decorations })
+
+  // CodeMirror still owns selection, input and undo. Shiki owns token colors.
+  const parser = StreamLanguage.define({ token(stream) { stream.skipToEnd(); return null } })
+  return new LanguageSupport(parser, highlights)
+}
+
+export function shikiLanguages(theme: CodeTheme): LanguageDescription[] {
+  return [
+    { name: 'C', alias: ['c'] },
+    { name: 'C++', alias: ['cpp', 'c++'] },
+    { name: 'Python', alias: ['python', 'py'] },
+    { name: 'JavaScript', alias: ['javascript', 'js'] },
+    { name: 'TypeScript', alias: ['typescript', 'ts'] },
+    { name: 'HTML', alias: ['html'] },
+    { name: 'CSS', alias: ['css'] },
+    { name: 'JSON', alias: ['json'] },
+    { name: 'Shell', alias: ['shell', 'bash', 'sh'] },
+    { name: 'SQL', alias: ['sql'] },
+    { name: 'Markdown', alias: ['markdown', 'md'] },
+    { name: 'Plain text', alias: ['text', 'plaintext'] },
+    { name: 'LaTeX', alias: ['latex'] },
+  ].map(({ name, alias }) => LanguageDescription.of({
+    name, alias, load: () => shikiLanguage(alias[0]!, theme),
+  }))
+}
+
+export function shikiEditorTheme(theme: CodeTheme) {
+  return EditorView.theme({
+    '&': { color: 'var(--color-code-text)', backgroundColor: 'var(--color-code-background)' },
+    '.cm-gutters': { color: 'var(--color-code-muted)', backgroundColor: 'var(--color-code-background)' },
+  }, { dark: theme === 'github-dark' })
+}
diff --git a/frontend/src/utils/markdown.ts b/frontend/src/utils/markdown.ts
index 3751939..008c66f 100644
--- a/frontend/src/utils/markdown.ts
+++ b/frontend/src/utils/markdown.ts
@@ -3,6 +3,8 @@ import { marked } from 'marked'
 import { createHighlighterCore } from 'shiki/core'
 import { createJavaScriptRegexEngine } from '@shikijs/engine-javascript'
 import css from '@shikijs/langs/css'
+import c from '@shikijs/langs/c'
+import cpp from '@shikijs/langs/cpp'
 import html from '@shikijs/langs/html'
 import javascript from '@shikijs/langs/javascript'
 import json from '@shikijs/langs/json'
@@ -19,7 +21,7 @@ marked.setOptions({ gfm: true, breaks: true })
 // Highlighter 是昂贵的单例；复用初始化 Promise，避免每个代码块重复加载语法与主题。
 const highlighter = createHighlighterCore({
   themes: [githubLight, githubDark],
-  langs: [markdown, html, css, javascript, typescript, json, python, shell, sql],
+  langs: [markdown, html, css, javascript, typescript, json, python, shell, sql, c, cpp],
   engine: createJavaScriptRegexEngine(),
 })
 
@@ -38,6 +40,18 @@ export async function highlightCode(source: string, requestedLanguage = 'text'):
   })
 }
 
+/** Share the initialized grammar/theme registry with editable code blocks. */
+export async function getCodeTokenizer(theme: 'github-light' | 'github-dark') {
+  const shiki = await highlighter
+  return (source: string, requestedLanguage: string) => {
+    const language = languageAliases[requestedLanguage] ?? requestedLanguage
+    return shiki.codeToTokens(source, {
+      lang: shiki.getLoadedLanguages().includes(language as never) ? language : 'text',
+      theme,
+    }).tokens
+  }
+}
+
 export async function renderMarkdown(source: string): Promise<string> {
   const html = marked.parse(source, { async: false }) as string
   const documentNode = new DOMParser().parseFromString(`<body>${html}</body>`, 'text/html')