diff --git a/admin-frontend-vue/src/layout/AdminLayout.vue b/admin-frontend-vue/src/layout/AdminLayout.vue
index 734f1f17..4d361049 100644
--- a/admin-frontend-vue/src/layout/AdminLayout.vue
+++ b/admin-frontend-vue/src/layout/AdminLayout.vue
@@ -15,7 +15,7 @@ const collapsed = ref(false)
 const activePath = computed(() => route.path)
 const menuEntries = computed(() => toSidebarEntries(session.menuTree))
 const openedKeys = computed(() => groupKeysForActive(menuEntries.value, route.path))
-const pageTitle = computed(() => pageTitleOf(route.meta.title as string | undefined))
+const pageTitle = computed(() => pageTitleOf(route.meta.title))
 const userVm = computed(() => topbarUserOf(session.user))
 const logoUrl = joinAdminPath('assets', 'logo.jpg')
 
diff --git a/admin-frontend-vue/src/router/index.ts b/admin-frontend-vue/src/router/index.ts
index 758ee485..d20f84ce 100644
--- a/admin-frontend-vue/src/router/index.ts
+++ b/admin-frontend-vue/src/router/index.ts
@@ -29,7 +29,7 @@ router.beforeEach(async (to) => {
   if (to.path === '/') {
     return session.firstVisible || true
   }
-  const menuKey = to.meta.menuKey as string | undefined
+  const menuKey = to.meta.menuKey
   if (menuKey && !session.isSuperAdmin && !hasMenu(session.menuTree, menuKey)) {
     // 无权限页面：回退到首个可见页面；一个都没有则回根路由空态。
     return session.firstVisible || '/'
diff --git a/admin-frontend-vue/src/router/meta.ts b/admin-frontend-vue/src/router/meta.ts
new file mode 100644
index 00000000..b1304ec5
--- /dev/null
+++ b/admin-frontend-vue/src/router/meta.ts
@@ -0,0 +1,34 @@
+/** 路由 meta 菜单 key 约定（任务 9）：menuKey 对应后端菜单节点 key，仅作页面级鉴权。 */
+export const ADMIN_MENU_KEY_PATTERN = /^[a-z][a-z0-9_]*$/
+
+/** 从 route.meta 读取菜单 key；缺省/非法类型回退空串（无菜单约束）。 */
+export function metaMenuKey(meta: { menuKey?: unknown } | undefined): string {
+  const value = meta?.menuKey
+  return typeof value === 'string' ? value : ''
+}
+
+/** 菜单 key 是否合规（小写下划线命名）。 */
+export function isValidMenuKey(key: string): boolean {
+  return ADMIN_MENU_KEY_PATTERN.test(key)
+}
+
+export interface MenuKeyCandidate {
+  path?: string
+  menuKey?: unknown
+}
+
+/** 校验一批页面注册的 menuKey：重复与命名格式问题返回可操作清单。 */
+export function validateRouteMenuKeys(records: MenuKeyCandidate[]): string[] {
+  const issues: string[] = []
+  const seen = new Set<string>()
+  for (const record of records) {
+    const key = metaMenuKey(record)
+    if (!key) continue
+    if (seen.has(key)) issues.push(`菜单 key 重复: ${key}`)
+    seen.add(key)
+    if (!isValidMenuKey(key)) {
+      issues.push(`菜单 key 命名非法(须小写下划线): ${record.path || '(无路径)'} -> ${key}`)
+    }
+  }
+  return issues
+}
diff --git a/admin-frontend-vue/src/types/vue-router.d.ts b/admin-frontend-vue/src/types/vue-router.d.ts
new file mode 100644
index 00000000..060c45a5
--- /dev/null
+++ b/admin-frontend-vue/src/types/vue-router.d.ts
@@ -0,0 +1,10 @@
+import 'vue-router'
+
+declare module 'vue-router' {
+  interface RouteMeta {
+    /** 页面标题，驱动顶栏与 document.title。 */
+    title?: string
+    /** 菜单 key（对应后端菜单节点 key）；仅页面级鉴权使用。 */
+    menuKey?: string
+  }
+}
diff --git a/admin-frontend-vue/tests/task-9.test.ts b/admin-frontend-vue/tests/task-9.test.ts
new file mode 100644
index 00000000..a8d30830
--- /dev/null
+++ b/admin-frontend-vue/tests/task-9.test.ts
@@ -0,0 +1,72 @@
+import test from 'node:test'
+import assert from 'node:assert/strict'
+import { readSource } from './helpers.ts'
+import {
+  ADMIN_MENU_KEY_PATTERN,
+  isValidMenuKey,
+  metaMenuKey,
+  validateRouteMenuKeys,
+} from '../src/router/meta.ts'
+import { adminPages } from '../src/router/routes.ts'
+
+test('test_task_009_route_menu_key_meta_normal_primary_path', () => {
+  // 正常主路径：合法 menuKey 被识别。
+  assert.equal(metaMenuKey({ menuKey: 'admin_users' }), 'admin_users')
+  assert.equal(isValidMenuKey('admin_users'), true)
+  assert.equal(ADMIN_MENU_KEY_PATTERN.test('admin_users'), true)
+})
+
+test('test_task_009_route_menu_key_meta_normal_variant_input', () => {
+  // 正常变体：另一合法 key（含数字）也能识别。
+  assert.equal(isValidMenuKey('admin_group_manage'), true)
+  assert.equal(isValidMenuKey('asin_center2'), true)
+})
+
+test('test_task_009_route_menu_key_meta_normal_repeated_operation_is_idempotent', () => {
+  // 正常重复：读取与校验幂等。
+  assert.equal(metaMenuKey({ menuKey: 'shop_list' }), metaMenuKey({ menuKey: 'shop_list' }))
+  assert.equal(isValidMenuKey('shop_list'), isValidMenuKey('shop_list'))
+})
+
+test('test_task_009_route_menu_key_meta_boundary_empty_input', () => {
+  // 边界空值：无 meta/无 menuKey 回退空串；空串 key 不参与命名约束。
+  assert.equal(metaMenuKey(undefined), '')
+  assert.equal(metaMenuKey({}), '')
+  assert.equal(metaMenuKey({ menuKey: '' }), '')
+  assert.deepEqual(validateRouteMenuKeys([]), [])
+})
+
+test('test_task_009_route_menu_key_meta_boundary_single_item', () => {
+  // 边界单元素：单条带合法 key 的注册记录无校验问题。
+  assert.deepEqual(validateRouteMenuKeys([{ path: 'a/b', menuKey: 'admin_x' }]), [])
+})
+
+test('test_task_009_route_menu_key_meta_boundary_limit_or_missing_field', () => {
+  // 边界上限/缺字段：重复 key、驼峰/连字符/数字开头 key 均被校验拒绝。
+  const issues = validateRouteMenuKeys([
+    { path: 'a', menuKey: 'dup' },
+    { path: 'b', menuKey: 'dup' },
+    { path: 'c', menuKey: 'CamelKey' },
+    { path: 'd', menuKey: 'kebab-key' },
+    { path: 'e', menuKey: '1digit' },
+  ])
+  assert.ok(issues.some((i) => i.includes('重复')))
+  assert.ok(issues.some((i) => i.includes('命名非法')))
+})
+
+test('test_task_009_route_menu_key_meta_invalid_input_rejected', () => {
+  // 异常输入：非字符串 menuKey 回退空串，不崩溃、不参与校验。
+  assert.equal(metaMenuKey({ menuKey: 123 }), '')
+  assert.equal(metaMenuKey({ menuKey: null }), '')
+  assert.deepEqual(validateRouteMenuKeys([{ path: 'x', menuKey: 1 }, { path: 'y' }]), [])
+})
+
+test('test_task_009_route_menu_key_meta_dependency_failure_returns_actionable_message', () => {
+  // 依赖失败：RouteMeta 已增强类型；守卫使用类型化 meta；注册表 menuKey 全部合规。
+  const dts = readSource('src/types/vue-router.d.ts')
+  assert.match(dts, /interface RouteMeta/)
+  assert.match(dts, /menuKey\?: string/)
+  const router = readSource('src/router/index.ts')
+  assert.equal(router.includes('as string | undefined'), false, 'menuKey 应为类型化访问，禁止 cast')
+  assert.deepEqual(validateRouteMenuKeys(adminPages), [])
+})