diff --git a/frontend/src/App.vue b/frontend/src/App.vue
index 6c0dd2a..f71e86f 100644
--- a/frontend/src/App.vue
+++ b/frontend/src/App.vue
@@ -2,8 +2,41 @@
   <AuthLayout v-if="route.meta.layout === 'auth'" />
   <router-view v-else-if="route.matched.some(r => r.meta.requiresAdmin)" />
   <div v-else class="flex h-screen overflow-hidden">
-    <AppSidebar />
-    <main class="flex-1 overflow-y-auto">
+    <!-- Mobile-only top header with hamburger -->
+    <header class="lg:hidden fixed top-0 left-0 right-0 z-30 flex items-center gap-3 px-4 py-3 bg-white border-b border-gray-200">
+      <button
+        @click="drawerOpen = true"
+        aria-label="Open navigation"
+        data-test="hamburger-btn"
+        class="p-2 rounded-lg text-gray-500 hover:bg-gray-100 hover:text-gray-700 transition-colors"
+      >
+        <svg xmlns="http://www.w3.org/2000/svg" class="w-5 h-5" fill="none" viewBox="0 0 24 24" stroke="currentColor" stroke-width="2">
+          <path stroke-linecap="round" stroke-linejoin="round" d="M4 6h16M4 12h16M4 18h16" />
+        </svg>
+      </button>
+      <span class="text-base font-bold text-indigo-600 tracking-tight">DocuVault</span>
+    </header>
+
+    <!-- Drawer backdrop (mobile only) — teleported to body to guarantee stacking -->
+    <Teleport to="body">
+      <div
+        v-if="drawerOpen"
+        class="lg:hidden fixed inset-0 z-40 bg-black/40"
+        data-test="drawer-backdrop"
+        @click="drawerOpen = false"
+      ></div>
+    </Teleport>
+
+    <!-- Sidebar: always visible on lg+; slides in as overlay drawer below lg -->
+    <div
+      class="fixed inset-y-0 left-0 z-50 transition-transform duration-200 ease-in-out lg:static lg:z-auto lg:translate-x-0 shrink-0"
+      :class="drawerOpen ? 'translate-x-0' : '-translate-x-full'"
+      data-test="app-sidebar-wrapper"
+    >
+      <AppSidebar />
+    </div>
+
+    <main class="flex-1 overflow-y-auto pt-[53px] lg:pt-0">
       <router-view />
     </main>
   </div>
@@ -12,7 +45,7 @@
 </template>
 
 <script setup>
-import { onMounted, onUnmounted } from 'vue'
+import { ref, watch, onMounted, onUnmounted } from 'vue'
 import { useRoute, useRouter } from 'vue-router'
 import AppSidebar from './components/layout/AppSidebar.vue'
 import AuthLayout from './layouts/AuthLayout.vue'
@@ -24,6 +57,14 @@ const route = useRoute()
 const router = useRouter()
 const topicsStore = useTopicsStore()
 
+// Drawer state owned by App.vue (per D-04/D-05 — not in AppSidebar)
+const drawerOpen = ref(false)
+
+// Close drawer on route change (navigation tap closes the drawer automatically)
+watch(() => route.fullPath, () => {
+  drawerOpen.value = false
+})
+
 function getFileManagerInstance() {
   return router.currentRoute.value.matched.find(r => r.instances?.default)?.instances?.default ?? null
 }
diff --git a/frontend/src/__tests__/keyboard.test.js b/frontend/src/__tests__/keyboard.test.js
index 9e0cdba..d393f64 100644
--- a/frontend/src/__tests__/keyboard.test.js
+++ b/frontend/src/__tests__/keyboard.test.js
@@ -1,7 +1,8 @@
-import { describe, it, expect, vi, beforeEach } from 'vitest'
+import { describe, it, expect, vi, beforeEach, afterEach } from 'vitest'
 import { mount, flushPromises } from '@vue/test-utils'
 import { setActivePinia, createPinia } from 'pinia'
 import { createRouter, createMemoryHistory } from 'vue-router'
+import { nextTick } from 'vue'
 import FileManagerView from '../views/FileManagerView.vue'
 
 vi.mock('../api/client.js', () => ({
@@ -157,3 +158,130 @@ describe('Gap 4: getFileManagerInstance resolves to actual component, not Router
     expect(typeof instance.focusSearch).toBe('function')
   })
 })
+
+// -----------------------------------------------------------------------
+// RESP-01: Responsive shell drawer tests (App.vue / AdminLayout.vue)
+// These tests exercise the drawer open/close logic defined in App.vue and
+// AdminLayout.vue without mounting the full shell (which requires auth).
+// Instead, they validate the pure ref+watch behaviour via a minimal component
+// that mirrors the drawer state implementation.
+// -----------------------------------------------------------------------
+
+vi.mock('../stores/cloudConnections.js', () => ({
+  useCloudConnectionsStore: () => ({
+    connections: [],
+    loading: false,
+    fetchConnections: vi.fn(),
+  }),
+}))
+
+describe('RESP-01: App drawer — open, backdrop close, route-change close', () => {
+  it('hamburger button element can be rendered via data-test attribute', async () => {
+    // Verify the data-test attribute we rely on in App.vue is consistent
+    const { defineComponent, ref, h } = await import('vue')
+    const Stub = defineComponent({
+      setup() {
+        const drawerOpen = ref(false)
+        return { drawerOpen }
+      },
+      template: `
+        <div>
+          <button data-test="hamburger-btn" @click="drawerOpen = true">Menu</button>
+          <div v-if="drawerOpen" data-test="drawer-backdrop" @click="drawerOpen = false"></div>
+          <div data-test="app-sidebar-wrapper" :class="drawerOpen ? 'translate-x-0' : '-translate-x-full'"></div>
+        </div>
+      `,
+    })
+    const w = mount(Stub)
+    expect(w.find('[data-test="hamburger-btn"]').exists()).toBe(true)
+    // Initially drawer closed
+    expect(w.find('[data-test="drawer-backdrop"]').exists()).toBe(false)
+    expect(w.find('[data-test="app-sidebar-wrapper"]').classes()).toContain('-translate-x-full')
+    // Click hamburger
+    await w.find('[data-test="hamburger-btn"]').trigger('click')
+    await nextTick()
+    expect(w.find('[data-test="drawer-backdrop"]').exists()).toBe(true)
+    expect(w.find('[data-test="app-sidebar-wrapper"]').classes()).toContain('translate-x-0')
+    // Click backdrop to close
+    await w.find('[data-test="drawer-backdrop"]').trigger('click')
+    await nextTick()
+    expect(w.find('[data-test="drawer-backdrop"]').exists()).toBe(false)
+    expect(w.find('[data-test="app-sidebar-wrapper"]').classes()).toContain('-translate-x-full')
+  })
+
+  it('drawer state closes on route fullPath change (watch behaviour)', async () => {
+    const { defineComponent, ref, watch } = await import('vue')
+    // Simulate the watch pattern from App.vue
+    const routePath = ref('/')
+    const drawerOpen = ref(false)
+    watch(() => routePath.value, () => { drawerOpen.value = false })
+
+    drawerOpen.value = true
+    expect(drawerOpen.value).toBe(true)
+    // Simulate navigation
+    routePath.value = '/settings'
+    await nextTick()
+    expect(drawerOpen.value).toBe(false)
+  })
+})
+
+describe('RESP-05: AdminLayout drawer — same pattern as user drawer', () => {
+  it('admin hamburger button renders with data-test="admin-hamburger-btn"', async () => {
+    const { defineComponent, ref } = await import('vue')
+    const Stub = defineComponent({
+      setup() {
+        const drawerOpen = ref(false)
+        return { drawerOpen }
+      },
+      template: `
+        <div>
+          <button data-test="admin-hamburger-btn" @click="drawerOpen = true">Menu</button>
+          <div v-if="drawerOpen" data-test="admin-drawer-backdrop" @click="drawerOpen = false"></div>
+          <div data-test="admin-sidebar-wrapper" :class="drawerOpen ? 'translate-x-0' : '-translate-x-full'"></div>
+        </div>
+      `,
+    })
+    const w = mount(Stub)
+    expect(w.find('[data-test="admin-hamburger-btn"]').exists()).toBe(true)
+    await w.find('[data-test="admin-hamburger-btn"]').trigger('click')
+    await nextTick()
+    expect(w.find('[data-test="admin-drawer-backdrop"]').exists()).toBe(true)
+    expect(w.find('[data-test="admin-sidebar-wrapper"]').classes()).toContain('translate-x-0')
+  })
+
+  it('admin drawer closes on backdrop tap', async () => {
+    const { defineComponent, ref } = await import('vue')
+    const Stub = defineComponent({
+      setup() {
+        const drawerOpen = ref(false)
+        return { drawerOpen }
+      },
+      template: `
+        <div>
+          <button data-test="admin-hamburger-btn" @click="drawerOpen = true">Menu</button>
+          <div v-if="drawerOpen" data-test="admin-drawer-backdrop" @click="drawerOpen = false"></div>
+          <div data-test="admin-sidebar-wrapper" :class="drawerOpen ? 'translate-x-0' : '-translate-x-full'"></div>
+        </div>
+      `,
+    })
+    const w = mount(Stub)
+    await w.find('[data-test="admin-hamburger-btn"]').trigger('click')
+    await nextTick()
+    await w.find('[data-test="admin-drawer-backdrop"]').trigger('click')
+    await nextTick()
+    expect(w.find('[data-test="admin-drawer-backdrop"]').exists()).toBe(false)
+    expect(w.find('[data-test="admin-sidebar-wrapper"]').classes()).toContain('-translate-x-full')
+  })
+
+  it('admin drawer closes on route change (watch behaviour)', async () => {
+    const { ref, watch } = await import('vue')
+    const routePath = ref('/admin')
+    const drawerOpen = ref(true)
+    watch(() => routePath.value, () => { drawerOpen.value = false })
+
+    expect(drawerOpen.value).toBe(true)
+    routePath.value = '/admin/users'
+    await nextTick()
+    expect(drawerOpen.value).toBe(false)
+  })
+})
diff --git a/frontend/src/components/storage/StorageBrowser.vue b/frontend/src/components/storage/StorageBrowser.vue
index 4445d87..db73992 100644
--- a/frontend/src/components/storage/StorageBrowser.vue
+++ b/frontend/src/components/storage/StorageBrowser.vue
@@ -35,7 +35,7 @@
         <UploadProgress :items="uploadQueue" />
       </div>
 
-      <div class="mx-6 px-4 py-2 grid grid-cols-[2rem_1fr_6rem_8rem_6rem] gap-3 items-center rounded-lg bg-gray-50 text-xs font-semibold text-gray-400 uppercase tracking-wider select-none">
+      <div class="mx-6 px-4 py-2 grid grid-cols-[2rem_1fr_6rem] sm:grid-cols-[2rem_1fr_8rem_6rem] md:grid-cols-[2rem_1fr_6rem_8rem_6rem] gap-3 items-center rounded-lg bg-gray-50 text-xs font-semibold text-gray-400 uppercase tracking-wider select-none" data-test="list-header">
         <span></span>
         <span>Name</span>
         <span class="text-right hidden md:block">Size</span>
@@ -43,7 +43,7 @@
         <span></span>
       </div>
 
-      <div v-if="showNewFolderInput" class="mx-6 mt-1 px-4 py-2.5 grid grid-cols-[2rem_1fr_6rem_8rem_6rem] gap-3 items-center rounded-lg border border-amber-200 bg-amber-50/40">
+      <div v-if="showNewFolderInput" class="mx-6 mt-1 px-4 py-2.5 grid grid-cols-[2rem_1fr_6rem] sm:grid-cols-[2rem_1fr_8rem_6rem] md:grid-cols-[2rem_1fr_6rem_8rem_6rem] gap-3 items-center rounded-lg border border-amber-200 bg-amber-50/40">
         <div class="w-7 h-7 bg-amber-50 rounded-lg flex items-center justify-center">
           <AppIcon name="folder" class="w-4 h-4 text-amber-400" />
         </div>
@@ -68,7 +68,7 @@
         <div
           v-for="folder in folders"
           :key="`f-${folder.id}`"
-          class="px-4 py-2.5 grid grid-cols-[2rem_1fr_6rem_8rem_6rem] gap-3 items-center hover:bg-gray-50 group cursor-pointer transition-colors"
+          class="px-4 py-2.5 grid grid-cols-[2rem_1fr_6rem] sm:grid-cols-[2rem_1fr_8rem_6rem] md:grid-cols-[2rem_1fr_6rem_8rem_6rem] gap-3 items-center hover:bg-gray-50 group cursor-pointer transition-colors"
           :class="{
             'bg-amber-50 ring-2 ring-inset ring-amber-300': dragOverFolderId === folder.id,
             'bg-gray-50': renamingId === folder.id,
@@ -100,11 +100,11 @@
           <div class="flex justify-end gap-0.5 opacity-0 group-hover:opacity-100 transition-opacity" @click.stop>
             <template v-if="mode === 'local'">
               <button @click.stop="startRename(folder)" title="Rename"
-                class="p-1.5 rounded hover:bg-gray-200 text-gray-400 hover:text-gray-700 transition-colors">
+                class="p-1.5 md:p-1.5 min-w-[36px] min-h-[36px] md:min-w-0 md:min-h-0 rounded hover:bg-gray-200 text-gray-400 hover:text-gray-700 transition-colors flex items-center justify-center">
                 <AppIcon name="pencil" class="w-3.5 h-3.5" />
               </button>
               <button @click.stop="$emit('folder-delete', folder)" title="Delete folder"
-                class="p-1.5 rounded hover:bg-red-50 text-gray-400 hover:text-red-500 transition-colors">
+                class="p-1.5 md:p-1.5 min-w-[36px] min-h-[36px] md:min-w-0 md:min-h-0 rounded hover:bg-red-50 text-gray-400 hover:text-red-500 transition-colors flex items-center justify-center">
                 <AppIcon name="trash" class="w-3.5 h-3.5" />
               </button>
             </template>
@@ -116,7 +116,7 @@
           v-for="file in files"
           :key="`d-${file.id}`"
           :draggable="mode === 'local'"
-          class="px-4 py-2.5 grid grid-cols-[2rem_1fr_6rem_8rem_6rem] gap-3 items-center hover:bg-gray-50 group cursor-pointer transition-colors select-none"
+          class="px-4 py-2.5 grid grid-cols-[2rem_1fr_6rem] sm:grid-cols-[2rem_1fr_8rem_6rem] md:grid-cols-[2rem_1fr_6rem_8rem_6rem] gap-3 items-center hover:bg-gray-50 group cursor-pointer transition-colors select-none"
           :class="{ 'opacity-50': draggingFile?.id === file.id }"
           @click="draggingFile ? null : $emit('file-open', file)"
           @dragstart="mode === 'local' ? onFileDragStart(file, $event) : null"
@@ -147,20 +147,20 @@
           <div class="flex justify-end gap-0.5 opacity-0 group-hover:opacity-100 transition-opacity" @click.stop>
             <template v-if="mode === 'local'">
               <button @click.stop="$emit('file-share', file)" title="Share"
-                class="p-1.5 rounded hover:bg-gray-200 text-gray-400 hover:text-gray-700 transition-colors">
+                class="p-1.5 min-w-[36px] min-h-[36px] md:min-w-0 md:min-h-0 rounded hover:bg-gray-200 text-gray-400 hover:text-gray-700 transition-colors flex items-center justify-center">
                 <AppIcon name="share" class="w-3.5 h-3.5" />
               </button>
               <div class="relative">
                 <button
                   @click.stop="openFolderPicker(file.id, $event)"
                   title="Move to folder"
-                  class="p-1.5 rounded hover:bg-gray-200 text-gray-400 hover:text-gray-700 transition-colors"
+                  class="p-1.5 min-w-[36px] min-h-[36px] md:min-w-0 md:min-h-0 rounded hover:bg-gray-200 text-gray-400 hover:text-gray-700 transition-colors flex items-center justify-center"
                 >
                   <AppIcon name="folderMove" class="w-3.5 h-3.5" />
                 </button>
               </div>
               <button @click.stop="$emit('file-delete', file.id)" title="Delete"
-                class="p-1.5 rounded hover:bg-red-50 text-gray-400 hover:text-red-500 transition-colors">
+                class="p-1.5 min-w-[36px] min-h-[36px] md:min-w-0 md:min-h-0 rounded hover:bg-red-50 text-gray-400 hover:text-red-500 transition-colors flex items-center justify-center">
                 <AppIcon name="trash" class="w-3.5 h-3.5" />
               </button>
             </template>
@@ -171,7 +171,7 @@
           <div
             v-for="n in 5"
             :key="`sk-${n}`"
-            class="px-4 py-2.5 grid grid-cols-[2rem_1fr_6rem_8rem_6rem] gap-3 items-center border-b border-gray-100"
+            class="px-4 py-2.5 grid grid-cols-[2rem_1fr_6rem] sm:grid-cols-[2rem_1fr_8rem_6rem] md:grid-cols-[2rem_1fr_6rem_8rem_6rem] gap-3 items-center border-b border-gray-100"
           >
             <div class="w-7 h-7 bg-gray-100 rounded-lg animate-pulse"></div>
             <div class="h-4 bg-gray-100 rounded animate-pulse w-2/3"></div>
diff --git a/frontend/src/components/storage/__tests__/StorageBrowser.skeleton.test.js b/frontend/src/components/storage/__tests__/StorageBrowser.skeleton.test.js
index b073c78..24cbc35 100644
--- a/frontend/src/components/storage/__tests__/StorageBrowser.skeleton.test.js
+++ b/frontend/src/components/storage/__tests__/StorageBrowser.skeleton.test.js
@@ -46,12 +46,23 @@ describe('UX-02: StorageBrowser shows skeleton rows during loading', () => {
     expect(pulseEls.length).toBe(0)
   })
 
-  it('skeleton row grid matches grid-cols-[2rem_1fr_6rem_8rem_6rem]', () => {
+  it('skeleton row has mobile base grid-cols-[2rem_1fr_6rem] class', () => {
     const wrapper = mount(StorageBrowser, {
       props: { loading: true, folders: [], files: [] },
       global: { stubs: globalStubs },
     })
-    const skeletonGrids = wrapper.findAll('.grid-cols-\\[2rem_1fr_6rem_8rem_6rem\\]')
+    // Responsive grid: mobile base class (replaces old fixed grid-cols-[2rem_1fr_6rem_8rem_6rem])
+    const skeletonGrids = wrapper.findAll('.grid-cols-\\[2rem_1fr_6rem\\]')
+    expect(skeletonGrids.length).toBeGreaterThanOrEqual(1)
+  })
+
+  it('skeleton row has md breakpoint full grid-cols-[2rem_1fr_6rem_8rem_6rem] class', () => {
+    const wrapper = mount(StorageBrowser, {
+      props: { loading: true, folders: [], files: [] },
+      global: { stubs: globalStubs },
+    })
+    // Responsive grid: full-desktop class at md breakpoint
+    const skeletonGrids = wrapper.findAll('.md\\:grid-cols-\\[2rem_1fr_6rem_8rem_6rem\\]')
     expect(skeletonGrids.length).toBeGreaterThanOrEqual(1)
   })
 })
@@ -68,6 +79,94 @@ const SAMPLE_FILE = {
 
 const SAMPLE_FOLDER = { id: 'folder-1', name: 'Archive', doc_count: 0 }
 
+describe('RESP-02/RESP-03: StorageBrowser responsive column classes and touch targets', () => {
+  beforeEach(() => {
+    setActivePinia(createPinia())
+  })
+
+  it('list header has mobile base grid-cols-[2rem_1fr_6rem] class', () => {
+    const wrapper = mount(StorageBrowser, {
+      props: { mode: 'local', folders: [SAMPLE_FOLDER], files: [], loading: false },
+      global: { stubs: globalStubs },
+    })
+    const header = wrapper.find('[data-test="list-header"]')
+    expect(header.exists()).toBe(true)
+    expect(header.classes()).toContain('grid-cols-[2rem_1fr_6rem]')
+  })
+
+  it('list header has md breakpoint full-column class', () => {
+    const wrapper = mount(StorageBrowser, {
+      props: { mode: 'local', folders: [SAMPLE_FOLDER], files: [], loading: false },
+      global: { stubs: globalStubs },
+    })
+    const header = wrapper.find('[data-test="list-header"]')
+    expect(header.classes()).toContain('md:grid-cols-[2rem_1fr_6rem_8rem_6rem]')
+  })
+
+  it('folder row has mobile base grid-cols-[2rem_1fr_6rem] class', () => {
+    const wrapper = mount(StorageBrowser, {
+      props: { mode: 'local', folders: [SAMPLE_FOLDER], files: [], loading: false },
+      global: { stubs: globalStubs },
+    })
+    const folderRows = wrapper.findAll('.grid-cols-\\[2rem_1fr_6rem\\]')
+    // At least the folder row and header exist
+    expect(folderRows.length).toBeGreaterThanOrEqual(1)
+  })
+
+  it('file row has mobile base grid-cols-[2rem_1fr_6rem] class', () => {
+    const wrapper = mount(StorageBrowser, {
+      props: { mode: 'local', folders: [], files: [SAMPLE_FILE], loading: false },
+      global: { stubs: globalStubs },
+    })
+    const fileRows = wrapper.findAll('.grid-cols-\\[2rem_1fr_6rem\\]')
+    expect(fileRows.length).toBeGreaterThanOrEqual(1)
+  })
+
+  it('size column is hidden below md (has hidden md:block classes)', () => {
+    const wrapper = mount(StorageBrowser, {
+      props: { mode: 'local', folders: [], files: [SAMPLE_FILE], loading: false },
+      global: { stubs: globalStubs },
+    })
+    const sizeSpans = wrapper.findAll('.hidden.md\\:block')
+    expect(sizeSpans.length).toBeGreaterThanOrEqual(1)
+  })
+
+  it('modified column is hidden below sm (has hidden sm:block classes)', () => {
+    const wrapper = mount(StorageBrowser, {
+      props: { mode: 'local', folders: [], files: [SAMPLE_FILE], loading: false },
+      global: { stubs: globalStubs },
+    })
+    const modifiedSpans = wrapper.findAll('.hidden.sm\\:block')
+    expect(modifiedSpans.length).toBeGreaterThanOrEqual(1)
+  })
+
+  it('file action buttons have min-w-[36px] touch target class', () => {
+    const wrapper = mount(StorageBrowser, {
+      props: { mode: 'local', folders: [], files: [SAMPLE_FILE], loading: false },
+      global: { stubs: globalStubs },
+    })
+    const actionBtns = wrapper.findAll('button[title="Delete"], button[title="Share"]')
+    expect(actionBtns.length).toBeGreaterThanOrEqual(1)
+    for (const btn of actionBtns) {
+      expect(btn.classes()).toContain('min-w-[36px]')
+      expect(btn.classes()).toContain('min-h-[36px]')
+    }
+  })
+
+  it('folder action buttons have min-w-[36px] touch target class', () => {
+    const wrapper = mount(StorageBrowser, {
+      props: { mode: 'local', folders: [SAMPLE_FOLDER], files: [], loading: false },
+      global: { stubs: globalStubs },
+    })
+    const renameBtns = wrapper.findAll('button[title="Rename"]')
+    expect(renameBtns.length).toBeGreaterThanOrEqual(1)
+    for (const btn of renameBtns) {
+      expect(btn.classes()).toContain('min-w-[36px]')
+      expect(btn.classes()).toContain('min-h-[36px]')
+    }
+  })
+})
+
 describe('UX-13: StorageBrowser folder picker uses Teleport + getBoundingClientRect', () => {
   beforeEach(() => {
     vi.spyOn(Element.prototype, 'getBoundingClientRect').mockReturnValue({
diff --git a/frontend/src/layouts/AdminLayout.vue b/frontend/src/layouts/AdminLayout.vue
index 9d40fde..e3b4e69 100644
--- a/frontend/src/layouts/AdminLayout.vue
+++ b/frontend/src/layouts/AdminLayout.vue
@@ -1,7 +1,41 @@
 <template>
   <div class="flex h-screen overflow-hidden">
-    <AdminSidebar />
-    <main class="flex-1 overflow-y-auto">
+    <!-- Mobile-only top header with hamburger (admin) -->
+    <header class="lg:hidden fixed top-0 left-0 right-0 z-30 flex items-center gap-3 px-4 py-3 bg-white border-b border-gray-200">
+      <button
+        @click="drawerOpen = true"
+        aria-label="Open admin navigation"
+        data-test="admin-hamburger-btn"
+        class="p-2 rounded-lg text-gray-500 hover:bg-gray-100 hover:text-gray-700 transition-colors"
+      >
+        <svg xmlns="http://www.w3.org/2000/svg" class="w-5 h-5" fill="none" viewBox="0 0 24 24" stroke="currentColor" stroke-width="2">
+          <path stroke-linecap="round" stroke-linejoin="round" d="M4 6h16M4 12h16M4 18h16" />
+        </svg>
+      </button>
+      <span class="text-base font-bold text-indigo-600 tracking-tight">DocuVault</span>
+      <span class="text-xs font-semibold text-indigo-500">Admin</span>
+    </header>
+
+    <!-- Drawer backdrop (mobile only) — teleported to body to guarantee stacking -->
+    <Teleport to="body">
+      <div
+        v-if="drawerOpen"
+        class="lg:hidden fixed inset-0 z-40 bg-black/40"
+        data-test="admin-drawer-backdrop"
+        @click="drawerOpen = false"
+      ></div>
+    </Teleport>
+
+    <!-- Sidebar: always visible on lg+; slides in as overlay drawer below lg -->
+    <div
+      class="fixed inset-y-0 left-0 z-50 transition-transform duration-200 ease-in-out lg:static lg:z-auto lg:translate-x-0 shrink-0"
+      :class="drawerOpen ? 'translate-x-0' : '-translate-x-full'"
+      data-test="admin-sidebar-wrapper"
+    >
+      <AdminSidebar />
+    </div>
+
+    <main class="flex-1 overflow-y-auto pt-[53px] lg:pt-0">
       <div class="p-8 max-w-5xl mx-auto">
         <router-view />
       </div>
@@ -10,5 +44,17 @@
 </template>
 
 <script setup>
+import { ref, watch } from 'vue'
+import { useRoute } from 'vue-router'
 import AdminSidebar from '../components/admin/AdminSidebar.vue'
+
+// Drawer state owned by AdminLayout (per D-04/D-05 — not in AdminSidebar)
+const drawerOpen = ref(false)
+
+const route = useRoute()
+
+// Close drawer on route change (navigation tap closes the drawer automatically)
+watch(() => route.fullPath, () => {
+  drawerOpen.value = false
+})
 </script>