diff --git a/vehicle-data-platform/apps/web/src/v2/pages/UsersPage.test.tsx b/vehicle-data-platform/apps/web/src/v2/pages/UsersPage.test.tsx
index c727ebf0..89d215c7 100644
--- a/vehicle-data-platform/apps/web/src/v2/pages/UsersPage.test.tsx
+++ b/vehicle-data-platform/apps/web/src/v2/pages/UsersPage.test.tsx
@@ -169,6 +169,42 @@ test('keeps the customer directory visible on mobile and opens details on demand
   expect(screen.getAllByRole('button', { name: '新建客户账号' })).toHaveLength(1);
 });
 
+test('keeps granted vehicles primary and reveals mobile assignment tools on demand', async () => {
+  layout.mobile = true;
+  const vehicles = Array.from({ length: 5 }, (_, index) => ({
+    vin: `VIN${String(index + 1).padStart(3, '0')}`,
+    plate: `粤A${String(index + 1).padStart(5, '0')}`,
+    validFrom: '2026-06-05T00:00:00+08:00',
+    sourceSystem: 'manual',
+    grantedBy: '平台管理员'
+  }));
+  mocks.adminUsers.mockResolvedValue([{
+    id: 7, username: 'customer-east', displayName: '华东客户', userType: 'customer', status: 'enabled',
+    customerRef: '', tenantRef: '', authProvider: 'local', menuKeys: ['monitor', 'vehicles', 'tracks', 'statistics'],
+    vehicleVins: vehicles.map((vehicle) => vehicle.vin), vehicles, grantHistory: [],
+    createdAt: '2026-07-16T00:00:00Z', updatedAt: '2026-07-16T00:00:00Z'
+  }]);
+  const client = new QueryClient({ defaultOptions: { queries: { retry: false } } });
+  render(<QueryClientProvider client={client}><UsersPage /></QueryClientProvider>);
+
+  fireEvent.click(await screen.findByRole('button', { name: /选择客户 华东客户/ }));
+
+  const toggle = await screen.findByRole('button', { name: '添加授权车辆' });
+  expect(toggle).toHaveAttribute('aria-expanded', 'false');
+  expect(document.querySelector('.v2-user-vehicle-section')).toHaveClass('is-composer-collapsed');
+  expect(screen.queryByRole('textbox', { name: '按车牌或 VIN 搜索' })).not.toBeInTheDocument();
+  expect(screen.getAllByRole('button', { name: /^移除 / })).toHaveLength(4);
+  expect(screen.getByText('第 1–4 条，共 5 辆')).toBeInTheDocument();
+  expect(document.querySelector('.v2-user-editor-last-login')).toHaveTextContent('最近登录');
+
+  fireEvent.click(toggle);
+
+  expect(screen.getByRole('button', { name: '收起添加车辆' })).toHaveAttribute('aria-expanded', 'true');
+  expect(document.querySelector('.v2-user-vehicle-section')).not.toHaveClass('is-composer-collapsed');
+  expect(screen.getByRole('textbox', { name: '按车牌或 VIN 搜索' })).toBeInTheDocument();
+  expect(document.querySelector('#v2-user-vehicle-composer')).toBeInTheDocument();
+});
+
 test('filters the customer directory by status and exposes the active result scope', async () => {
   mocks.adminUsers.mockResolvedValue([
     {
diff --git a/vehicle-data-platform/apps/web/src/v2/pages/UsersPage.tsx b/vehicle-data-platform/apps/web/src/v2/pages/UsersPage.tsx
index 742abdda..21dcc6ff 100644
--- a/vehicle-data-platform/apps/web/src/v2/pages/UsersPage.tsx
+++ b/vehicle-data-platform/apps/web/src/v2/pages/UsersPage.tsx
@@ -94,6 +94,7 @@ export default function UsersPage() {
   const [assignedKeyword, setAssignedKeyword] = useState('');
   const [assignedPage, setAssignedPage] = useState(1);
   const [bulkVINs, setBulkVINs] = useState('');
+  const [vehicleComposerOpen, setVehicleComposerOpen] = useState(false);
   const [vehicleLabels, setVehicleLabels] = useState<Record<string, string>>({});
   const [feedback, setFeedback] = useState('');
   const [editingGrantVIN, setEditingGrantVIN] = useState('');
@@ -103,6 +104,7 @@ export default function UsersPage() {
   const editingGrantPlate = editingGrant ? vehicleLabels[editingGrant.vin] : '';
   const grantWindowInvalid = Boolean(editingGrant && (!editingGrant.validFrom || (editingGrant.validTo && editingGrant.validTo <= editingGrant.validFrom)));
   const editorVisible = creating || Boolean(selected);
+  const vehicleComposerVisible = !mobileLayout || creating || draft.vehicleGrants.length === 0 || vehicleComposerOpen;
   useSideSheetA11y(editorVisible, '.v2-user-editor-sidesheet', 'v2-user-editor-sheet', '客户账号详情', '关闭账号详情');
   useSideSheetA11y(Boolean(editingGrant), '.v2-user-grant-sidesheet', 'v2-user-grant-window', '车辆授权有效期', '关闭车辆授权有效期');
 
@@ -173,6 +175,7 @@ export default function UsersPage() {
     setAssignedKeyword('');
     setAssignedPage(1);
     setBulkVINs('');
+    setVehicleComposerOpen(true);
     setVehicleLabels({});
     setFeedback('');
     setEditingGrantVIN('');
@@ -185,6 +188,7 @@ export default function UsersPage() {
     setAssignedKeyword('');
     setAssignedPage(1);
     setBulkVINs('');
+    setVehicleComposerOpen(false);
     setVehicleLabels({});
     setFeedback('');
     setEditingGrantVIN('');
@@ -198,6 +202,7 @@ export default function UsersPage() {
     setAssignedKeyword('');
     setAssignedPage(1);
     setBulkVINs('');
+    setVehicleComposerOpen(user.vehicles.length === 0);
     setFeedback('');
     setEditingGrantVIN('');
   };
@@ -355,7 +360,7 @@ export default function UsersPage() {
       width={mobileLayout ? '100%' : 'min(840px, 100vw)'}
       aria-label="客户账号详情"
       title={<div className="v2-user-editor-sheet-title">
-        <span><strong>{creating ? '创建客户账号' : selected?.displayName}</strong><small>{creating ? '设置登录身份和最小必要权限' : `@${selected?.username} · ${draft.menuKeys.length} 个菜单 · ${draft.vehicleGrants.length} 辆车 · 最近登录 ${formatTime(selected?.lastLoginAt)}`}</small></span>
+        <span><strong>{creating ? '创建客户账号' : selected?.displayName}</strong><small>{creating ? '设置登录身份和最小必要权限' : <><span>@{selected?.username} · {draft.menuKeys.length} 个菜单 · {draft.vehicleGrants.length} 辆车</span><span className="v2-user-editor-last-login"> · 最近登录 {formatTime(selected?.lastLoginAt)}</span></>}</small></span>
         <label className="v2-user-status"><Switch aria-label={draft.status === 'enabled' ? '账号启用' : '账号停用'} checked={draft.status === 'enabled'} onChange={(checked) => setDraft((value) => ({ ...value, status: checked ? 'enabled' : 'disabled' }))} /><span>{draft.status === 'enabled' ? '账号启用' : '账号停用'}</span></label>
       </div>}
       onCancel={closeEditor}
@@ -382,19 +387,42 @@ export default function UsersPage() {
           </Card>
           </Tabs.TabPane>
           <Tabs.TabPane tab={<span className="v2-user-tab-label">车辆权限<Tag color={draft.vehicleGrants.length ? 'blue' : 'grey'} type="light" size="small">{draft.vehicleGrants.length}</Tag></span>} itemKey="vehicles">
-          <Card className="v2-user-editor-section v2-user-vehicle-section" title={<span className="v2-user-section-title">车辆权限与有效期 <Tag color={draft.vehicleGrants.length ? 'blue' : 'grey'} type="light" size="small">{draft.vehicleGrants.length} 辆</Tag></span>} headerLine headerExtraContent={draft.vehicleGrants.length ? <Button theme="borderless" type="tertiary" size="small" onClick={() => setDraft((value) => ({ ...value, vehicleGrants: [] }))}>清空</Button> : null}>
-            <div className="v2-vehicle-permission-tools"><label><span>按车牌或 VIN 搜索</span><Input aria-label="按车牌或 VIN 搜索" value={vehicleKeyword} onChange={setVehicleKeyword} placeholder="输入后显示候选车辆" /></label><label><span>批量粘贴 VIN</span><span className="v2-bulk-vin"><Input value={bulkVINs} onChange={setBulkVINs} placeholder="空格、逗号或换行分隔" /><Button theme="light" disabled={!bulkVINs.trim()} onClick={addBulkVINs}>加入</Button></span></label></div>
-            {deferredVehicleKeyword ? <VehicleCandidateList
-              className="v2-vehicle-candidates"
-              layout="grid"
-              items={candidateVehicles}
-              loading={candidates.isPending}
-              error={candidates.isError ? (candidates.error instanceof Error ? candidates.error.message : '车辆候选加载失败') : undefined}
-              onRetry={() => candidates.refetch()}
-              selectedVins={assigned}
-              selectedLabel="已分配"
-              onSelect={(vehicle) => toggleVIN(vehicle.vin)}
-            /> : null}
+          <Card
+            className={`v2-user-editor-section v2-user-vehicle-section${mobileLayout && !vehicleComposerVisible ? ' is-composer-collapsed' : ''}`}
+            title={<span className="v2-user-section-title">车辆权限与有效期 <Tag color={draft.vehicleGrants.length ? 'blue' : 'grey'} type="light" size="small">{draft.vehicleGrants.length} 辆</Tag></span>}
+            headerLine
+            headerExtraContent={draft.vehicleGrants.length ? <div className="v2-user-section-actions">
+              {mobileLayout && draft.vehicleGrants.length ? <Button
+                className="v2-user-vehicle-tools-toggle"
+                theme="light"
+                type="primary"
+                size="small"
+                icon={!vehicleComposerOpen ? <IconPlus /> : undefined}
+                aria-controls="v2-user-vehicle-composer"
+                aria-expanded={vehicleComposerOpen}
+                aria-label={vehicleComposerOpen ? '收起添加车辆' : '添加授权车辆'}
+                onClick={() => setVehicleComposerOpen((value) => !value)}
+              >{vehicleComposerOpen ? '收起' : '添加'}</Button> : null}
+              {draft.vehicleGrants.length ? <Button theme="borderless" type="tertiary" size="small" onClick={() => {
+                setDraft((value) => ({ ...value, vehicleGrants: [] }));
+                setVehicleComposerOpen(true);
+              }}>清空</Button> : null}
+            </div> : null}
+          >
+            {vehicleComposerVisible ? <div id="v2-user-vehicle-composer" className="v2-user-vehicle-composer">
+              <div className="v2-vehicle-permission-tools"><label><span>按车牌或 VIN 搜索</span><Input aria-label="按车牌或 VIN 搜索" value={vehicleKeyword} onChange={setVehicleKeyword} placeholder="输入后显示候选车辆" /></label><label><span>批量粘贴 VIN</span><span className="v2-bulk-vin"><Input value={bulkVINs} onChange={setBulkVINs} placeholder="空格、逗号或换行分隔" /><Button theme="light" disabled={!bulkVINs.trim()} onClick={addBulkVINs}>加入</Button></span></label></div>
+              {deferredVehicleKeyword ? <VehicleCandidateList
+                className="v2-vehicle-candidates"
+                layout="grid"
+                items={candidateVehicles}
+                loading={candidates.isPending}
+                error={candidates.isError ? (candidates.error instanceof Error ? candidates.error.message : '车辆候选加载失败') : undefined}
+                onRetry={() => candidates.refetch()}
+                selectedVins={assigned}
+                selectedLabel="已分配"
+                onSelect={(vehicle) => toggleVIN(vehicle.vin)}
+              /> : null}
+            </div> : null}
             {draft.vehicleGrants.length ? <>
               <div className="v2-assigned-toolbar">
                 <span><strong>已授权车辆</strong><small>{assignedKeyword ? `${filteredAssignedGrants.length} 条匹配结果` : `${draft.vehicleGrants.length} 辆车拥有当前访问权限`}</small></span>
diff --git a/vehicle-data-platform/apps/web/src/v2/productionEntry.test.ts b/vehicle-data-platform/apps/web/src/v2/productionEntry.test.ts
index b67f3eb6..e2cead77 100644
--- a/vehicle-data-platform/apps/web/src/v2/productionEntry.test.ts
+++ b/vehicle-data-platform/apps/web/src/v2/productionEntry.test.ts
@@ -237,7 +237,8 @@ describe('V2 production entry', () => {
     expect(corePageSources.UsersPage).toContain("'关闭账号详情'");
     expect(corePageSources.UsersPage).toContain('<Card className="v2-user-editor-section v2-user-identity-section"');
     expect(corePageSources.UsersPage).toContain('<Card className="v2-user-editor-section v2-user-menu-section"');
-    expect(corePageSources.UsersPage).toContain('<Card className="v2-user-editor-section v2-user-vehicle-section"');
+    expect(corePageSources.UsersPage).toContain('v2-user-editor-section v2-user-vehicle-section');
+    expect(corePageSources.UsersPage).toContain('id="v2-user-vehicle-composer"');
     expect(corePageSources.UsersPage).toContain('<PanelEmpty className="v2-user-list-empty"');
     expect(corePageSources.UsersPage).not.toContain('className="v2-user-editor-empty"');
     expect(corePageSources.UsersPage).toContain('<Empty className="v2-user-vehicle-empty"');
diff --git a/vehicle-data-platform/apps/web/src/v2/styles/workspace.css b/vehicle-data-platform/apps/web/src/v2/styles/workspace.css
index 63785735..da3428ca 100644
--- a/vehicle-data-platform/apps/web/src/v2/styles/workspace.css
+++ b/vehicle-data-platform/apps/web/src/v2/styles/workspace.css
@@ -9163,6 +9163,8 @@
 }
 
 .v2-user-editor-sheet-title small {
+  display: flex;
+  min-width: 0;
   overflow: hidden;
   color: #7b899a;
   font-size: 10px;
@@ -9172,6 +9174,14 @@
   white-space: nowrap;
 }
 
+.v2-user-editor-sheet-title small > span {
+  min-width: 0;
+}
+
+.v2-user-editor-last-login {
+  flex: 0 0 auto;
+}
+
 .v2-user-editor-sheet-title .v2-user-status {
   display: flex;
   min-width: 92px;
@@ -9248,6 +9258,17 @@
   box-shadow: 0 6px 22px rgba(31, 53, 80, .05);
 }
 
+.v2-user-section-actions {
+  display: flex;
+  align-items: center;
+  gap: 4px;
+}
+
+.v2-user-vehicle-composer {
+  display: grid;
+  gap: 10px;
+}
+
 .v2-user-editor-sidesheet .semi-sidesheet-footer {
   min-height: 64px;
   border-top: 1px solid #e2e9f1;
@@ -9325,6 +9346,10 @@
     font-size: 9px;
   }
 
+  .v2-user-editor-last-login {
+    display: none;
+  }
+
   .v2-user-editor-sheet-title .v2-user-status {
     min-width: 34px;
   }
@@ -9358,6 +9383,54 @@
     -webkit-overflow-scrolling: touch;
   }
 
+  .v2-user-section-actions > .semi-button {
+    min-width: 0;
+    min-height: 32px;
+    border-radius: 7px;
+    padding-inline: 8px;
+    font-size: 9px;
+  }
+
+  .v2-user-vehicle-tools-toggle.semi-button {
+    min-width: 58px;
+  }
+
+  .v2-user-vehicle-composer {
+    gap: 8px;
+  }
+
+  .v2-user-editor-sidesheet .v2-vehicle-permission-tools {
+    gap: 8px;
+  }
+
+  .v2-user-vehicle-section.is-composer-collapsed .v2-assigned-toolbar {
+    margin-top: 0;
+    border-top: 0;
+    padding-top: 1px;
+  }
+
+  .v2-user-editor-sidesheet .v2-assigned-toolbar {
+    grid-template-columns: 104px minmax(0, 1fr);
+    align-items: end;
+    gap: 8px;
+  }
+
+  .v2-user-editor-sidesheet .v2-assigned-toolbar > .semi-input-wrapper {
+    min-height: 40px;
+  }
+
+  .v2-user-editor-sidesheet .v2-assigned-vins > .v2-assigned-vehicle-card.semi-card {
+    min-height: 90px;
+    padding: 9px 10px;
+    contain-intrinsic-size: auto 90px;
+  }
+
+  .v2-user-editor-sidesheet .v2-assigned-vehicle-card > .semi-card-body > .v2-assigned-vehicle-interval {
+    gap: 6px;
+    margin-top: 7px;
+    padding-top: 6px;
+  }
+
   .v2-user-editor-sidesheet .v2-user-editor-tabs > .semi-tabs-content::-webkit-scrollbar {
     width: 11px;
   }