SuperstructureJH · Oct 31, 2026 · Oct 31, 2026
diff --git a/docs/STATUS.md b/docs/STATUS.md
@@ -1,3 +1,10 @@
+## 2026-10-31 — 应用会话恢复返回按钮
+
+- 紧凑标题栏根据应用返回动作显示按钮，标题加载后继续显示；菜单保持桌面应用侧栏与移动系统菜单的各自入口。
+- 返回保留发现广场应用分类、应用中心、移动探索三种来源路径。
+- 33 项相关回归、24 组 macOS Electron 隔离渲染/点击检查、前端静态检查及 Client 构建通过。验证数据采用夹具；部署与真实账号安装端验收待执行。
+- 基线 `4cc8f565f`；详细记录见 `docs/verification/app-chat-back-20261031.md`。
+
 ## 2026-10-30 — 订阅首页比例调整
 
 - 页面左右留白自适应为 16–32px，栏目最小宽度由 260px 调整至 320px，并按实际容器宽度收缩；960px 内容窗口呈现两列。

diff --git a/docs/verification/app-chat-back-20261031.md b/docs/verification/app-chat-back-20261031.md
@@ -0,0 +1,22 @@
+# 应用会话返回按钮 — 2026-10-31
+
+## 基线
+
+- 仓库与版本：`dataelement/bisheng:feat/bisheng-work-120-main@4cc8f565fb5bc8bd918973ce74f876e6fd66af26`，通过远端 fetch 核对。
+- 工作目录：`.worktrees/bisheng-app-chat-back-visible`；分支：`codex/app-chat-back-visible`。
+- 本次修改属于 BISHENG 网页应用会话导航。已安装 BISHENG 包版本 `1.2.0-test.2`，应用包内 `@deepseek-ai/dsh-harness-dev-context` 版本 `0.2.1-rc.2`，通过 asar 元数据读取。
+
+## 根因和行为
+
+- 紧凑布局（内容区宽度 ≤1023px）使用 MobileNav。旧逻辑在会话标题加载后隐藏顶栏返回按钮；SideNav 的返回区域同时受 `touch-desktop` 控制，紧凑布局隐藏该区域。侧栏收起时 AppRoot 的宽屏悬浮返回也退出渲染，导致返回入口消失。
+- 标题栏现在根据应用返回动作显示返回按钮，标题加载与历史展开均保持入口可用。沿用已有按钮样式，给长标题预留菜单和返回所需的宽度。
+- 菜单共用同一处理逻辑：桌面切换应用侧栏，移动端打开系统菜单；操作前关闭历史下拉。
+- 返回继续调用现有来源解析：发现广场进入的会话回到 `/square?type=apps`，应用中心进入的会话回到 `/apps`，移动探索回到 `/apps/explore`。
+
+## 验证
+
+- 旧代码对照：新增 3 项标题加载/移动端返回测试均失败，已有 12 项通过。
+- 修正后 3 个测试文件、33 项通过。AppRoot 与真实 MobileNav、真实来源解析组合测试覆盖标题加载、侧栏展开/收起、历史展开后的三种来源返回，以及此前菜单、新建和历史下拉行为；探索入口测试使用真实路由验证进入与返回。
+- Client 全量 ESLint、1504 个严格类型文件；Platform 全量 ESLint、620 个严格类型文件；UI/file-viewers ESLint、file-viewers tsc 检查通过。Client 生产构建、i18n 与受影响文件架构检查通过。
+- macOS Electron 隔离验证使用真实 MobileNav 和生产 CSS，服务与回调采用夹具。390/768/820/920/1000/1023px × 标题加载前后 × 侧栏展开/收起，24 组检查通过：按钮命中区域、与长标题分离、返回回调触发。证据：主工作区 `outputs/app-chat-back-20261031/`。
+- 当前状态为源码修复和本地自动验证完成。测试环境部署、macOS/Windows 已安装客户端真实账号的发现广场进入与返回验收待执行。
diff --git a/src/frontend/client/src/components/Nav/MobileNav.tsx b/src/frontend/client/src/components/Nav/MobileNav.tsx
@@ -31,7 +31,7 @@ type MobileNavProps = {
   onMenuClick?: () => void;
   preferBackButton?: boolean;
   onBack?: () => void;
-  /** 应用内对话：无合并标题时与侧栏并排展示「返回」；有会话标题时返回在侧栏内，顶栏仅抽屉 */
+  /** App surfaces keep their return action available alongside the menu. */
   appSurfaceBackAction?: () => void;
   /** App-surface: opens the app-chat history dropdown (app card + conversation list).
    *  Caret/grey states key off `appHistoryDropdownOpen`; the dropdown itself is rendered
@@ -114,13 +114,15 @@ export default function MobileNav({
     (historyDropdownOpen && !appSurfaceBackAction) ||
     (appHistoryDropdownOpen && Boolean(appSurfaceBackAction));
 
-  /** 应用内对话：有合并标题时顶栏与主站对话一致（左仅抽屉、中标题、右分享+新建）；无标题时保留「菜单+返回」 */
-  const appSurfaceShowBackWithMenu =
-    Boolean(
-      appSurfaceBackAction &&
-        !preferBackButton &&
-        !(showWorkbenchMergedBar && chatMobileHeader),
-    );
+  // App navigation is available throughout conversation-title hydration.
+  const appSurfaceShowBackWithMenu = Boolean(appSurfaceBackAction) && preferBackButton === false;
+
+  const handleMenuClick = () => {
+    setHistoryDropdownOpen(false);
+    if (appHistoryDropdownOpen) onToggleAppHistoryDropdown?.();
+    if (onMenuClick) onMenuClick();
+    else setSystemMenuOpen(true);
+  };
 
   const appBackBtnClassName =
     'inline-flex size-8 shrink-0 items-center justify-center rounded-lg border border-border-base bg-white text-text-1 shadow-sm transition-colors hover:bg-fill-1';
@@ -141,12 +143,12 @@ export default function MobileNav({
             <button
               type="button"
               data-testid="mobile-header-left-action"
-              aria-label={navVisible ? localize('com_nav_close_sidebar') : localize('com_nav_open_sidebar')}
-              aria-expanded={navVisible}
+              aria-label={localize(onMenuClick && navVisible ? 'com_nav_close_sidebar' : 'com_nav_open_sidebar')}
+              aria-expanded={onMenuClick ? navVisible : undefined}
               className={appBackBtnClassName}
-              onClick={toggleSidebar}
+              onClick={handleMenuClick}
             >
-              {navVisible ? (
+              {onMenuClick && navVisible ? (
                 <X className="size-4" strokeWidth={2} />
               ) : (
                 <Menu className="size-4" strokeWidth={2} />
@@ -172,12 +174,7 @@ export default function MobileNav({
               mobileHeadIconBtnClassName,
               !onMenuClick && (historyDropdownOpen || appHistoryDropdownOpen) && 'pointer-events-none text-text-4',
             )}
-            onClick={preferBackButton ? (onBack ?? toggleSidebar) : () => {
-              setHistoryDropdownOpen(false);
-              if (appHistoryDropdownOpen) onToggleAppHistoryDropdown?.();
-              if (onMenuClick) onMenuClick();
-              else setSystemMenuOpen(true);
-            }}
+            onClick={preferBackButton ? (onBack ?? toggleSidebar) : handleMenuClick}
           >
             {preferBackButton ? (
               <ChevronLeft className="size-4" strokeWidth={2} />
@@ -194,7 +191,10 @@ export default function MobileNav({
                 either edge. max-w reserves room for the menu (left) and the
                 share + new-chat icons (right) so a long title truncates rather
                 than sliding under them. Mirrors the 知识空间 / 订阅 mobile headers. */}
-            <div className="absolute left-1/2 top-0 flex h-full max-w-[calc(100%-128px)] -translate-x-1/2 items-center justify-center px-1">
+            <div className={cn(
+              'absolute left-1/2 top-0 flex h-full -translate-x-1/2 items-center justify-center px-1',
+              appSurfaceShowBackWithMenu ? 'max-w-[calc(100%-176px)]' : 'max-w-[calc(100%-128px)]',
+            )}>
               {appSurfaceBackAction ? (
                 // App-surface chat: title opens the app-chat history dropdown (app card
                 // + conversation list). The dropdown itself is rendered by AppRoot which

diff --git a/src/frontend/client/src/routes/AppRoot.test.tsx b/src/frontend/client/src/routes/AppRoot.test.tsx
@@ -11,10 +11,11 @@ let mockMobile = false;
 let mockCompact = true;
 let mockSidebarVisible = true;
 let mockMerged = true;
+let mockReturnTo = '/square?type=apps';
 const mockHeader = { title: 'New conversation', conversationId: 'old', flowId: 'assistant', flowType: 5, hideShare: true };
 
 jest.mock('react-router-dom', () => ({
-  useLocation: () => ({ pathname: '/app/old/assistant/5', search: '', state: { appSurfaceReturn: '/square?type=apps' } }),
+  useLocation: () => ({ pathname: '/app/old/assistant/5', search: '', state: { appSurfaceReturn: mockReturnTo } }),
   useNavigate: () => mockNavigate,
   useParams: () => ({ fid: 'assistant', type: '5' }),
   Outlet: () => <div>Conversation content</div>,
@@ -61,15 +62,11 @@ jest.mock('~/pages/appChat/components/AppSidebarConvoItem', () => ({
   AppSidebarConvoItem: ({ conv, onClick }: { conv: { title: string }; onClick: () => void }) => <button onClick={onClick}>{conv.title}</button>,
 }));
 jest.mock('~/components/ui/Tooltip2', () => ({ Tooltip: () => null, TooltipProvider: () => null, TooltipTrigger: () => null, TooltipContent: () => null }));
-jest.mock('~/pages/appChat/appChatOrigin', () => ({
-  copyAppChatReturnTo: jest.fn(), copyAppChatOrigin: jest.fn(), normalizeAppChatReturn: (value: string) => value,
-  resolveAppChatExitNavigateTarget: () => '/square?type=apps', writeAppChatReturnTo: jest.fn(),
-}));
 jest.mock('bisheng-icons', () => ({ Outlined: { SidebarMenu: () => null, Plus: () => null, Down: () => null } }));
 
 beforeEach(() => {
   mockMobile = false; mockCompact = true; mockSidebarVisible = true; mockMerged = true;
-  localStorage.clear();
+  localStorage.clear(); sessionStorage.clear(); mockReturnTo = '/square?type=apps';
 });
 
 it.each([true, false])('toggles the compact desktop app sidebar from visibility %s', (visible) => {
@@ -167,3 +164,30 @@ it('retains the app sidebar toggle before a conversation title is available', ()
   fireEvent.click(menu);
   expect(menu).toHaveAttribute('aria-expanded', 'false');
 });
+
+// The compact header owns a visible return action throughout title hydration.
+it.each([true, false])('keeps return available as the title loads with sidebar=%s', (visible) => {
+  mockSidebarVisible = visible;
+  mockMerged = false;
+  const view = render(<AppRoot />);
+  expect(screen.getByRole('button', { name: 'com_ui_go_back' })).toBeVisible();
+  mockMerged = true;
+  view.rerender(<AppRoot />);
+  fireEvent.click(screen.getByRole('button', { name: 'com_ui_go_back' }));
+  expect(mockNavigate).toHaveBeenCalledWith('/square?type=apps', { replace: false });
+});
+
+it('keeps return available on mobile after a title loads', () => {
+  mockMobile = true;
+  render(<AppRoot />);
+  fireEvent.click(screen.getByRole('button', { name: 'com_ui_go_back' }));
+  expect(mockNavigate).toHaveBeenCalledWith('/square?type=apps', { replace: false });
+});
+
+it.each(['/square?type=apps', '/apps', '/apps/explore'])('returns to %s with history expanded', (target) => {
+  mockReturnTo = target;
+  render(<AppRoot />);
+  fireEvent.click(screen.getByRole('button', { name: 'New conversation' }));
+  fireEvent.click(screen.getByRole('button', { name: 'com_ui_go_back' }));
+  expect(mockNavigate).toHaveBeenCalledWith(target, { replace: target === '/apps' });
+});