diff --git a/apps/dsa-web/src/App.test.tsx b/apps/dsa-web/src/App.test.tsx
new file mode 100644
index 000000000..bd0cd2b9f
--- /dev/null
+++ b/apps/dsa-web/src/App.test.tsx
@@ -0,0 +1,161 @@
+import { fireEvent, render, screen } from '@testing-library/react';
+import type { ReactNode } from 'react';
+import { beforeEach, describe, expect, it, vi } from 'vitest';
+import App from './App';
+import * as AuthContext from './contexts/AuthContext';
+
+type AuthState = ReturnType<typeof AuthContext.useAuth>;
+
+const { chatPageShouldThrow, setCurrentRoute, useAgentChatStoreMock } = vi.hoisted(() => {
+  const setCurrentRoute = vi.fn();
+  const chatPageShouldThrow = { value: false };
+  const state = { completionBadge: false };
+  const useAgentChatStoreMock = Object.assign(
+    vi.fn((selector?: (value: typeof state) => unknown) => (selector ? selector(state) : state)),
+    { getState: () => ({ setCurrentRoute }) },
+  );
+  return { chatPageShouldThrow, setCurrentRoute, useAgentChatStoreMock };
+});
+
+vi.mock('./contexts/AuthContext', () => ({
+  AuthProvider: ({ children }: { children: ReactNode }) => children,
+  useAuth: vi.fn(),
+}));
+
+vi.mock('./stores/agentChatStore', () => ({
+  useAgentChatStore: useAgentChatStoreMock,
+}));
+
+vi.mock('./pages/HomePage', () => ({
+  default: () => <div data-testid="home-page">Home</div>,
+}));
+
+vi.mock('./pages/ChatPage', () => ({
+  default: () => {
+    if (chatPageShouldThrow.value) {
+      throw new Error('chunk load failed');
+    }
+    return <div data-testid="chat-page">Chat</div>;
+  },
+}));
+
+vi.mock('./pages/PortfolioPage', () => ({
+  default: () => <div data-testid="portfolio-page">Portfolio</div>,
+}));
+
+vi.mock('./pages/BacktestPage', () => ({
+  default: () => <div data-testid="backtest-page">Backtest</div>,
+}));
+
+vi.mock('./pages/AlertsPage', () => ({
+  default: () => <div data-testid="alerts-page">Alerts</div>,
+}));
+
+vi.mock('./pages/SettingsPage', () => ({
+  default: () => <div data-testid="settings-page">Settings</div>,
+}));
+
+vi.mock('./pages/NotFoundPage', () => ({
+  default: () => <div data-testid="not-found-page">Not Found</div>,
+}));
+
+vi.mock('./pages/LoginPage', () => ({
+  default: () => <div data-testid="login-page">Login</div>,
+}));
+
+function makeAuthState(overrides: Partial<AuthState> = {}): AuthState {
+  return {
+    authEnabled: false,
+    loggedIn: false,
+    passwordSet: false,
+    passwordChangeable: false,
+    setupState: 'no_password',
+    isLoading: false,
+    loadError: null,
+    login: vi.fn().mockResolvedValue({ success: true }),
+    changePassword: vi.fn().mockResolvedValue({ success: true }),
+    logout: vi.fn().mockResolvedValue(undefined),
+    refreshStatus: vi.fn().mockResolvedValue(undefined),
+    ...overrides,
+  };
+}
+
+beforeEach(() => {
+  vi.clearAllMocks();
+  chatPageShouldThrow.value = false;
+  window.history.pushState({}, '', '/');
+  vi.mocked(AuthContext.useAuth).mockReturnValue(makeAuthState());
+});
+
+describe('App routing behavior', () => {
+  it('shows loading fallback while auth status is initializing', () => {
+    vi.mocked(AuthContext.useAuth).mockReturnValue(makeAuthState({ isLoading: true }));
+
+    const { container } = render(<App />);
+
+    expect(container.querySelector('.border-t-cyan')).toBeInTheDocument();
+  });
+
+  it('redirects protected routes to login when auth is enabled but user is not logged in', async () => {
+    vi.mocked(AuthContext.useAuth).mockReturnValue(makeAuthState({
+      authEnabled: true,
+      loggedIn: false,
+      setupState: 'enabled',
+    }));
+    window.history.pushState({}, '', '/portfolio');
+
+    render(<App />);
+
+    expect(await screen.findByTestId('login-page')).toBeInTheDocument();
+    expect(window.location.pathname).toBe('/login');
+    expect(window.location.search).toBe('?redirect=%2Fportfolio');
+  });
+
+  it('renders the current route page after auth is ready', async () => {
+    window.history.pushState({}, '', '/chat');
+
+    render(<App />);
+
+    expect(await screen.findByTestId('chat-page')).toBeInTheDocument();
+    expect(setCurrentRoute).toHaveBeenCalledWith('/chat');
+    expect(screen.queryByTestId('login-page')).not.toBeInTheDocument();
+    expect(screen.queryByTestId('home-page')).not.toBeInTheDocument();
+  });
+
+  it('redirects authenticated login visits back to the home page', async () => {
+    vi.mocked(AuthContext.useAuth).mockReturnValue(makeAuthState({
+      authEnabled: true,
+      loggedIn: true,
+      setupState: 'enabled',
+    }));
+    window.history.pushState({}, '', '/login');
+
+    render(<App />);
+
+    expect(await screen.findByTestId('home-page')).toBeInTheDocument();
+    expect(screen.queryByTestId('login-page')).not.toBeInTheDocument();
+  });
+
+  it('keeps the shell mounted and resets the route boundary after page render errors', async () => {
+    const consoleError = vi.spyOn(console, 'error').mockImplementation(() => undefined);
+    chatPageShouldThrow.value = true;
+    window.history.pushState({}, '', '/chat');
+
+    try {
+      render(<App />);
+
+      expect(await screen.findByRole('heading', { name: '页面加载失败' })).toBeInTheDocument();
+      expect(screen.getByRole('navigation', { name: '主导航' })).toBeInTheDocument();
+      expect(screen.getByRole('button', { name: '重新加载页面' })).toBeInTheDocument();
+      expect(screen.getByRole('button', { name: '返回首页' })).toBeInTheDocument();
+
+      chatPageShouldThrow.value = false;
+      fireEvent.click(screen.getByRole('link', { name: '持仓' }));
+
+      expect(await screen.findByTestId('portfolio-page')).toBeInTheDocument();
+      expect(screen.queryByRole('heading', { name: '页面加载失败' })).not.toBeInTheDocument();
+    } finally {
+      consoleError.mockRestore();
+    }
+  });
+});
diff --git a/apps/dsa-web/src/App.tsx b/apps/dsa-web/src/App.tsx
index 758b97c3e..48a3af24f 100644
--- a/apps/dsa-web/src/App.tsx
+++ b/apps/dsa-web/src/App.tsx
@@ -1,19 +1,25 @@
 import type React from 'react';
-import { useEffect } from 'react';
+import { lazy, useEffect } from 'react';
 import { BrowserRouter as Router, Navigate, Route, Routes, useLocation } from 'react-router-dom';
-import HomePage from './pages/HomePage';
-import BacktestPage from './pages/BacktestPage';
-import SettingsPage from './pages/SettingsPage';
-import LoginPage from './pages/LoginPage';
-import NotFoundPage from './pages/NotFoundPage';
-import ChatPage from './pages/ChatPage';
-import PortfolioPage from './pages/PortfolioPage';
-import AlertsPage from './pages/AlertsPage';
 import { ApiErrorAlert, Shell } from './components/common';
+import {
+  PageLoadingFallback,
+  RouteOutletBoundary,
+  StandaloneRouteBoundary,
+} from './components/layout/RouteBoundary';
 import { AuthProvider, useAuth } from './contexts/AuthContext';
 import { useAgentChatStore } from './stores/agentChatStore';
 import './App.css';
 
+const HomePage = lazy(() => import('./pages/HomePage'));
+const BacktestPage = lazy(() => import('./pages/BacktestPage'));
+const SettingsPage = lazy(() => import('./pages/SettingsPage'));
+const LoginPage = lazy(() => import('./pages/LoginPage'));
+const NotFoundPage = lazy(() => import('./pages/NotFoundPage'));
+const ChatPage = lazy(() => import('./pages/ChatPage'));
+const PortfolioPage = lazy(() => import('./pages/PortfolioPage'));
+const AlertsPage = lazy(() => import('./pages/AlertsPage'));
+
 const AppContent: React.FC = () => {
   const location = useLocation();
   const { authEnabled, loggedIn, isLoading, loadError, refreshStatus } = useAuth();
@@ -23,11 +29,7 @@ const AppContent: React.FC = () => {
   }, [location.pathname]);
 
   if (isLoading) {
-    return (
-      <div className="flex min-h-screen items-center justify-center bg-base">
-        <div className="h-8 w-8 animate-spin rounded-full border-2 border-cyan/20 border-t-cyan" />
-      </div>
-    );
+    return <PageLoadingFallback />;
   }
 
   if (loadError) {
@@ -49,7 +51,11 @@ const AppContent: React.FC = () => {
 
   if (authEnabled && !loggedIn) {
     if (location.pathname === '/login') {
-      return <LoginPage />;
+      return (
+        <StandaloneRouteBoundary>
+          <LoginPage />
+        </StandaloneRouteBoundary>
+      );
     }
     const redirect = encodeURIComponent(location.pathname + location.search);
     return <Navigate to={`/login?redirect=${redirect}`} replace />;
@@ -61,7 +67,13 @@ const AppContent: React.FC = () => {
 
   return (
     <Routes>
-      <Route element={<Shell />}>
+      <Route
+        element={(
+          <Shell>
+            <RouteOutletBoundary />
+          </Shell>
+        )}
+      >
         <Route path="/" element={<HomePage />} />
         <Route path="/chat" element={<ChatPage />} />
         <Route path="/portfolio" element={<PortfolioPage />} />
@@ -70,7 +82,6 @@ const AppContent: React.FC = () => {
         <Route path="/settings" element={<SettingsPage />} />
         <Route path="*" element={<NotFoundPage />} />
       </Route>
-      <Route path="/login" element={<LoginPage />} />
     </Routes>
   );
 };
diff --git a/apps/dsa-web/src/components/layout/RouteBoundary.tsx b/apps/dsa-web/src/components/layout/RouteBoundary.tsx
new file mode 100644
index 000000000..f09a4f8a5
--- /dev/null
+++ b/apps/dsa-web/src/components/layout/RouteBoundary.tsx
@@ -0,0 +1,115 @@
+import type React from 'react';
+import { Component, Suspense } from 'react';
+import type { ErrorInfo } from 'react';
+import { Outlet, useLocation } from 'react-router-dom';
+
+type PageLoadingFallbackProps = {
+  fullPage?: boolean;
+};
+
+export const PageLoadingFallback: React.FC<PageLoadingFallbackProps> = ({ fullPage = true }) => (
+  <div
+    className={
+      fullPage
+        ? 'flex min-h-screen items-center justify-center bg-base'
+        : 'flex min-h-[60vh] items-center justify-center'
+    }
+  >
+    <div className="h-8 w-8 animate-spin rounded-full border-2 border-cyan/20 border-t-cyan" />
+  </div>
+);
+
+type RouteErrorBoundaryProps = {
+  children: React.ReactNode;
+  resetKey: string;
+  fullPage: boolean;
+};
+
+type RouteErrorBoundaryState = {
+  hasError: boolean;
+};
+
+class RouteErrorBoundary extends Component<RouteErrorBoundaryProps, RouteErrorBoundaryState> {
+  override state: RouteErrorBoundaryState = {
+    hasError: false,
+  };
+
+  static getDerivedStateFromError(): RouteErrorBoundaryState {
+    return { hasError: true };
+  }
+
+  override componentDidCatch(error: Error, errorInfo: ErrorInfo) {
+    console.error('Route page failed to render or load', error, errorInfo);
+  }
+
+  override componentDidUpdate(prevProps: RouteErrorBoundaryProps) {
+    if (this.state.hasError && prevProps.resetKey !== this.props.resetKey) {
+      this.setState({ hasError: false });
+    }
+  }
+
+  override render() {
+    if (!this.state.hasError) {
+      return this.props.children;
+    }
+
+    return (
+      <div
+        className={
+          this.props.fullPage
+            ? 'flex min-h-screen items-center justify-center bg-base px-4'
+            : 'flex min-h-[60vh] items-center justify-center px-2 py-8'
+        }
+      >
+        <div className="w-full max-w-md rounded-2xl border border-border bg-card/94 p-6 text-center shadow-soft-card">
+          <h1 className="text-xl font-semibold text-foreground">页面加载失败</h1>
+          <p className="mt-3 text-sm leading-6 text-secondary-text">
+            当前页面资源或组件未能正常加载，可能是网络中断或页面版本已更新。请重新加载页面，或返回首页后再试。
+          </p>
+          <div className="mt-5 flex flex-col gap-3 sm:flex-row sm:justify-center">
+            <button
+              type="button"
+              className="btn-primary"
+              onClick={() => window.location.reload()}
+            >
+              重新加载页面
+            </button>
+            <button
+              type="button"
+              className="rounded-xl border border-border/70 bg-card px-4 py-2 text-sm font-medium text-foreground transition-colors hover:bg-hover"
+              onClick={() => window.location.assign('/')}
+            >
+              返回首页
+            </button>
+          </div>
+        </div>
+      </div>
+    );
+  }
+}
+
+export const RouteBoundary: React.FC<{ children: React.ReactNode; fullPage?: boolean }> = ({
+  children,
+  fullPage = true,
+}) => {
+  const location = useLocation();
+  const resetKey = `${location.pathname}${location.search}`;
+
+  return (
+    <RouteErrorBoundary resetKey={resetKey} fullPage={fullPage}>
+      <Suspense fallback={<PageLoadingFallback fullPage={fullPage} />}>{children}</Suspense>
+    </RouteErrorBoundary>
+  );
+};
+
+export const RouteOutletBoundary: React.FC = () => (
+  <RouteBoundary fullPage={false}>
+    <Outlet />
+  </RouteBoundary>
+);
+
+export const StandaloneRouteBoundary: React.FC<{ children: React.ReactNode }> = ({ children }) => (
+  <RouteBoundary fullPage>
+    {children}
+  </RouteBoundary>
+);
diff --git a/apps/dsa-web/src/components/layout/__tests__/RouteBoundary.test.tsx b/apps/dsa-web/src/components/layout/__tests__/RouteBoundary.test.tsx
new file mode 100644
index 000000000..41cfa6854
--- /dev/null
+++ b/apps/dsa-web/src/components/layout/__tests__/RouteBoundary.test.tsx
@@ -0,0 +1,64 @@
+import { fireEvent, render, screen } from '@testing-library/react';
+import { lazy } from 'react';
+import type React from 'react';
+import { MemoryRouter, Route, Routes } from 'react-router-dom';
+import { describe, expect, it, vi } from 'vitest';
+import { RouteOutletBoundary } from '../RouteBoundary';
+import { Shell } from '../Shell';
+
+vi.mock('../../../contexts/AuthContext', () => ({
+  useAuth: () => ({
+    authEnabled: false,
+    logout: vi.fn().mockResolvedValue(undefined),
+  }),
+}));
+
+vi.mock('../../../stores/agentChatStore', () => {
+  const state = { completionBadge: false };
+
+  return {
+    useAgentChatStore: (selector?: (value: typeof state) => unknown) => (
+      selector ? selector(state) : state
+    ),
+  };
+});
+
+describe('RouteOutletBoundary', () => {
+  it('catches rejected lazy route imports inside the shell and resets on navigation', async () => {
+    const consoleError = vi.spyOn(console, 'error').mockImplementation(() => undefined);
+    const BrokenLazyRoute = lazy(() => (
+      Promise.reject(new Error('chunk load failed')) as Promise<{ default: React.ComponentType }>
+    ));
+
+    try {
+      render(
+        <MemoryRouter initialEntries={['/chat']}>
+          <Routes>
+            <Route
+              element={(
+                <Shell>
+                  <RouteOutletBoundary />
+                </Shell>
+              )}
+            >
+              <Route path="/chat" element={<BrokenLazyRoute />} />
+              <Route path="/portfolio" element={<div data-testid="portfolio-page">Portfolio</div>} />
+            </Route>
+          </Routes>
+        </MemoryRouter>,
+      );
+
+      expect(screen.getByRole('navigation', { name: '主导航' })).toBeInTheDocument();
+      expect(await screen.findByRole('heading', { name: '页面加载失败' })).toBeInTheDocument();
+      expect(screen.getByRole('button', { name: '重新加载页面' })).toBeInTheDocument();
+      expect(screen.getByRole('button', { name: '返回首页' })).toBeInTheDocument();
+
+      fireEvent.click(screen.getByRole('link', { name: '持仓' }));
+
+      expect(await screen.findByTestId('portfolio-page')).toBeInTheDocument();
+      expect(screen.queryByRole('heading', { name: '页面加载失败' })).not.toBeInTheDocument();
+    } finally {
+      consoleError.mockRestore();
+    }
+  });
+});
diff --git a/docs/CHANGELOG.md b/docs/CHANGELOG.md
index d10eee99d..f47933737 100644
--- a/docs/CHANGELOG.md
+++ b/docs/CHANGELOG.md
@@ -11,6 +11,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/).
 
 <!-- 新条目格式：- [类型] 描述（类型取值：新功能/改进/修复/文档/测试/chore）-->
 <!-- 每条独立一行追加到本段末尾，无需分类标题，合并时冲突最小 -->
+- [改进] Web 路由页面改为按需加载，降低首包体积并增加路由加载失败恢复提示。
 
 ## [3.18.0] - 2026-05-21