[Web] Add global Error Boundary with dual-theme support

.Jules/changelog.md

@@ -7,6 +7,7 @@
 ## [Unreleased]
 
 ### Added
+- **Error Boundary:** Added a global `ErrorBoundary` component that catches unexpected errors and displays a friendly, dual-themed fallback UI with a retry action.
 - Inline form validation in Auth page with real-time feedback and proper ARIA accessibility support (`aria-invalid`, `aria-describedby`, `role="alert"`).
 - Dashboard skeleton loading state (`DashboardSkeleton`) to improve perceived performance during data fetch.
 - Comprehensive `EmptyState` component for Groups and Friends pages to better guide new users.

.Jules/knowledge.md

@@ -44,6 +44,20 @@ mobile/
 
 ## Theming System
 
+### Error Boundary Pattern
+
+**Date:** 2026-02-01
+**Context:** Implemented global error handling
+
+**Implementation:**
+- Use Class Component for `componentDidCatch`
+- Use inner Functional Component for UI to support hooks (`useTheme`)
+- Place inside `ThemeProvider` but outside `Router` or deeply nested providers
+- Use `import.meta.env.DEV` to show stack traces in development
+- Ensure fallback UI supports both `NEOBRUTALISM` and `GLASSMORPHISM`
+
+**Files:** `web/components/ErrorBoundary.tsx`
+
 ### Web Dual-Theme Pattern
 **Date:** 2026-01-01
 **Context:** Understanding theme-switching mechanism

.Jules/todo.md

@@ -34,12 +34,10 @@
   - Impact: Guides new users, makes app feel polished
   - Size: ~70 lines
 
-- [ ] **[ux]** Error boundary with retry for API failures
-  - Files: Create `web/components/ErrorBoundary.tsx`, wrap app
-  - Context: Catch errors gracefully with retry button
-  - Impact: App doesn't crash, users can recover
-  - Size: ~60 lines
-  - Added: 2026-01-01
+- [x] **[ux]** Error boundary with retry for API failures
+  - Completed: 2026-02-01
+  - Files modified: `web/components/ErrorBoundary.tsx`, `web/App.tsx`
+  - Impact: App doesn't crash, users can recover gracefully
 
 ### Mobile
 

web/App.tsx

@@ -5,6 +5,7 @@ import { ThemeWrapper } from './components/layout/ThemeWrapper';
 import { AuthProvider, useAuth } from './contexts/AuthContext';
 import { ThemeProvider } from './contexts/ThemeContext';
 import { ToastProvider } from './contexts/ToastContext';
+import { ErrorBoundary } from './components/ErrorBoundary';
 import { ToastContainer } from './components/ui/Toast';
 import { Auth } from './pages/Auth';
 import { Dashboard } from './pages/Dashboard';
@@ -48,14 +49,16 @@ const AppRoutes = () => {
 const App = () => {
   return (
     <ThemeProvider>
-      <ToastProvider>
-        <AuthProvider>
-          <HashRouter>
-              <AppRoutes />
-              <ToastContainer />
-          </HashRouter>
-        </AuthProvider>
-      </ToastProvider>
+      <ErrorBoundary>
+        <ToastProvider>
+          <AuthProvider>
+            <HashRouter>
+                <AppRoutes />
+                <ToastContainer />
+            </HashRouter>
+          </AuthProvider>
+        </ToastProvider>
+      </ErrorBoundary>
     </ThemeProvider>
   );
 };

web/components/ErrorBoundary.tsx

@@ -0,0 +1,100 @@
+import React, { Component, ReactNode } from 'react';
+import { AlertTriangle, RefreshCw } from 'lucide-react';
+import { useTheme } from '../contexts/ThemeContext';
+import { THEMES } from '../constants';
+import { Button } from './ui/Button';
+
+interface Props {
+  children: ReactNode;
+}
+
+interface State {
+  hasError: boolean;
+  error?: Error;
+}
+
+const ErrorFallback = ({ error, resetErrorBoundary }: { error?: Error, resetErrorBoundary: () => void }) => {
+  const { style, mode } = useTheme();
+  const isNeo = style === THEMES.NEOBRUTALISM;
+  const isDark = mode === 'dark';
+
+  return (
+    <div className={`min-h-[500px] w-full flex flex-col items-center justify-center p-6 text-center
+      ${isNeo ? 'bg-neo-bg text-black' : isDark ? 'text-white' : 'text-gray-900'}
+    `}>
+      <div className={`
+        max-w-md w-full p-8 flex flex-col items-center gap-6
+        ${isNeo
+          ? 'bg-white border-2 border-black shadow-[8px_8px_0px_0px_rgba(0,0,0,1)]'
+          : `backdrop-blur-xl border ${isDark ? 'bg-white/10 border-white/20' : 'bg-white/70 border-white/40'} rounded-2xl shadow-xl`
+        }
+      `}>
+        <div className={`
+          p-4 rounded-full flex items-center justify-center
+          ${isNeo
+            ? 'bg-red-400 border-2 border-black'
+            : 'bg-red-500/20 text-red-500'
+          }
+        `}>
+          <AlertTriangle size={48} className={isNeo ? 'text-black' : 'currentColor'} aria-hidden="true" />
+        </div>
+
+        <div className="space-y-3">
+          <h2 className="text-2xl font-bold" role="alert">Something went wrong</h2>
+          <p className={`${isNeo ? 'text-gray-700' : isDark ? 'text-gray-300' : 'text-gray-600'}`}>
+            We encountered an unexpected error. Please try reloading the page.
+          </p>
+
+          {import.meta.env.DEV && error && (
+            <div className="mt-4 w-full">
+              <p className="text-xs font-mono text-left mb-1 opacity-70">Error details:</p>
+              <pre className={`
+                p-3 text-xs text-left overflow-auto max-h-40 w-full rounded
+                ${isNeo ? 'bg-gray-100 border border-black text-black' : 'bg-black/30 text-white/90'}
+              `}>
+                {error.message}
+              </pre>
+            </div>
+          )}
+        </div>
+
+        <Button
+          onClick={resetErrorBoundary}
+          variant="primary"
+          className="w-full flex items-center justify-center gap-2 mt-2"
+        >
+          <RefreshCw size={18} aria-hidden="true" />
+          Reload Page
+        </Button>
+      </div>
+    </div>
+  );
+};
+
+export class ErrorBoundary extends Component<Props, State> {
+  constructor(props: Props) {
+    super(props);
+    this.state = { hasError: false };
+  }
+
+  static getDerivedStateFromError(error: Error) {
+    return { hasError: true, error };
+  }
+
+  componentDidCatch(error: Error, errorInfo: React.ErrorInfo) {
+    console.error('ErrorBoundary caught an error:', error, errorInfo);
+  }
+
+  resetErrorBoundary = () => {
+    this.setState({ hasError: false, error: undefined });
+    window.location.reload();
+  };
+
+  render() {
+    if (this.state.hasError) {
+      return <ErrorFallback error={this.state.error} resetErrorBoundary={this.resetErrorBoundary} />;
+    }
+
+    return this.props.children;
+  }
+}