enhance: Add error boundary with retry mechanism

.Jules/changelog.md

@@ -7,6 +7,7 @@
 ## [Unreleased]
 
 ### Added
+- Error Boundary system (`ErrorBoundary`, `ErrorFallback`) to catch and handle runtime errors gracefully with dual-theme support and retry mechanism.
 - 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

@@ -338,6 +338,28 @@ Use `AnimatePresence` for exit animations.
 
 ---
 
+## Verification Patterns
+
+### Error Boundary Verification
+
+**Date:** 2026-01-14
+**Context:** Verifying `ErrorBoundary` works as expected
+
+Since Error Boundaries only catch errors during rendering, lifecycle methods, or constructors (and not in event handlers or async code by default, though React handles some), verifying them requires triggering a render error.
+
+**How to verify:**
+1. Temporarily modify a component (e.g., `Auth.tsx`) to throw an error inside the render body:
+   ```tsx
+   if (typeof window !== 'undefined') {
+     throw new Error('Test Error');
+   }
+   ```
+2. Navigate to that page.
+3. Verify the fallback UI appears.
+4. **Revert the change** immediately after verification.
+
+---
+
 ## Best Practices Learned
 
 ### 1. Accessibility First

.Jules/todo.md

@@ -34,12 +34,12 @@
   - Impact: Guides new users, makes app feel polished
   - Size: ~70 lines
 
-- [ ] **[ux]** Error boundary with retry for API failures
+- [x] **[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
+  - Completed: 2026-01-14
 
 ### Mobile
 

web/App.tsx

@@ -6,6 +6,7 @@ import { AuthProvider, useAuth } from './contexts/AuthContext';
 import { ThemeProvider } from './contexts/ThemeContext';
 import { ToastProvider } from './contexts/ToastContext';
 import { ToastContainer } from './components/ui/Toast';
+import { ErrorBoundary } from './components/ErrorBoundary';
 import { Auth } from './pages/Auth';
 import { Dashboard } from './pages/Dashboard';
 import { Friends } from './pages/Friends';
@@ -51,8 +52,10 @@ const App = () => {
       <ToastProvider>
         <AuthProvider>
           <HashRouter>
+            <ErrorBoundary>
               <AppRoutes />
               <ToastContainer />
+            </ErrorBoundary>
           </HashRouter>
         </AuthProvider>
       </ToastProvider>

web/components/ErrorBoundary.tsx

@@ -0,0 +1,95 @@
+import React, { Component, ErrorInfo, 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 | null;
+}
+
+const ErrorFallback: React.FC<{ error: Error | null; resetErrorBoundary: () => void }> = ({
+  error,
+  resetErrorBoundary
+}) => {
+  const { style } = useTheme();
+  const isNeo = style === THEMES.NEOBRUTALISM;
+
+  return (
+    <div className="min-h-[50vh] w-full flex items-center justify-center p-4">
+      <div
+        className={`
+          max-w-md w-full p-8 text-center flex flex-col items-center gap-6
+          ${isNeo
+            ? 'bg-white border-4 border-black shadow-[8px_8px_0px_0px_rgba(0,0,0,1)]'
+            : 'bg-white/10 backdrop-blur-md border border-white/20 rounded-2xl shadow-xl'
+          }
+        `}
+      >
+        <div className={`
+          p-4 rounded-full
+          ${isNeo ? 'bg-neo-second border-2 border-black' : 'bg-red-500/20 text-red-200'}
+        `}>
+          <AlertTriangle size={48} className={isNeo ? 'text-black' : 'text-red-400'} />
+        </div>
+
+        <div className="space-y-2">
+          <h2 className={`text-2xl font-bold ${isNeo ? 'font-black uppercase' : 'text-white'}`}>
+            Something went wrong
+          </h2>
+          <p className={isNeo ? 'text-black font-medium' : 'text-gray-300'}>
+            We encountered an unexpected error. Try reloading the page to get back on track.
+          </p>
+        </div>
+
+        {error && process.env.NODE_ENV === 'development' && (
+          <div className="w-full text-left p-4 bg-black/5 rounded text-xs font-mono overflow-auto max-h-32">
+            {error.toString()}
+          </div>
+        )}
+
+        <Button
+          onClick={resetErrorBoundary}
+          variant="primary"
+          className="w-full"
+        >
+          <RefreshCw size={18} />
+          Reload Application
+        </Button>
+      </div>
+    </div>
+  );
+};
+
+export class ErrorBoundary extends Component<Props, State> {
+  public state: State = {
+    hasError: false,
+    error: null
+  };
+
+  public static getDerivedStateFromError(error: Error): State {
+    return { hasError: true, error };
+  }
+
+  public componentDidCatch(error: Error, errorInfo: ErrorInfo) {
+    console.error('Uncaught error:', error, errorInfo);
+  }
+
+  public render() {
+    if (this.state.hasError) {
+      return (
+        <ErrorFallback
+          error={this.state.error}
+          resetErrorBoundary={() => window.location.reload()}
+        />
+      );
+    }
+
+    return this.props.children;
+  }
+}