# Error Boundary Usage Audit

**Date**: 2026-01-11  
**Action**: 3.3.1.1 - Audit existing ErrorBoundary usage  
**Status**: ✅ Complete

## Summary

This document audits the current usage of ErrorBoundary components across the application to identify coverage gaps and areas for improvement.

## ErrorBoundary Components Found

### 1. Main ErrorBoundary Component
**File**: `apps/web/src/components/ErrorBoundary.tsx`
- **Type**: Class component extending React.Component
- **Features**:
  - Logs errors to structured logger
  - Sends errors to Sentry
  - Custom fallback UI support
  - Reset functionality
  - Dev mode error details display
- **Current Usage**: Wraps entire app in `App.tsx` (line 122)

### 2. PlaylistErrorBoundary Component
**File**: `apps/web/src/features/playlists/components/PlaylistErrorBoundary.tsx`
- **Type**: Class component extending React.Component
- **Features**:
  - Specialized for playlist components
  - Uses ErrorDisplay component for fallback UI (already updated per Action 3.1.1.10)
  - Reset functionality
  - Custom fallback support
- **Current Usage**: Wraps playlist-specific components

### 3. LazyErrorBoundary Component
**File**: `apps/web/src/components/ui/LazyComponent.tsx`
- **Type**: Class component extending React.Component
- **Features**:
  - Specialized for lazy-loaded components
  - Custom fallback UI (LazyErrorFallback)
  - Retry functionality
- **Current Usage**: Wraps lazy-loaded page components

## Current Coverage

### ✅ Covered Areas

1. **App-Level Coverage**
   - `App.tsx` wraps entire application with `ErrorBoundary`
   - Catches all unhandled React errors at the top level

2. **Playlist Components**
   - `PlaylistErrorBoundary` wraps playlist-specific components
   - Provides specialized error handling for playlist operations

3. **Lazy-Loaded Components**
   - `LazyErrorBoundary` wraps lazy-loaded page components
   - Handles code-splitting errors

### ❌ Gaps Identified

1. **Route-Level Coverage**
   - **Issue**: No ErrorBoundary wrapping individual routes
   - **Impact**: If one route crashes, entire app may become unusable
   - **Recommendation**: Wrap each route with ErrorBoundary (Action 3.3.1.2)

2. **Feature-Level Coverage**
   - **Issue**: Only playlists have feature-specific error boundary
   - **Impact**: Other features (tracks, library, marketplace, chat) lack isolated error handling
   - **Recommendation**: Consider feature-specific boundaries for critical features

3. **Component-Level Coverage**
   - **Issue**: No boundaries around individual components that might fail
   - **Impact**: Component failures can propagate up to route/app level
   - **Recommendation**: Add boundaries for complex components (modals, forms, data-heavy components)

## Router Structure

**File**: `apps/web/src/router/index.tsx`
- Uses React Router for routing
- Routes are defined but not individually wrapped with ErrorBoundary
- All routes are currently protected by app-level ErrorBoundary only

## Recommendations

### High Priority

1. **Wrap Individual Routes** (Action 3.3.1.2)
   - Add ErrorBoundary to each route definition
   - Prevents one route crash from affecting entire app
   - Allows route-specific error recovery

2. **Update ErrorBoundary UI** (Action 3.3.1.3)
   - Replace custom fallback UI with ErrorDisplay component
   - Provides consistent error presentation
   - Already done for PlaylistErrorBoundary

### Medium Priority

3. **Add Feature-Level Boundaries**
   - Consider boundaries for:
     - Track upload/management features
     - Marketplace features
     - Chat features
     - Library features

4. **Component-Level Boundaries**
   - Add boundaries for:
     - Complex modals (UploadModal, ShareDialog)
     - Data-heavy components (LibraryPage, MarketplaceHome)
     - Forms with complex validation

### Low Priority

5. **Error Boundary Logging** (Action 3.3.1.4)
   - Enhance logging with more context
   - Add user action tracking
   - Improve error correlation

## Files Requiring Updates

1. `apps/web/src/router/index.tsx` - Add ErrorBoundary to routes
2. `apps/web/src/components/ErrorBoundary.tsx` - Update to use ErrorDisplay (Action 3.3.1.3)
3. Feature components - Consider adding feature-specific boundaries

## Next Steps

1. ✅ Complete: Audit existing ErrorBoundary usage
2. ⏭️ Next: Wrap all routes in ErrorBoundary (Action 3.3.1.2)
3. ⏭️ Next: Update ErrorBoundary to use ErrorDisplay (Action 3.3.1.3)
4. ⏭️ Next: Add error boundary logging (Action 3.3.1.4)