watch-finished-turbo/WATCHER_HEALTH_IMPLEMENTATION.md

Watcher Health Monitoring Implementation Summary

What Was Implemented

A comprehensive health monitoring and automatic recovery system for the file watcher service to ensure it continues running and automatically recovers if it crashes.

Files Created

1. Backend Service - /apps/service/src/watcher-health.service.ts

   • Monitors watcher health every 30 seconds
   • Detects unexpected watcher stops
   • Logs all errors to database
   • Implements automatic recovery with configurable limits
   • Provides health status and error log APIs

2. Frontend Component - /apps/web/src/app/components/WatcherHealthStatus.tsx

   • Displays real-time watcher health status (green/red indicator)
   • Shows recent error logs with timestamps
   • Allows viewing and clearing error history
   • Toggle button to enable/disable auto-recovery
   • WebSocket integration for real-time updates

3. Documentation - /docs/WATCHER_HEALTH_MONITORING.md

   • Complete feature documentation
   • Architecture overview
   • API endpoint reference
   • Configuration guide
   • Troubleshooting tips

Files Modified

1. App Module - /apps/service/src/app.module.ts

   • Added WatcherHealthService to providers

2. App Service - /apps/service/src/app.service.ts

   • Added health check method wrappers:
     • watcherHealthStatus()
     • watcherRecentErrors(limit?)
     • clearWatcherErrors()
     • setWatcherAutoRecovery(enabled)
     • isWatcherAutoRecoveryEnabled()

3. App Controller - /apps/service/src/app.controller.ts

   • Added 6 new HTTP endpoints:
     • GET /watcher/health - Get health status
     • GET /watcher/errors - List recent errors
     • DELETE /watcher/errors - Clear error logs
     • POST /watcher/auto-recovery - Set auto-recovery status
     • GET /watcher/auto-recovery - Get auto-recovery status

4. Watcher Service - /apps/service/src/watcher.service.ts

   • Added ready event listener to log when watcher is ready

5. Stats Section - /apps/web/src/app/components/StatsSection.tsx

   • Imported and integrated WatcherHealthStatus component
   • Added full-width health monitoring section to dashboard

Key Features

Health Monitoring

• ✅ Continuous monitoring every 30 seconds
• ✅ Detects when watcher unexpectedly stops
• ✅ Real-time status updates via WebSocket

Error Logging

• ✅ All errors logged to watcher_errors database table
• ✅ Automatic cleanup (keeps last 100 errors)
• ✅ Accessible via API and web UI

Automatic Recovery

• ✅ Configurable enable/disable
• ✅ Intelligent restart with last known configuration
• ✅ Recovery limiting (5 attempts per hour)
• ✅ Comprehensive logging of recovery attempts
• ✅ Automatic attempt counter reset after success

User Interface

• ✅ Health status dashboard with green/red indicator
• ✅ Error log viewer with timestamps
• ✅ Clear error logs button
• ✅ Auto-recovery toggle
• ✅ Real-time updates via WebSocket
• ✅ Toast notifications for user feedback

How It Works

User starts watcher
    ↓
WatcherHealthService begins monitoring
    ↓
Every 30 seconds: Health check runs
    ↓
Is watcher still running?
    ├─ YES: Continue monitoring (no action)
    └─ NO:
        ├─ Log error to database
        ├─ Emit WebSocket alert to UI
        └─ If auto-recovery enabled:
            ├─ Attempt restart with last config
            ├─ Log recovery attempt
            ├─ If successful: Reset attempt counter
            └─ If failed: Increment counter (max 5/hour)

Configuration

Auto-recovery is enabled by default. Users can:

1. Disable via UI - Click "Disable" in the Auto-Recovery section
2. Disable via API - POST /watcher/auto-recovery { "enabled": false }
3. Disable via database - Set watcher_auto_recovery setting to false

Testing the Feature

1. Start the watcher through the web UI
2. Kill the watcher process: pkill -f "watcher"
3. Observe automatic recovery (within 30 seconds):
   • Watcher should restart automatically
   • Dashboard should show recovery in progress
   • Error logs should record the failure
4. Check error logs: Click "View Errors" in the health panel
5. Clear logs: Click "Clear Log" button

API Usage Examples

# Get health status
curl http://localhost:3001/watcher/health

# Get recent errors
curl http://localhost:3001/watcher/errors?limit=20

# Clear error logs
curl -X DELETE http://localhost:3001/watcher/errors

# Enable auto-recovery
curl -X POST http://localhost:3001/watcher/auto-recovery \
  -H "Content-Type: application/json" \
  -d '{"enabled": true}'

# Check auto-recovery status
curl http://localhost:3001/watcher/auto-recovery

Build Status

✅ Build successful - All TypeScript compiles without errors ✅ Tests - Existing tests continue to pass ✅ No breaking changes - Fully backward compatible

Database Changes

New table created automatically on first run:

CREATE TABLE IF NOT EXISTS watcher_errors (
  id INTEGER PRIMARY KEY AUTOINCREMENT,
  timestamp TEXT NOT NULL,
  message TEXT NOT NULL,
  recovery_attempt INTEGER DEFAULT 0,
  created_at TEXT NOT NULL
);

No existing tables or data are affected.

Next Steps

Users can now:

1. Monitor watcher health in real-time
2. View detailed error logs with timestamps
3. Enable/disable automatic recovery as needed
4. Troubleshoot watcher issues more easily
5. Ensure watcher is always running when configured

Support

For detailed information, see /docs/WATCHER_HEALTH_MONITORING.md