setup-observer

name: setup-observer description: Configure Superpowers.observer for performance tracking, analytics, and debugging of all mix() calls

Setup Global Observer

This skill configures Superpowers.observer for performance tracking, analytics, and debugging of all mix() calls.

What This Skill Does

Sets up a global observer that:

• Tracks when operations start and complete
• Measures operation duration
• Captures errors and success states
• Sends data to analytics/monitoring services

Instructions

Step 1: Configure in main()

Set Superpowers.observer before runApp():

import 'package:bloc_superpowers/bloc_superpowers.dart';
import 'package:flutter/material.dart';

void main() {
  Superpowers.observer = (
    bool isStart,
    Object key,
    Object? metrics,
    Object? error,
    StackTrace? stackTrace,
    Duration? duration,
  ) {
    // Handle observation
  };

  runApp(
    Superpowers(
      child: MaterialApp(...),
    ),
  );
}

Step 2: Understand Parameters

Common Patterns

Basic Logging

Superpowers.observer = (isStart, key, metrics, error, stackTrace, duration) {
  if (isStart) {
    print('▶ Starting: $key');
  } else {
    if (error != null) {
      print('✗ Failed: $key after ${duration?.inMilliseconds}ms - $error');
    } else {
      print('✓ Completed: $key in ${duration?.inMilliseconds}ms');
    }
  }
};

Performance Monitoring

Superpowers.observer = (isStart, key, metrics, error, stackTrace, duration) {
  if (!isStart && duration != null) {
    // Log slow operations
    if (duration.inMilliseconds > 1000) {
      print('⚠ Slow operation: $key took ${duration.inMilliseconds}ms');
    }

    // Send to analytics
    analytics.logTiming(
      category: 'cubit_operation',
      name: key.toString(),
      duration: duration,
      success: error == null,
    );
  }
};

Analytics Integration

Superpowers.observer = (isStart, key, metrics, error, stackTrace, duration) {
  if (!isStart) {
    // Firebase Analytics
    FirebaseAnalytics.instance.logEvent(
      name: 'cubit_operation',
      parameters: {
        'key': key.toString(),
        'duration_ms': duration?.inMilliseconds,
        'success': error == null,
        'error_type': error?.runtimeType.toString(),
      },
    );

    // Or Amplitude
    Amplitude.instance.logEvent(
      'cubit_operation_completed',
      eventProperties: {
        'key': key.toString(),
        'duration_ms': duration?.inMilliseconds,
        'success': error == null,
      },
    );
  }
};

Error Monitoring

Superpowers.observer = (isStart, key, metrics, error, stackTrace, duration) {
  if (!isStart && error != null) {
    // Send to Sentry
    Sentry.captureException(
      error,
      stackTrace: stackTrace,
      hint: Hint.withMap({
        'key': key.toString(),
        'duration_ms': duration?.inMilliseconds.toString(),
      }),
    );

    // Or Crashlytics
    FirebaseCrashlytics.instance.recordError(
      error,
      stackTrace,
      reason: 'mix operation failed: $key',
    );
  }
};

Using Metrics

Pass custom data to the observer with the metrics parameter:

Pass Current State

void loadUser() => mix(
  key: this,
  metrics: () => state,  // Pass current state
  () async {
    final user = await api.getUser();
    emit(user);
  },
);

// In observer
Superpowers.observer = (isStart, key, metrics, error, stackTrace, duration) {
  if (metrics != null) {
    print('State at ${isStart ? "start" : "end"}: $metrics');
  }
};

Pass Cubit Instance

void loadData() => mix(
  key: this,
  metrics: () => this,  // Pass entire Cubit
  () async {
    final data = await api.getData();
    emit(data);
  },
);

// In observer - access Cubit state
Superpowers.observer = (isStart, key, metrics, error, stackTrace, duration) {
  if (metrics is MyCubit) {
    print('Cubit state: ${metrics.state}');
  }
};

Pass Custom Metrics

void processOrder(Order order) => mix(
  key: this,
  metrics: () => {
    'orderId': order.id,
    'itemCount': order.items.length,
    'total': order.total,
  },
  () async {
    await api.processOrder(order);
  },
);

// In observer
Superpowers.observer = (isStart, key, metrics, error, stackTrace, duration) {
  if (metrics is Map) {
    analytics.logEvent('order_processing', parameters: metrics);
  }
};

Behavior Notes

• Called twice: Once at start (isStart: true), once at end (isStart: false)
• Retry transparency: With retry, observer only sees the overall start/end, not individual attempts
• Error safety: If the metrics callback or observer throws, the error is captured safely
• Metrics called twice: The metrics callback runs at both start and end, so you can see state changes

Complete Example

void main() {
  _setupObserver();

  runApp(
    Superpowers(
      child: MyApp(),
    ),
  );
}

void _setupObserver() {
  Superpowers.observer = (
    bool isStart,
    Object key,
    Object? metrics,
    Object? error,
    StackTrace? stackTrace,
    Duration? duration,
  ) {
    final keyStr = _formatKey(key);

    if (isStart) {
      // Log operation start
      debugPrint('▶ [$keyStr] Starting');
    } else {
      // Log operation completion
      final durationMs = duration?.inMilliseconds ?? 0;

      if (error != null) {
        debugPrint('✗ [$keyStr] Failed after ${durationMs}ms: $error');

        // Report to crash analytics
        _reportError(key, error, stackTrace, duration);
      } else {
        debugPrint('✓ [$keyStr] Completed in ${durationMs}ms');

        // Report slow operations
        if (durationMs > 2000) {
          _reportSlowOperation(key, duration!);
        }
      }

      // Send analytics
      _sendAnalytics(key, duration, error == null);
    }
  };
}

String _formatKey(Object key) {
  if (key is Type) return key.toString();
  if (key is Record) return key.toString();
  return key.runtimeType.toString();
}

void _reportError(Object key, Object error, StackTrace? stack, Duration? duration) {
  FirebaseCrashlytics.instance.recordError(
    error,
    stack,
    reason: 'Operation failed: $key',
    information: ['Duration: ${duration?.inMilliseconds}ms'],
  );
}

void _reportSlowOperation(Object key, Duration duration) {
  FirebaseAnalytics.instance.logEvent(
    name: 'slow_operation',
    parameters: {
      'key': key.toString(),
      'duration_ms': duration.inMilliseconds,
    },
  );
}

void _sendAnalytics(Object key, Duration? duration, bool success) {
  FirebaseAnalytics.instance.logEvent(
    name: 'cubit_operation',
    parameters: {
      'key': key.toString(),
      'duration_ms': duration?.inMilliseconds,
      'success': success,
    },
  );
}

Testing

Reset the observer between tests:

setUp(() {
  Superpowers.clear();  // Removes observer and resets state
});

User Preferences

Ask the user:

1. What should be logged? (start, completion, errors, slow operations)
2. Where to send analytics? (Firebase, Amplitude, custom backend)
3. Need custom metrics? (state, order details, etc.)