evanca/flutter-ai-rules/firebase-remote-config

Firebase Remote Config Skill

This skill defines how to correctly use Firebase Remote Config in Flutter applications.

When to Use

Use this skill when:

• Implementing feature flags or remote configuration without deploying app updates.
• Managing parameter defaults and fetching remote values.
• Implementing real-time config updates for instant changes.
• Setting up A/B testing or conditional targeting for user segments.

1. Setup and Configuration

flutter pub add firebase_remote_config
flutter pub add firebase_analytics  # required for conditional targeting of app instances

import 'package:firebase_remote_config/firebase_remote_config.dart';
 
final remoteConfig = FirebaseRemoteConfig.instance;

• Enable Google Analytics in the Firebase project for user property and audience targeting.
• Ensure the Remote Config REST API is not disabled — the SDK depends on it.
• For macOS, enable Keychain Sharing in Xcode.

Configure settings:

await remoteConfig.setConfigSettings(RemoteConfigSettings(
  fetchTimeout: const Duration(minutes: 1),
  minimumFetchInterval: const Duration(hours: 1),
));

2. Parameter Management

Set in-app defaults (ensures the app behaves as intended before connecting to the backend):

await remoteConfig.setDefaults(const {
  "feature_new_onboarding": false,
  "max_retry_attempts": 3,
  "welcome_message": "Hello, world!",
  "promo_discount_pct": 0.0,
});

Read values with type-specific getters:

final showNewOnboarding = remoteConfig.getBool("feature_new_onboarding");
final maxRetries = remoteConfig.getInt("max_retry_attempts");
final welcomeMsg = remoteConfig.getString("welcome_message");
final discount = remoteConfig.getDouble("promo_discount_pct");

• Never store confidential data in Remote Config keys or values — they can be accessed by end users.
• Define parameters with the same names in the Firebase console as those in the app.
• Group related parameters with common prefixes (e.g., login_timeout, login_attempts_max).

3. Fetching and Activating

await remoteConfig.fetchAndActivate();

• Use fetchAndActivate() to fetch and apply values in a single call.
• Alternatively, call fetch() then activate() separately to control when values take effect.
• Activate fetched values at appropriate times (e.g., app start) for a smooth user experience.
• Check remoteConfig.lastFetchStatus to determine if the fetch was successful, failed, or throttled.
• Handle fetch failures gracefully — default values are used automatically when fetch fails.

4. Real-time Updates

remoteConfig.onConfigUpdated.listen((event) async {
  await remoteConfig.activate();
  // event.updatedKeys contains the changed parameter names
  if (event.updatedKeys.contains("feature_new_onboarding")) {
    // Refresh UI based on the new value
  }
});

• Real-time Remote Config is not available for Web.
• Update UI state when new configuration values are activated.
• Ensure real-time updates do not disrupt the user experience mid-flow.

5. Throttling and Performance

• Fetch calls are throttled if an app fetches too frequently.
• Default minimum fetch interval in production: 12 hours.
• For development, use a shorter interval — but only in debug builds:

await remoteConfig.setConfigSettings(RemoteConfigSettings(
  fetchTimeout: const Duration(minutes: 1),
  minimumFetchInterval: const Duration(minutes: 5),
));

• Be mindful of service-side quota limits with a large user base.

6. Testing and Debugging

• Use conditional values in the Firebase console to test configurations without new app deployments.
• Implement A/B testing with different parameter values for different user segments.
• Test the app with both default and remote values.
• Verify graceful handling of configuration changes at runtime.
• Test offline behavior to ensure proper fallback to defaults.

References

• Firebase Remote Config Flutter documentation