CARP Debug

An in-app debug toolkit. Adds a button with a debug menu which is independent of the host app's widget tree. This toolkit was designed to be used in CARP Flutter apps (Android + iOS) but can be used in any Flutter app. See the CARP Debug Flutter example and CARP Debug Docs

Features

Tool	What it does
Environment & Servers	Switch the deployment server and override any launch argument (--dart-define) at runtime, then Apply (live reconfigure) or Restart.
Shared Preferences	Inspect, search, edit, add and delete any key in a SharedPreferences store (the CARP user/session data).
Database	Browse the local sembast database: stores, records (pretty-printed JSON), delete records / clear stores.
Device & App	Device + app metadata (model, OS, version, build) plus screen metrics.
Logs & Errors	Captured debugPrint output, framework errors and uncaught async errors.

Everything is extensible: register your own screens via DebugTool and add extra KeyValueStore / DebugDatabase data sources.

---

CarpDebugToolkit wraps the whole app in a root Stack and renders its UI in its own scope (MediaQuery, Theme, Localizations, ScaffoldMessenger and a dedicated Navigator). Because the overlay sits above the host MaterialApp and never uses the host's router, a crashing screen or broken navigation does not remove the button or the menu.

Note that however, a synchronous infinite loop on the UI isolate blocks all Dart rendering (the toolkit included). The toolkit can handle crashes, exceptions and broken navigation.

Runtime launch-argument overrides (DebugEnv)

CARP apps read config such as the deployment mode with String.fromEnvironment, which is fixed at build time. DebugEnv adds a runtime override layer that is persisted across restarts.

// 1. Load persisted overrides before anything reads configuration.
await DebugEnv().initialize();
DebugEnv().registerAll(const [
  EnvEntry(
    key: 'deployment-mode',
    label: 'Deployment mode',
    type: EnvValueType.enumeration,
    options: ['production', 'test', 'dev'],
    fallback: String.fromEnvironment('deployment-mode', defaultValue: 'production'),
  ),
]);

// 2. Read config through DebugEnv instead of String.fromEnvironment.
final mode = DebugEnv().string('deployment-mode',
    fallback: const String.fromEnvironment('deployment-mode', defaultValue: 'production'));

Usage

import 'package:carp_debug_flutter/carp_debug_flutter.dart';
import 'package:flutter/foundation.dart';
import 'package:shared_preferences/shared_preferences.dart';

Future<void> main() async {
  WidgetsFlutterBinding.ensureInitialized();
  final prefs = await SharedPreferences.getInstance();
  await DebugEnv().initialize(preferences: prefs);

  final db = await openMySembastDatabase();

  runApp(CarpDebugToolkit(
    enabled: kDebugMode, // or bool.fromEnvironment('debug-toolkit', defaultValue: kDebugMode)
    config: DebugToolkitConfig(
      title: 'My App Debug',
      envEntries: myEnvEntries,
      keyValueStores: [SharedPreferencesKeyValueStore(prefs)],
      databases: [SembastDebugDatabase(db, [
        SembastStoreDescriptor('settings', StoreRef<String, Object?>.main()),
        SembastStoreDescriptor('results', intMapStoreFactory.store('results')),
      ])],
      onApply: () => myBackend.reconfigure(),        // live reconfigure
      onReinitialize: () => myBackend.reconfigure(), // before in-process restart
    ),
    child: const MyApp(),
  ));
}

See example/ for a complete, runnable demo with SharedPreferences + sembast data and a custom server field.

Production builds

It is good practice to not ship the toolkit to end users. To keep it out of production archives:

1. Install as dev_dependencies
2. Reference it only from kDebugMode-gated code so Dart tree-shaking removes it; production code reads launch arguments through an app-local hook (String? Function(String)? debugLaunchOverride) rather than importing the package.

// main.dart — folds to `runApp(app)` in release; the wrapper (and the whole
// package) is tree-shaken away, and the dev-dependency native is excluded.
if (kDebugMode) await debug.initializeDebugTools();
runApp(kDebugMode ? debug.wrapWithDebugToolkit(app, db) : app);

On Android the plugin is fully excluded from the release archive (absent from the release GeneratedPluginRegistrant). On iOS the Dart is excluded; the small native stub is still linked but inert (Dart never calls it) due to flutter#163874.

Custom tools

You can add your own custom tools by implementing the DebugTool interface.

class MyTool implements DebugTool {
  @override String get id => 'my-tool';
  @override String get title => 'My Tool';
  @override String? get subtitle => 'Does something useful';
  @override IconData get icon => Icons.science;
  @override Widget buildPage(BuildContext context) =>
      const DebugScaffold(title: 'My Tool', body: Center(child: Text('Hi')));
}
// DebugToolkitConfig(extraTools: [MyTool()])

License

See LICENSE.