List<T> findAll<T>({
  bool includeSubtypes = true,  // NEW!
  bool inAllScopes = false,
  String? onlyInScope,
});

getIt.registerSingleton<FileOutput>(FileOutput());
getIt.registerSingleton<EnhancedFileOutput>(EnhancedFileOutput()); // extends FileOutput

// Include subtypes (default)
findAll<FileOutput>()  // Returns: [FileOutput, EnhancedFileOutput]

// Exact type only
findAll<FileOutput>(includeSubtypes: false)  // Returns: [FileOutput] only

// Check if T is a subtype of S
bool canBeRetrievedAs<S>() => <T>[] is List<S>;

// Check if T is exactly S (bidirectional)
bool isExactType<S>() => <T>[] is List<S> && <S>[] is List<T>;

// Current scope only (default)
findAll<Disposable>()

// All scopes
findAll<Disposable>(inAllScopes: true)

// Specific named scope
findAll<Disposable>(onlyInScope: 'userSession')

// Clean up only user session resources
for (final cache in findAll<CacheService>(onlyInScope: 'userSession')) {
  await cache.clear();
}

// Dispose all across all scopes on app shutdown
for (final disposable in findAll<Disposable>(inAllScopes: true)) {
  disposable.dispose();
}

Iterable<T> getAll<T>({
  dynamic param1,
  dynamic param2,
  bool fromAllScopes = false,  // Existing
  String? onlyInScope,         // NEW
});

// Setup
getIt.registerSingleton<FileOutput>(FileOutput());
getIt.registerSingleton<ConsoleOutput>(ConsoleOutput());

// getAll<IOutput>() - ❌ Throws: Nothing registered AS IOutput
// findAll<IOutput>() - ✅ Returns: [FileOutput, ConsoleOutput]