diff --git a/finlog_app/app/lib/core/ui/controller/locale_controller.dart b/finlog_app/app/lib/core/ui/controller/locale_controller.dart
new file mode 100644
index 0000000..127b163
--- /dev/null
+++ b/finlog_app/app/lib/core/ui/controller/locale_controller.dart
@@ -0,0 +1,42 @@
+import 'package:flutter/material.dart';
+import 'package:fluttery/fluttery.dart';
+import 'package:fluttery/preferences.dart';
+
+/// Controls the current app language (system, de, en, ...).
+/// Loads the locale from Preferences or falls back to system default.
+class LocaleController extends ChangeNotifier {
+  final Preferences _prefs;
+
+  LocaleController() : _prefs = App.service<Preferences>();
+
+  static const _key = 'language';
+
+  String _current = 'system';
+
+  Future<void> init() async {
+    final saved = await _prefs.getString(_key);
+    _current = saved ?? 'system';
+    notifyListeners();
+  }
+
+  void setLanguage(String lang) {
+    _current = lang;
+    notifyListeners();
+    _prefs.setString(_key, lang);
+  }
+
+  /// Returns the actual Locale or null = system.
+  Locale? get locale {
+    switch (_current) {
+      case 'de':
+        return const Locale('de');
+      case 'en':
+        return const Locale('en');
+      case 'system':
+      default:
+        return null;
+    }
+  }
+
+  String get language => _current;
+}
diff --git a/finlog_app/app/lib/core/ui/controller/scale_controller.dart b/finlog_app/app/lib/core/ui/controller/scale_controller.dart
new file mode 100644
index 0000000..241bb36
--- /dev/null
+++ b/finlog_app/app/lib/core/ui/controller/scale_controller.dart
@@ -0,0 +1,47 @@
+import 'package:flutter/material.dart';
+import 'package:fluttery/fluttery.dart';
+import 'package:fluttery/preferences.dart';
+
+/// Controls the current text scale (system, small, medium, large).
+/// Loads the value from Preferences or falls back to system default.
+class ScaleController extends ChangeNotifier {
+  final Preferences _prefs;
+
+  ScaleController() : _prefs = App.service<Preferences>();
+
+  static const _key = 'textScale';
+
+  /// supported sizes
+  static const Map<String, double> _factors = {
+    'system': 1.0,
+    'small': 0.9,
+    'medium': 1.1,
+    'large': 1.25,
+  };
+
+  String _current = 'system';
+
+  /// Loads text scale from Preferences.
+  Future<void> init() async {
+    final saved = await _prefs.getString(_key);
+    _current = saved ?? 'system';
+    if (!_factors.containsKey(_current)) {
+      _current = 'system';
+    }
+    notifyListeners();
+  }
+
+  /// Set text scale and persist.
+  void setScale(String scale) {
+    if (!_factors.containsKey(scale)) return;
+    _current = scale;
+    notifyListeners();
+    _prefs.setString(_key, scale);
+  }
+
+  /// get current factor (e.g. for MediaQuery.textScaler)
+  double get factor => _factors[_current]!;
+
+  /// get current string (system/small/medium/large)
+  String get scale => _current;
+}
diff --git a/finlog_app/app/lib/core/app/theme.dart b/finlog_app/app/lib/core/ui/controller/theme.dart
similarity index 94%
rename from finlog_app/app/lib/core/app/theme.dart
rename to finlog_app/app/lib/core/ui/controller/theme.dart
index b57954c..f061e0f 100644
--- a/finlog_app/app/lib/core/app/theme.dart
+++ b/finlog_app/app/lib/core/ui/controller/theme.dart
@@ -7,7 +7,7 @@ import 'package:fluttery/preferences.dart';
 class ThemeController extends ChangeNotifier {
   final Preferences _prefs;
 
-  // vars
+  /// themeMode (system, dark or white)
   ThemeMode _themeMode = ThemeMode.system;
 
   /// Constructor
@@ -43,5 +43,6 @@ class ThemeController extends ChangeNotifier {
     }
   }
 
+  /// get current ThemeMode
   ThemeMode get themeMode => _themeMode;
 }
diff --git a/finlog_app/app/lib/main.dart b/finlog_app/app/lib/main.dart
index b6402cb..3ea7a71 100644
--- a/finlog_app/app/lib/main.dart
+++ b/finlog_app/app/lib/main.dart
@@ -1,6 +1,6 @@
 import 'package:app/core/app/router.dart';
 import 'package:app/core/app/startup/domain/initialize_app.dart';
-import 'package:app/core/app/theme.dart';
+import 'package:app/core/ui/controller/theme.dart';
 import 'package:flutter/material.dart';
 import 'package:fluttery/fluttery.dart';
 import 'package:fluttery/logger.dart';
diff --git a/finlog_app/app/lib/modules/settings/modules/app/app_settings_view.dart b/finlog_app/app/lib/modules/settings/modules/app/app_settings_view.dart
index 4c0bd9b..e251f20 100644
--- a/finlog_app/app/lib/modules/settings/modules/app/app_settings_view.dart
+++ b/finlog_app/app/lib/modules/settings/modules/app/app_settings_view.dart
@@ -1,4 +1,4 @@
-import 'package:app/core/app/theme.dart';
+import 'package:app/core/ui/controller/theme.dart';
 import 'package:app/modules/settings/modules/app/model/app_settings_view_model.dart';
 import 'package:flutter/material.dart';
 import 'package:provider/provider.dart';
diff --git a/finlog_app/app/lib/modules/settings/modules/app/model/app_settings_view_model.dart b/finlog_app/app/lib/modules/settings/modules/app/model/app_settings_view_model.dart
index f9ac6ae..842e5c2 100644
--- a/finlog_app/app/lib/modules/settings/modules/app/model/app_settings_view_model.dart
+++ b/finlog_app/app/lib/modules/settings/modules/app/model/app_settings_view_model.dart
@@ -1,4 +1,4 @@
-import 'package:app/core/app/theme.dart';
+import 'package:app/core/ui/controller/theme.dart';
 import 'package:flutter/material.dart';
 
 /// Domain-ish enums for clarity and easy (de)serialization.