import 'package:flutter/material.dart'; import 'package:shared_preferences/shared_preferences.dart'; Future saveDarkMode(bool isDark) async { final prefs = await SharedPreferences.getInstance(); await prefs.setBool('darkMode', isDark); } Future loadDarkMode() async { final prefs = await SharedPreferences.getInstance(); return prefs.getBool('darkMode') ?? false; // default light } class ThemeProvider extends ChangeNotifier { bool _isDark = false; bool get isDark => _isDark; ThemeProvider() { _load(); // load saved value on startup } void _load() async { _isDark = await loadDarkMode(); notifyListeners(); } void setDarkMode(bool value) async { _isDark = value; notifyListeners(); await saveDarkMode(value); } }