שני מסכים, מודל אחד

import 'package:flutter/material.dart';
import 'package:provider/provider.dart';

class Profile extends ChangeNotifier {
  String _name = 'Guest';

  String get name => _name;

  void rename(String newName) {
    _name = newName;
    notifyListeners();
  }
}

void main() {
  runApp(const MyApp());
}

class MyApp extends StatelessWidget {
  const MyApp({super.key});

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      debugShowCheckedModeBanner: false,
      home: ChangeNotifierProvider(
        create: (context) => Profile(),
        child: const HomePage(),
      ),
    );
  }
}

class HomePage extends StatelessWidget {
  const HomePage({super.key});

  @override
  Widget build(BuildContext context) {
    final profile = context.watch<Profile>();
    return Scaffold(
      appBar: AppBar(
        title: const Text('Home'),
        actions: [
          IconButton(
            icon: const Icon(Icons.settings),
            onPressed: () {
              Navigator.push(
                context,
                MaterialPageRoute(builder: (context) => const SettingsScreen()),
              );
            },
          ),
        ],
      ),
      body: Center(
        child: Text('Hello, ${profile.name}!', style: const TextStyle(fontSize: 32)),
      ),
    );
  }
}

class SettingsScreen extends StatefulWidget {
  const SettingsScreen({super.key});

  @override
  State<SettingsScreen> createState() => _SettingsScreenState();
}

class _SettingsScreenState extends State<SettingsScreen> {
  final controller = TextEditingController();

  @override
  Widget build(BuildContext context) {
    final profile = context.watch<Profile>();
    return Scaffold(
      appBar: AppBar(title: const Text('Settings')),
      body: Padding(
        padding: const EdgeInsets.all(16),
        child: Column(
          children: [
            Text('Signed in as ${profile.name}'),
            const SizedBox(height: 16),
            TextField(
              controller: controller,
              decoration: const InputDecoration(labelText: 'Your name'),
            ),
            const SizedBox(height: 16),
            ElevatedButton(
              onPressed: () {
                context.read<Profile>().rename(controller.text);
                Navigator.pop(context);
              },
              child: const Text('Save'),
            ),
          ],
        ),
      ),
    );
  }
}