Move my version to a different file and use the version from GitHub for further testing and analysis.

namer_app/lib/main.dart

@@ -1,3 +1,4 @@
+// https://github.com/flutter/codelabs/blob/main/namer/step_08/lib/main.dart
 import 'package:english_words/english_words.dart';
 import 'package:flutter/material.dart';
 import 'package:provider/provider.dart';
@@ -14,10 +15,10 @@ class MyApp extends StatelessWidget {
     return ChangeNotifierProvider(
       create: (context) => MyAppState(),
       child: MaterialApp(
-        title: 'Namer App (EXAMPLE PROJECT)',
+        title: 'Namer App',
         theme: ThemeData(
           useMaterial3: true,
-          colorScheme: ColorScheme.fromSeed(seedColor: Colors.purple),
+          colorScheme: ColorScheme.fromSeed(seedColor: Colors.deepOrange),
         ),
         home: MyHomePage(),
       ),
@@ -42,7 +43,6 @@ class MyAppState extends ChangeNotifier {
       favorites.add(current);
     }
     notifyListeners();
-    print("Favorites are: ${favorites.toString()}");
   }
 }
 
@@ -52,26 +52,21 @@ class MyHomePage extends StatefulWidget {
 }
 
 class _MyHomePageState extends State<MyHomePage> {
-
   var selectedIndex = 0;
 
   @override
   Widget build(BuildContext context) {
-
     Widget page;
     switch (selectedIndex) {
       case 0:
         page = GeneratorPage();
-        break;
       case 1:
         page = FavoritesPage();
-        break;
       default:
         throw UnimplementedError('no widget for $selectedIndex');
     }
 
-    return LayoutBuilder(
+    return LayoutBuilder(builder: (context, constraints) {
-      builder: (context, constraints) {
       return Scaffold(
         body: Row(
           children: [
@@ -93,7 +88,7 @@ class _MyHomePageState extends State<MyHomePage> {
                   setState(() {
                     selectedIndex = value;
                   });
-                  }
+                },
               ),
             ),
             Expanded(
@@ -105,40 +100,7 @@ class _MyHomePageState extends State<MyHomePage> {
           ],
         ),
       );
-      }
-    );
-  }
-}
-
-class FavoritesPage extends StatelessWidget {
-  const FavoritesPage({
-    super.key,
     });
-
-  @override
-  Widget build(BuildContext context) {
-    var appState = context.watch<MyAppState>();
-
-    if (appState.favorites.isEmpty) {
-      return Center(
-        child: Text('No favorites yet.'),
-      );
-    }
-
-    return ListView(
-      children: [
-        Padding(
-          padding: const EdgeInsets.all(20),
-          child: Text('You have '
-              '${appState.favorites.length} favorites:'),
-        ),
-        for (var pair in appState.favorites)
-          ListTile(
-            leading: Icon(Icons.favorite),
-            title: Text(pair.asLowerCase),
-          ),
-      ],
-    );
   }
 }
 
@@ -204,7 +166,7 @@ class BigCard extends StatelessWidget {
     return Card(
       color: theme.colorScheme.primary,
       child: Padding(
-        padding: const EdgeInsets.all(15.0),
+        padding: const EdgeInsets.all(20),
         child: Text(
           pair.asLowerCase,
           style: style,
@@ -214,3 +176,31 @@ class BigCard extends StatelessWidget {
     );
   }
 }
+
+class FavoritesPage extends StatelessWidget {
+  @override
+  Widget build(BuildContext context) {
+    var appState = context.watch<MyAppState>();
+
+    if (appState.favorites.isEmpty) {
+      return Center(
+        child: Text('No favorites yet.'),
+      );
+    }
+
+    return ListView(
+      children: [
+        Padding(
+          padding: const EdgeInsets.all(20),
+          child: Text('You have '
+              '${appState.favorites.length} favorites:'),
+        ),
+        for (var pair in appState.favorites)
+          ListTile(
+            leading: Icon(Icons.favorite),
+            title: Text(pair.asLowerCase),
+          ),
+      ],
+    );
+  }
+}

namer_app/lib/main_MyVersion20250130.dart

@@ -0,0 +1,216 @@
+import 'package:english_words/english_words.dart';
+import 'package:flutter/material.dart';
+import 'package:provider/provider.dart';
+
+void main() {
+  runApp(MyApp());
+}
+
+class MyApp extends StatelessWidget {
+  const MyApp({super.key});
+
+  @override
+  Widget build(BuildContext context) {
+    return ChangeNotifierProvider(
+      create: (context) => MyAppState(),
+      child: MaterialApp(
+        title: 'Namer App (EXAMPLE PROJECT)',
+        theme: ThemeData(
+          useMaterial3: true,
+          colorScheme: ColorScheme.fromSeed(seedColor: Colors.purple),
+        ),
+        home: MyHomePage(),
+      ),
+    );
+  }
+}
+
+class MyAppState extends ChangeNotifier {
+  var current = WordPair.random();
+
+  void getNext() {
+    current = WordPair.random();
+    notifyListeners();
+  }
+
+  var favorites = <WordPair>[];
+
+  void toggleFavorite() {
+    if (favorites.contains(current)) {
+      favorites.remove(current);
+    } else {
+      favorites.add(current);
+    }
+    notifyListeners();
+    print("Favorites are: ${favorites.toString()}");
+  }
+}
+
+class MyHomePage extends StatefulWidget {
+  @override
+  State<MyHomePage> createState() => _MyHomePageState();
+}
+
+class _MyHomePageState extends State<MyHomePage> {
+
+  var selectedIndex = 0;
+
+  @override
+  Widget build(BuildContext context) {
+
+    Widget page;
+    switch (selectedIndex) {
+      case 0:
+        page = GeneratorPage();
+        break;
+      case 1:
+        page = FavoritesPage();
+        break;
+      default:
+        throw UnimplementedError('no widget for $selectedIndex');
+    }
+
+    return LayoutBuilder(
+      builder: (context, constraints) {
+        return Scaffold(
+          body: Row(
+            children: [
+              SafeArea(
+                child: NavigationRail(
+                  extended: constraints.maxWidth >= 600,
+                  destinations: [
+                    NavigationRailDestination(
+                      icon: Icon(Icons.home),
+                      label: Text('Home'),
+                    ),
+                    NavigationRailDestination(
+                      icon: Icon(Icons.favorite),
+                      label: Text('Favorites'),
+                    ),
+                  ],
+                  selectedIndex: selectedIndex,
+                  onDestinationSelected: (value) {
+                    setState(() {
+                      selectedIndex = value;
+                    });
+                  }
+                ),
+              ),
+              Expanded(
+                child: Container(
+                  color: Theme.of(context).colorScheme.primaryContainer,
+                  child: page,
+                ),
+              ),
+            ],
+          ),
+        );
+      }
+    );
+  }
+}
+
+class FavoritesPage extends StatelessWidget {
+  const FavoritesPage({
+    super.key,
+  });
+
+  @override
+  Widget build(BuildContext context) {
+    var appState = context.watch<MyAppState>();
+
+    if (appState.favorites.isEmpty) {
+      return Center(
+        child: Text('No favorites yet.'),
+      );
+    }
+
+    return ListView(
+      children: [
+        Padding(
+          padding: const EdgeInsets.all(20),
+          child: Text('You have '
+              '${appState.favorites.length} favorites:'),
+        ),
+        for (var pair in appState.favorites)
+          ListTile(
+            leading: Icon(Icons.favorite),
+            title: Text(pair.asLowerCase),
+          ),
+      ],
+    );
+  }
+}
+
+class GeneratorPage extends StatelessWidget {
+  @override
+  Widget build(BuildContext context) {
+    var appState = context.watch<MyAppState>();
+    var pair = appState.current;
+
+    IconData icon;
+    if (appState.favorites.contains(pair)) {
+      icon = Icons.favorite;
+    } else {
+      icon = Icons.favorite_border;
+    }
+
+    return Center(
+      child: Column(
+        mainAxisAlignment: MainAxisAlignment.center,
+        children: [
+          BigCard(pair: pair),
+          SizedBox(height: 10),
+          Row(
+            mainAxisSize: MainAxisSize.min,
+            children: [
+              ElevatedButton.icon(
+                onPressed: () {
+                  appState.toggleFavorite();
+                },
+                icon: Icon(icon),
+                label: Text('Like'),
+              ),
+              SizedBox(width: 10),
+              ElevatedButton(
+                onPressed: () {
+                  appState.getNext();
+                },
+                child: Text('Next'),
+              ),
+            ],
+          ),
+        ],
+      ),
+    );
+  }
+}
+
+class BigCard extends StatelessWidget {
+  const BigCard({
+    super.key,
+    required this.pair,
+  });
+
+  final WordPair pair;
+
+  @override
+  Widget build(BuildContext context) {
+    final theme = Theme.of(context);
+    final style = theme.textTheme.displayMedium!.copyWith(
+      color: theme.colorScheme.onPrimary,
+    );
+
+    return Card(
+      color: theme.colorScheme.primary,
+      child: Padding(
+        padding: const EdgeInsets.all(15.0),
+        child: Text(
+          pair.asLowerCase,
+          style: style,
+          semanticsLabel: "${pair.first} ${pair.second}",
+        ),
+      ),
+    );
+  }
+}