Group the Sources tab by kind and pick a kind when adding a feed (#4)

The Sources tab shows News, Learning and Fun sections, each split by
language; kinds or languages without Sources get no header. The add-feed
dialog has a kind picker that defaults to News.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

README.md

@@ -34,7 +34,8 @@ or write a daily briefing. It's meant to replace the n8n → Discord workflow.
   valid for a day) and reuses the cookie for reader view and the in-app page.
   With it off, the app shows the teaser and an "Open website anyway" option.
 - **Sources**: 23 curated feeds (13 German, 10 English), toggle each one, or add any
-  RSS/Atom feed (it's validated before being added).
+  RSS/Atom feed as a News, Learning or Fun source (it's validated before being
+  added). The tab groups Sources by kind, then by language.
 - **Dark mode**: System / Light / Dark in Settings (applies instantly). The
   original-page view follows it too: when the phone is dark, sites use their own
   dark design or Android darkens them; when only the app is dark, the app inverts

lib/data/default_sources.dart

@@ -200,6 +200,18 @@ const defaultSources = <NewsSource>[
     language: SourceLanguage.en,
     description: 'Security and malware news',
   ),
+
+  // --- Learning -----------------------------------------------------------
+  NewsSource(
+    id: 'bytebytego',
+    name: 'ByteByteGo',
+    feedUrl: 'https://blog.bytebytego.com/feed',
+    homepage: 'https://blog.bytebytego.com',
+    language: SourceLanguage.en,
+    kind: SourceKind.learning,
+    description: 'System design explained with diagrams',
+    enabledByDefault: true,
+  ),
 ];
 
 /// The curated sources before the app remembered which ones it had seen.

lib/models/news_source.dart

@@ -8,6 +8,19 @@ enum SourceLanguage {
   final String flag;
 }
 
+/// What a Source's articles are for; see GLOSSARY.md. Each kind has its own
+/// section in the app and its own time window.
+enum SourceKind {
+  news('News'),
+  learning('Learning'),
+  fun('Fun');
+
+  const SourceKind(this.label);
+
+  final String label;
+}
+
+/// A Source of any [kind]; the class name predates the kinds.
 class NewsSource {
   const NewsSource({
     required this.id,
@@ -15,6 +28,7 @@ class NewsSource {
     required this.feedUrl,
     required this.homepage,
     required this.language,
+    this.kind = SourceKind.news,
     this.description = '',
     this.enabledByDefault = false,
     this.isCustom = false,
@@ -26,6 +40,7 @@ class NewsSource {
   final String feedUrl;
   final String homepage;
   final SourceLanguage language;
+  final SourceKind kind;
   final String description;
   final bool enabledByDefault;
   final bool isCustom;
@@ -40,6 +55,7 @@ class NewsSource {
         'feedUrl': feedUrl,
         'homepage': homepage,
         'language': language.name,
+        'kind': kind.name,
         'description': description,
       };
 
@@ -49,6 +65,8 @@ class NewsSource {
         feedUrl: json['feedUrl'] as String,
         homepage: json['homepage'] as String? ?? '',
         language: SourceLanguage.values.byName(json['language'] as String? ?? 'en'),
+        // Custom sources saved before kinds existed are News sources.
+        kind: SourceKind.values.asNameMap()[json['kind']] ?? SourceKind.news,
         description: json['description'] as String? ?? '',
         isCustom: true,
       );

lib/services/feed_service.dart

@@ -23,14 +23,15 @@ class FeedService {
 
   static const _timeout = Duration(seconds: 20);
 
-  /// Fetches all [sources] in parallel. Failing feeds are reported in
+  /// Fetches all [sources] in parallel and drops articles older than the age
+  /// [maxAgeOf] gives for their Source. Failing feeds are reported in
   /// [FeedResult.errors] instead of failing the whole refresh.
   ///
   /// [corsProxy] is only used on web, where browsers block cross-origin feed
   /// requests. It is prepended to the feed URL, e.g. `https://proxy/?url=`.
   Future<FeedResult> fetchAll(
     List<NewsSource> sources, {
-    required Duration maxAge,
+    required Duration Function(NewsSource source) maxAgeOf,
     String corsProxy = '',
   }) async {
     final errors = <String, String>{};
@@ -43,12 +44,15 @@ class FeedService {
       }
     }));
 
-    final cutoff = DateTime.now().toUtc().subtract(maxAge);
+    final now = DateTime.now().toUtc();
     final seen = <String>{};
     final articles = <Article>[
-      for (final list in results)
+      for (final (i, list) in results.indexed)
         for (final a in list)
-          if ((a.published == null || a.published!.isAfter(cutoff)) && seen.add(a.id)) a,
+          if ((a.published == null ||
+                  a.published!.isAfter(now.subtract(maxAgeOf(sources[i])))) &&
+              seen.add(a.id))
+            a,
     ];
     articles.sort((a, b) {
       final pa = a.published, pb = b.published;

lib/state/app_state.dart

@@ -34,8 +34,10 @@ class AppState extends ChangeNotifier {
     FeedService? feedService,
     ArticleExtractor? extractor,
     List<NewsSource> curatedSources = defaultSources,
+    Summarizer? summarizer,
   })  : _feeds = feedService ?? FeedService(),
         _curated = curatedSources,
+        _summarizerOverride = summarizer,
         consent = ConsentService(),
         paywall = PaywallService(_storage) {
     _extractor = extractor ?? ArticleExtractor(consent: consent);
@@ -46,6 +48,9 @@ class AppState extends ChangeNotifier {
 
   /// The curated catalog; [defaultSources] outside of tests.
   final List<NewsSource> _curated;
+
+  /// Used instead of the AI set up in [settings]; for tests.
+  final Summarizer? _summarizerOverride;
   late final ArticleExtractor _extractor;
   final PaywallService paywall;
 
@@ -56,7 +61,7 @@ class AppState extends ChangeNotifier {
   List<NewsSource> customSources = [];
   Set<String> enabledSourceIds = {};
 
-  /// Everything the feeds returned; see [visibleArticles] for what is shown.
+  /// Everything the feeds returned; see [articlesOf] for what is shown.
   List<Article> articles = [];
   Map<String, String> feedErrors = {};
   bool loading = false;
@@ -77,10 +82,22 @@ class AppState extends ChangeNotifier {
       (settings.hidePaid && paywall.isPaid(a)) ||
       (settings.hideSponsored && paywall.isSponsored(a));
 
-  /// Articles after the paid/sponsored filters. The feed and the briefing use these.
-  List<Article> get visibleArticles => articles.where((a) => !_isHidden(a)).toList();
+  /// Articles from Sources of [kind] after the paid/sponsored filters. Today
+  /// and the Briefing use News, the Learn tab the other kinds.
+  List<Article> articlesOf(SourceKind kind) =>
+      articles.where((a) => a.source.kind == kind && !_isHidden(a)).toList();
 
-  int get hiddenCount => articles.where(_isHidden).length;
+  /// Articles from Sources of [kind] that the paid/sponsored filters hide.
+  int hiddenCountOf(SourceKind kind) =>
+      articles.where((a) => a.source.kind == kind && _isHidden(a)).length;
+
+  /// How far back articles from Sources of [kind] reach. News follows the
+  /// user's setting; the other kinds age slower.
+  Duration windowOf(SourceKind kind) => switch (kind) {
+        SourceKind.news => Duration(hours: settings.maxAgeHours),
+        SourceKind.learning => const Duration(days: 14),
+        SourceKind.fun => const Duration(days: 3),
+      };
 
   List<NewsSource> get allSources => [..._curated, ...customSources];
 
@@ -102,7 +119,7 @@ class AppState extends ChangeNotifier {
     notifyListeners();
     final result = await _feeds.fetchAll(
       enabledSources,
-      maxAge: Duration(hours: settings.maxAgeHours),
+      maxAgeOf: (source) => windowOf(source.kind),
       corsProxy: settings.corsProxy,
     );
     articles = result.articles;
@@ -151,6 +168,7 @@ class AppState extends ChangeNotifier {
     required String name,
     required String feedUrl,
     required SourceLanguage language,
+    SourceKind kind = SourceKind.news,
   }) async {
     final uri = Uri.tryParse(feedUrl);
     final source = NewsSource(
@@ -159,6 +177,7 @@ class AppState extends ChangeNotifier {
       feedUrl: feedUrl,
       homepage: uri == null ? '' : '${uri.scheme}://${uri.host}',
       language: language,
+      kind: kind,
       isCustom: true,
     );
     try {
@@ -229,7 +248,7 @@ class AppState extends ChangeNotifier {
 
   // --- AI ------------------------------------------------------------------
 
-  Summarizer? get _summarizer => switch (settings.aiProvider) {
+  Summarizer? get _summarizer => _summarizerOverride ?? switch (settings.aiProvider) {
         _ when !settings.aiConfigured => null,
         AiProvider.claude => ClaudeSummarizer(
             apiKey: settings.claudeApiKey, model: settings.claudeModel),
@@ -273,7 +292,7 @@ class AppState extends ChangeNotifier {
   Future<void> generateBriefing() async {
     final summarizer = _summarizer;
     if (summarizer == null || briefingLoading) return;
-    final articles = visibleArticles;
+    final articles = articlesOf(SourceKind.news);
     if (articles.isEmpty) {
       briefingError = 'No articles loaded yet. Pull to refresh the feed first.';
       notifyListeners();

lib/ui/briefing_screen.dart

@@ -1,6 +1,7 @@
 import 'package:flutter/material.dart';
 
 import '../models/briefing.dart';
+import '../models/news_source.dart';
 import '../state/app_state.dart';
 import 'article_screen.dart';
 import 'briefing_history_screen.dart';
@@ -59,7 +60,7 @@ class BriefingScreen extends StatelessWidget {
     if (state.briefingLoading) {
       return EmptyState(
         icon: Icons.hourglass_top,
-        title: 'Reading ${state.visibleArticles.length} headlines…',
+        title: 'Reading ${state.articlesOf(SourceKind.news).length} headlines…',
         message: 'This usually takes 10-60 seconds.',
         action: const SizedBox(width: 160, child: LinearProgressIndicator()),
       );
@@ -69,7 +70,7 @@ class BriefingScreen extends StatelessWidget {
       icon: const Icon(Icons.auto_awesome),
       label: Text(state.loading
           ? 'Waiting for feeds…'
-          : 'Generate from ${state.visibleArticles.length} articles'),
+          : 'Generate from ${state.articlesOf(SourceKind.news).length} articles'),
     );
     if (briefing == null) {
       return EmptyState(

lib/ui/feed_screen.dart

@@ -25,13 +25,13 @@ class _FeedScreenState extends State<FeedScreen> {
       listenable: widget.state,
       builder: (context, _) {
         final state = widget.state;
-        final all = state.visibleArticles;
+        final all = state.articlesOf(SourceKind.news);
         final visible = all
             .where((a) => _language == null || a.source.language == _language)
             .where((a) => _sourceId == null || a.source.id == _sourceId)
             .toList();
         final sourcesInFeed = {for (final a in all) a.source.id: a.source};
-        final hidden = state.hiddenCount;
+        final hidden = state.hiddenCountOf(SourceKind.news);
 
         return Scaffold(
           appBar: AppBar(

lib/ui/home_shell.dart

@@ -3,9 +3,13 @@ import 'package:flutter/material.dart';
 import '../state/app_state.dart';
 import 'briefing_screen.dart';
 import 'feed_screen.dart';
+import 'learn_screen.dart';
 import 'settings_screen.dart';
 import 'sources_screen.dart';
 
+/// The tabs in the order they appear in the navigation bar.
+enum _Tab { today, briefing, learn, sources, settings }
+
 class HomeShell extends StatefulWidget {
   const HomeShell({super.key, required this.state});
 
@@ -16,20 +20,20 @@ class HomeShell extends StatefulWidget {
 }
 
 class _HomeShellState extends State<HomeShell> {
-  int _index = 0;
+  _Tab _tab = _Tab.today;
   bool _sourcesChanged = false;
 
-  void _select(int index) {
+  void _select(_Tab tab) {
     // A text field left focused in Settings would otherwise get focus back
     // (and open the keyboard) when returning from an article.
     FocusManager.instance.primaryFocus?.unfocus();
     // Source toggles only take effect on the next refresh; do it when the
     // user leaves the Sources tab.
-    if (_index == 2 && index != 2 && _sourcesChanged) {
+    if (_tab == _Tab.sources && tab != _Tab.sources && _sourcesChanged) {
       _sourcesChanged = false;
       widget.state.refresh();
     }
-    setState(() => _index = index);
+    setState(() => _tab = tab);
   }
 
   @override
@@ -37,20 +41,27 @@ class _HomeShellState extends State<HomeShell> {
     final state = widget.state;
     return Scaffold(
       body: IndexedStack(
-        index: _index,
+        index: _tab.index,
         children: [
-          FeedScreen(state: state),
-          BriefingScreen(state: state, openSettings: () => _select(3)),
-          SourcesScreen(state: state, onChanged: () => _sourcesChanged = true),
-          SettingsScreen(state: state),
-        ].indexed
+          for (final tab in _Tab.values)
             // Hidden tabs stay alive but must not hold or regain focus.
-            .map((e) => ExcludeFocus(excluding: e.$1 != _index, child: e.$2))
-            .toList(),
+            ExcludeFocus(
+              excluding: tab != _tab,
+              child: switch (tab) {
+                _Tab.today => FeedScreen(state: state),
+                _Tab.briefing => BriefingScreen(
+                    state: state, openSettings: () => _select(_Tab.settings)),
+                _Tab.learn => LearnScreen(state: state),
+                _Tab.sources =>
+                  SourcesScreen(state: state, onChanged: () => _sourcesChanged = true),
+                _Tab.settings => SettingsScreen(state: state),
+              },
+            ),
+        ],
       ),
       bottomNavigationBar: NavigationBar(
-        selectedIndex: _index,
-        onDestinationSelected: _select,
+        selectedIndex: _tab.index,
+        onDestinationSelected: (i) => _select(_Tab.values[i]),
         destinations: const [
           NavigationDestination(
               icon: Icon(Icons.newspaper_outlined),
@@ -60,6 +71,10 @@ class _HomeShellState extends State<HomeShell> {
               icon: Icon(Icons.auto_awesome_outlined),
               selectedIcon: Icon(Icons.auto_awesome),
               label: 'Briefing'),
+          NavigationDestination(
+              icon: Icon(Icons.school_outlined),
+              selectedIcon: Icon(Icons.school),
+              label: 'Learn'),
           NavigationDestination(
               icon: Icon(Icons.rss_feed_outlined),
               selectedIcon: Icon(Icons.rss_feed),

lib/ui/learn_screen.dart

@@ -0,0 +1,98 @@
+import 'package:flutter/material.dart';
+
+import '../models/news_source.dart';
+import '../state/app_state.dart';
+import 'article_screen.dart';
+import 'feed_screen.dart';
+
+/// Reading that keeps for days, from the Sources that aren't News: one
+/// section per kind, each with its own time window.
+class LearnScreen extends StatelessWidget {
+  const LearnScreen({super.key, required this.state});
+
+  final AppState state;
+
+  /// The sections, top to bottom.
+  static const kinds = [SourceKind.learning];
+
+  @override
+  Widget build(BuildContext context) {
+    return ListenableBuilder(
+      listenable: state,
+      builder: (context, _) => Scaffold(
+        appBar: AppBar(
+          title: const Text('Learn'),
+          actions: [
+            IconButton(
+              tooltip: 'Refresh',
+              onPressed: state.loading ? null : state.refresh,
+              icon: const Icon(Icons.refresh),
+            ),
+          ],
+        ),
+        body: Column(
+          children: [
+            if (state.loading) const LinearProgressIndicator(),
+            Expanded(
+              child: RefreshIndicator(
+                onRefresh: state.refresh,
+                child: ListView(
+                  padding: const EdgeInsets.fromLTRB(12, 0, 12, 24),
+                  children: [for (final kind in kinds) ..._section(context, kind)],
+                ),
+              ),
+            ),
+          ],
+        ),
+      ),
+    );
+  }
+
+  List<Widget> _section(BuildContext context, SourceKind kind) {
+    final theme = Theme.of(context);
+    final muted = theme.colorScheme.onSurfaceVariant;
+    final articles = state.articlesOf(kind);
+    final hidden = state.hiddenCountOf(kind);
+    final hasSources = state.enabledSources.any((s) => s.kind == kind);
+    return [
+      Padding(
+        padding: const EdgeInsets.fromLTRB(4, 16, 4, 8),
+        child: Column(
+          crossAxisAlignment: CrossAxisAlignment.start,
+          children: [
+            Text(kind.label,
+                style: theme.textTheme.titleMedium?.copyWith(color: theme.colorScheme.primary)),
+            Text(
+              '${articles.length} articles · last ${_describe(state.windowOf(kind))}'
+              '${hidden > 0 ? ' · $hidden paid/ads hidden' : ''}',
+              style: theme.textTheme.bodySmall?.copyWith(color: muted),
+            ),
+          ],
+        ),
+      ),
+      if (articles.isEmpty && !state.loading)
+        Padding(
+          padding: const EdgeInsets.fromLTRB(4, 8, 4, 16),
+          child: Text(
+            hasSources
+                ? 'Nothing new in this window. Pull down to refresh.'
+                : 'No ${kind.label} sources enabled. Turn some on in the Sources tab.',
+            style: theme.textTheme.bodyMedium?.copyWith(color: muted),
+          ),
+        ),
+      for (final article in articles)
+        Padding(
+          padding: const EdgeInsets.only(bottom: 8),
+          child: ArticleCard(
+            article: article,
+            hasSummary: state.summaries[article.id]?.text != null,
+            isPaid: state.paywall.isPaid(article),
+            onTap: () => openArticle(context, state, article),
+          ),
+        ),
+    ];
+  }
+
+  static String _describe(Duration window) =>
+      window.inHours < 72 ? '${window.inHours} h' : '${window.inDays} days';
+}

lib/ui/sources_screen.dart

@@ -40,29 +40,7 @@ class SourcesScreen extends StatelessWidget {
           body: ListView(
             padding: const EdgeInsets.only(bottom: 96),
             children: [
-              for (final lang in SourceLanguage.values) ...[
-                Padding(
-                  padding: const EdgeInsets.fromLTRB(16, 16, 16, 4),
-                  child: Text('${lang.flag}  ${lang.label}',
-                      style: theme.textTheme.titleSmall
-                          ?.copyWith(color: theme.colorScheme.primary)),
-                ),
-                for (final source in state.allSources.where((s) => s.language == lang))
-                  _SourceTile(
-                    source: source,
-                    enabled: state.enabledSourceIds.contains(source.id),
-                    onToggle: (v) {
-                      state.setSourceEnabled(source, v);
-                      onChanged();
-                    },
-                    onDelete: source.isCustom
-                        ? () {
-                            state.removeCustomSource(source);
-                            onChanged();
-                          }
-                        : null,
-                  ),
-              ],
+              for (final kind in SourceKind.values) ..._kindSection(context, kind),
             ],
           ),
         );
@@ -70,6 +48,44 @@ class SourcesScreen extends StatelessWidget {
     );
   }
 
+  /// One section per kind, split by language. Kinds and languages without
+  /// Sources are left out instead of showing an empty header.
+  List<Widget> _kindSection(BuildContext context, SourceKind kind) {
+    final theme = Theme.of(context);
+    final sources = state.allSources.where((s) => s.kind == kind).toList();
+    if (sources.isEmpty) return const [];
+    return [
+      Padding(
+        padding: const EdgeInsets.fromLTRB(16, 24, 16, 0),
+        child: Text(kind.label, style: theme.textTheme.titleMedium),
+      ),
+      for (final lang in SourceLanguage.values)
+        if (sources.any((s) => s.language == lang)) ...[
+          Padding(
+            padding: const EdgeInsets.fromLTRB(16, 12, 16, 4),
+            child: Text('${lang.flag}  ${lang.label}',
+                style: theme.textTheme.titleSmall
+                    ?.copyWith(color: theme.colorScheme.primary)),
+          ),
+          for (final source in sources.where((s) => s.language == lang))
+            _SourceTile(
+              source: source,
+              enabled: state.enabledSourceIds.contains(source.id),
+              onToggle: (v) {
+                state.setSourceEnabled(source, v);
+                onChanged();
+              },
+              onDelete: source.isCustom
+                  ? () {
+                      state.removeCustomSource(source);
+                      onChanged();
+                    }
+                  : null,
+            ),
+        ],
+    ];
+  }
+
   Future<void> _addFeed(BuildContext context) async {
     final added = await showDialog<bool>(
       context: context,
@@ -134,6 +150,7 @@ class _AddFeedDialogState extends State<_AddFeedDialog> {
   final _name = TextEditingController();
   final _url = TextEditingController();
   SourceLanguage _language = SourceLanguage.de;
+  SourceKind _kind = SourceKind.news;
   bool _busy = false;
   String? _error;
 
@@ -156,7 +173,7 @@ class _AddFeedDialogState extends State<_AddFeedDialog> {
       _error = null;
     });
     final error = await widget.state
-        .addCustomSource(name: name, feedUrl: url, language: _language);
+        .addCustomSource(name: name, feedUrl: url, language: _language, kind: _kind);
     if (!mounted) return;
     if (error == null) {
       Navigator.pop(context, true);
@@ -199,6 +216,15 @@ class _AddFeedDialogState extends State<_AddFeedDialog> {
               selected: {_language},
               onSelectionChanged: (s) => setState(() => _language = s.first),
             ),
+            const SizedBox(height: 12),
+            SegmentedButton<SourceKind>(
+              segments: [
+                for (final k in SourceKind.values)
+                  ButtonSegment(value: k, label: Text(k.label)),
+              ],
+              selected: {_kind},
+              onSelectionChanged: (s) => setState(() => _kind = s.first),
+            ),
             if (_error != null) ...[
               const SizedBox(height: 12),
               Text(_error!, style: TextStyle(color: Theme.of(context).colorScheme.error)),

test/default_sources_test.dart

@@ -8,7 +8,7 @@ void main() {
   test('the News sources on by default are the curated quality set', () {
     final onByDefault = {
       for (final s in defaultSources)
-        if (s.enabledByDefault) s.id,
+        if (s.enabledByDefault && s.kind == SourceKind.news) s.id,
     };
 
     expect(onByDefault, {

test/learn_tab_test.dart

@@ -0,0 +1,92 @@
+import 'package:daily_tech_news/models/news_source.dart';
+import 'package:daily_tech_news/state/app_state.dart';
+import 'package:daily_tech_news/ui/feed_screen.dart';
+import 'package:daily_tech_news/ui/home_shell.dart';
+import 'package:daily_tech_news/ui/learn_screen.dart';
+import 'package:daily_tech_news/ui/settings_screen.dart';
+import 'package:flutter/material.dart';
+import 'package:flutter_test/flutter_test.dart';
+import 'package:shared_preferences/shared_preferences.dart';
+
+import 'support/fake_app.dart';
+
+void main() {
+  final verge = testSource('verge', SourceKind.news);
+  final bytebytego = testSource('bytebytego', SourceKind.learning);
+  final feeds = {
+    verge.feedUrl: [('News from this morning', const Duration(hours: 2))],
+    bytebytego.feedUrl: [('Explainer from 13 days ago', const Duration(days: 13)),
+      ('Explainer from 2 days ago', const Duration(days: 2))],
+  };
+
+  setUp(() => SharedPreferences.setMockInitialValues({}));
+
+  Future<AppState> launch(WidgetTester tester, [FakeFeeds? feedService]) async =>
+      (await tester.runAsync(() => launchApp([verge, bytebytego],
+          feedService: feedService ?? FakeFeeds(feeds))))!;
+
+  Finder tab(String label) =>
+      find.descendant(of: find.byType(NavigationBar), matching: find.text(label));
+
+  testWidgets('the Learn tab lists Learning articles newest first, without News',
+      (tester) async {
+    final state = await launch(tester);
+
+    await tester.pumpWidget(MaterialApp(home: LearnScreen(state: state)));
+
+    final newer = find.text('Explainer from 2 days ago');
+    final older = find.text('Explainer from 13 days ago');
+    expect(newer, findsOneWidget);
+    expect(older, findsOneWidget);
+    expect(tester.getTopLeft(newer).dy, lessThan(tester.getTopLeft(older).dy));
+    expect(find.text('News from this morning'), findsNothing);
+  });
+
+  testWidgets('Today lists News without Learning articles', (tester) async {
+    final state = await launch(tester);
+
+    await tester.pumpWidget(MaterialApp(home: FeedScreen(state: state)));
+
+    expect(find.text('News from this morning'), findsOneWidget);
+    expect(find.text('Explainer from 2 days ago'), findsNothing);
+  });
+
+  testWidgets('the tabs are Today, Briefing, Learn, Sources and Settings', (tester) async {
+    final state = await launch(tester);
+
+    await tester.pumpWidget(MaterialApp(home: HomeShell(state: state)));
+
+    final labels = ['Today', 'Briefing', 'Learn', 'Sources', 'Settings'];
+    final xs = [for (final label in labels) tester.getCenter(tab(label)).dx];
+    expect(xs, [...xs]..sort());
+  });
+
+  testWidgets('Open Settings on the Briefing tab goes to Settings', (tester) async {
+    final state = await launch(tester);
+    await tester.pumpWidget(MaterialApp(home: HomeShell(state: state)));
+
+    await tester.tap(tab('Briefing'));
+    await tester.pump();
+    await tester.tap(find.text('Open Settings'));
+    await tester.pump();
+
+    expect(find.byType(SettingsScreen), findsOneWidget);
+  });
+
+  testWidgets('leaving the Sources tab after a change refreshes the feeds', (tester) async {
+    final feedService = FakeFeeds(feeds);
+    final state = await launch(tester, feedService);
+    await tester.pumpWidget(MaterialApp(home: HomeShell(state: state)));
+    final before = feedService.refreshes;
+
+    await tester.tap(tab('Sources'));
+    await tester.pump();
+    await tester.tap(find.text('verge'));
+    await tester.pump();
+    expect(feedService.refreshes, before);
+
+    await tester.tap(tab('Learn'));
+    await tester.pump();
+    expect(feedService.refreshes, before + 1);
+  });
+}

test/source_kinds_test.dart

@@ -0,0 +1,138 @@
+import 'dart:convert';
+
+import 'package:daily_tech_news/data/default_sources.dart';
+import 'package:daily_tech_news/models/article.dart';
+import 'package:daily_tech_news/models/briefing.dart';
+import 'package:daily_tech_news/models/news_source.dart';
+import 'package:daily_tech_news/services/summarizer.dart';
+import 'package:flutter_test/flutter_test.dart';
+import 'package:shared_preferences/shared_preferences.dart';
+
+import 'support/fake_app.dart';
+
+/// Remembers which articles a Briefing was asked for.
+class _RecordingSummarizer implements Summarizer {
+  List<Article>? briefingInput;
+
+  @override
+  String get name => 'test';
+
+  @override
+  Future<String> summarizeArticle(Article article, String text, SourceLanguage language) async =>
+      '';
+
+  @override
+  Future<DailyBriefing> createBriefing(List<Article> articles, SourceLanguage language) async {
+    briefingInput = articles;
+    return DailyBriefing(createdAt: DateTime.now(), intro: '', topics: const [], generatedBy: name);
+  }
+}
+
+List<String> _titles(List<Article> articles) => articles.map((a) => a.title).toList();
+
+void main() {
+  final verge = testSource('verge', SourceKind.news);
+  final bytebytego = testSource('bytebytego', SourceKind.learning);
+
+  setUp(() => SharedPreferences.setMockInitialValues({}));
+
+  test('News uses the 24 h setting and Learning reaches back 14 days', () async {
+    final state = await launchApp([verge, bytebytego], feeds: {
+      verge.feedUrl: [('News from this morning', const Duration(hours: 2)),
+        ('News from yesterday', const Duration(hours: 30))],
+      bytebytego.feedUrl: [('Explainer from 2 days ago', const Duration(days: 2)),
+        ('Explainer from 13 days ago', const Duration(days: 13)),
+        ('Explainer from 15 days ago', const Duration(days: 15))],
+    });
+
+    expect(_titles(state.articlesOf(SourceKind.news)), ['News from this morning']);
+    expect(_titles(state.articlesOf(SourceKind.learning)),
+        ['Explainer from 2 days ago', 'Explainer from 13 days ago']);
+  });
+
+  test('the Briefing is generated from News articles only', () async {
+    final summarizer = _RecordingSummarizer();
+    final state = await launchApp([verge, bytebytego], feeds: {
+      verge.feedUrl: [('News from this morning', const Duration(hours: 2))],
+      bytebytego.feedUrl: [('Explainer from today', const Duration(hours: 1))],
+    }, summarizer: summarizer);
+
+    await state.generateBriefing();
+
+    expect(_titles(summarizer.briefingInput!), ['News from this morning']);
+  });
+
+  test('News follows the window setting', () async {
+    SharedPreferences.setMockInitialValues({'max_age_hours': 48});
+    final state = await launchApp([verge], feeds: {
+      verge.feedUrl: [('News from yesterday', const Duration(hours: 30)),
+        ('News from 3 days ago', const Duration(hours: 72))],
+    });
+
+    expect(_titles(state.articlesOf(SourceKind.news)), ['News from yesterday']);
+  });
+
+  test('Fun reaches back 3 days', () async {
+    final xkcd = testSource('xkcd', SourceKind.fun);
+    final state = await launchApp([xkcd], feeds: {
+      xkcd.feedUrl: [('Comic from 2 days ago', const Duration(days: 2)),
+        ('Comic from 4 days ago', const Duration(days: 4))],
+    });
+
+    expect(_titles(state.articlesOf(SourceKind.fun)), ['Comic from 2 days ago']);
+  });
+
+  test('custom Sources saved before kinds existed load as News', () async {
+    SharedPreferences.setMockInitialValues({
+      'custom_sources': jsonEncode([
+        {'id': 'custom-1', 'name': 'My blog', 'feedUrl': 'https://blog.example.com/feed',
+          'homepage': 'https://blog.example.com', 'language': 'de', 'description': ''},
+      ]),
+    });
+
+    final state = await launchApp([verge]);
+
+    expect(state.customSources.single.kind, SourceKind.news);
+  });
+
+  test('a custom Learning source is still a Learning source after a restart', () async {
+    final before = await launchApp([verge]);
+    await before.addCustomSource(
+      name: 'Engineering blog',
+      feedUrl: 'https://eng.example.com/feed',
+      language: SourceLanguage.en,
+      kind: SourceKind.learning,
+    );
+
+    final after = await launchApp([verge]);
+
+    expect(after.customSources.single.name, 'Engineering blog');
+    expect(after.customSources.single.kind, SourceKind.learning);
+  });
+
+  test('paid and sponsored Learning articles are hidden like News ones', () async {
+    final state = await launchApp([bytebytego], feeds: {
+      bytebytego.feedUrl: [('How DNS works', const Duration(days: 1)),
+        ('Sponsored: Try our database', const Duration(days: 1))],
+    });
+
+    expect(_titles(state.articlesOf(SourceKind.learning)), ['How DNS works']);
+    expect(state.hiddenCountOf(SourceKind.learning), 1);
+  });
+
+  test('every curated Source from before kinds is a News source', () {
+    final older = defaultSources.where((s) => legacySeenSourceIds.contains(s.id));
+
+    expect(older, isNotEmpty);
+    expect(older.where((s) => s.kind != SourceKind.news), isEmpty);
+  });
+
+  test('ByteByteGo is a Learning source that is on by default', () {
+    final bytebytego = defaultSources.singleWhere((s) => s.name == 'ByteByteGo');
+
+    expect(bytebytego.kind, SourceKind.learning);
+    expect(bytebytego.feedUrl, 'https://blog.bytebytego.com/feed');
+    expect(bytebytego.language, SourceLanguage.en);
+    expect(bytebytego.enabledByDefault, isTrue);
+  });
+}

test/source_selection_test.dart

@@ -10,7 +10,7 @@ import 'package:shared_preferences/shared_preferences.dart';
 class _NoFeeds extends FeedService {
   @override
   Future<FeedResult> fetchAll(List<NewsSource> sources,
-          {required Duration maxAge, String corsProxy = ''}) async =>
+          {required Duration Function(NewsSource source) maxAgeOf, String corsProxy = ''}) async =>
       const FeedResult([], {});
 }
 
@@ -87,7 +87,7 @@ void main() {
     expect(state.enabledSourceIds, {
       'heise', 'verge', 'mit-tr', 'new-source',
       // Added to the catalog later, on by default.
-      'techmeme', 'lobsters', 'the-decoder', 'simonwillison',
+      'techmeme', 'lobsters', 'the-decoder', 'simonwillison', 'bytebytego',
     });
   });
 
@@ -102,7 +102,7 @@ void main() {
 
     expect(state.enabledSourceIds, {
       'heise', 'golem', 't3n', 'verge',
-      'techmeme', 'lobsters', 'the-decoder', 'simonwillison',
+      'techmeme', 'lobsters', 'the-decoder', 'simonwillison', 'bytebytego',
     });
     expect(state.enabledSources.map((s) => s.id), isNot(contains('wired')));
   });

test/sources_tab_test.dart

@@ -0,0 +1,153 @@
+import 'package:daily_tech_news/models/news_source.dart';
+import 'package:daily_tech_news/state/app_state.dart';
+import 'package:daily_tech_news/ui/home_shell.dart';
+import 'package:daily_tech_news/ui/sources_screen.dart';
+import 'package:flutter/material.dart';
+import 'package:flutter_test/flutter_test.dart';
+import 'package:shared_preferences/shared_preferences.dart';
+
+import 'support/fake_app.dart';
+
+NewsSource _source(String id, SourceKind kind, SourceLanguage language) => NewsSource(
+      id: id,
+      name: id,
+      feedUrl: 'https://example.com/$id.xml',
+      homepage: 'https://example.com',
+      language: language,
+      kind: kind,
+      enabledByDefault: true,
+    );
+
+void main() {
+  final heise = _source('heise', SourceKind.news, SourceLanguage.de);
+  final verge = _source('verge', SourceKind.news, SourceLanguage.en);
+  final bytebytego = _source('bytebytego', SourceKind.learning, SourceLanguage.en);
+  final xkcd = _source('xkcd', SourceKind.fun, SourceLanguage.en);
+
+  const german = '🇩🇪  Deutsch';
+  const english = '🇬🇧  English';
+
+  setUp(() => SharedPreferences.setMockInitialValues({}));
+
+  Future<AppState> launch(WidgetTester tester, List<NewsSource> sources) async =>
+      (await tester.runAsync(() => launchApp(sources)))!;
+
+  Future<void> showSources(WidgetTester tester, AppState state) async {
+    tester.view.physicalSize = const Size(800, 2400);
+    tester.view.devicePixelRatio = 1;
+    addTearDown(tester.view.reset);
+    await tester.pumpWidget(
+        MaterialApp(home: SourcesScreen(state: state, onChanged: () {})));
+  }
+
+  /// Asserts the [finders] each match once on screen, from top to bottom.
+  void expectInOrder(WidgetTester tester, List<Finder> finders) {
+    final ys = [for (final f in finders) tester.getTopLeft(f).dy];
+    expect(ys, [...ys]..sort());
+    expect(ys.toSet().length, ys.length);
+  }
+
+  testWidgets('the Sources tab groups News, Learning and Fun, each split by language',
+      (tester) async {
+    final state = await launch(tester, [xkcd, bytebytego, verge, heise]);
+
+    await showSources(tester, state);
+
+    expectInOrder(tester, [
+      find.text('News'),
+      find.text(german).at(0),
+      find.text('heise'),
+      find.text(english).at(0),
+      find.text('verge'),
+      find.text('Learning'),
+      find.text(english).at(1),
+      find.text('bytebytego'),
+      find.text('Fun'),
+      find.text(english).at(2),
+      find.text('xkcd'),
+    ]);
+  });
+
+  testWidgets('a kind without Sources gets no section', (tester) async {
+    final state = await launch(tester, [verge]);
+
+    await showSources(tester, state);
+
+    expect(find.text('News'), findsOneWidget);
+    expect(find.text('Learning'), findsNothing);
+    expect(find.text('Fun'), findsNothing);
+    expect(find.text(german), findsNothing);
+  });
+
+  Future<void> addFeed(WidgetTester tester, String name, {String? kind}) async {
+    await tester.tap(find.text('Add feed'));
+    await tester.pumpAndSettle();
+    final dialog = find.byType(AlertDialog);
+    await tester.enterText(
+        find.descendant(of: dialog, matching: find.widgetWithText(TextField, 'Name')), name);
+    await tester.enterText(
+        find.descendant(of: dialog, matching: find.widgetWithText(TextField, 'Feed URL')),
+        'https://example.com/$name.xml');
+    if (kind != null) {
+      await tester.tap(find.descendant(of: dialog, matching: find.text(kind)));
+      await tester.pump();
+    }
+    await tester.tap(find.descendant(of: dialog, matching: find.text('Add')));
+    await tester.pumpAndSettle();
+  }
+
+  testWidgets('a feed added without picking a kind is a News source', (tester) async {
+    final state = await launch(tester, [verge, bytebytego]);
+    await showSources(tester, state);
+
+    await addFeed(tester, 'myfeed');
+
+    expectInOrder(tester, [find.text('News'), find.text('myfeed'), find.text('Learning')]);
+  });
+
+  testWidgets('a feed added as Learning shows up in the Learning section', (tester) async {
+    final state = await launch(tester, [verge, bytebytego]);
+    await showSources(tester, state);
+
+    await addFeed(tester, 'myblog', kind: 'Learning');
+
+    expectInOrder(tester, [find.text('Learning'), find.text('myblog')]);
+  });
+
+  testWidgets('a feed added as Fun gets a Fun section', (tester) async {
+    final state = await launch(tester, [verge]);
+    await showSources(tester, state);
+
+    await addFeed(tester, 'mycomic', kind: 'Fun');
+
+    expectInOrder(tester, [find.text('News'), find.text('Fun'), find.text('mycomic')]);
+  });
+
+  testWidgets('a custom Learning source shows up in the Learn tab, not in Today',
+      (tester) async {
+    final feeds = FakeFeeds({
+      verge.feedUrl: [('News from this morning', const Duration(hours: 2))],
+      'https://example.com/myblog.xml': [('Explainer from my blog', const Duration(days: 2))],
+    });
+    final state = (await tester.runAsync(() => launchApp([verge], feedService: feeds)))!;
+    tester.view.physicalSize = const Size(800, 2400);
+    tester.view.devicePixelRatio = 1;
+    addTearDown(tester.view.reset);
+    await tester.pumpWidget(MaterialApp(home: HomeShell(state: state)));
+    Finder tab(String label) =>
+        find.descendant(of: find.byType(NavigationBar), matching: find.text(label));
+
+    await tester.tap(tab('Sources'));
+    await tester.pump();
+    await addFeed(tester, 'myblog', kind: 'Learning');
+    await tester.tap(tab('Learn'));
+    await tester.pumpAndSettle();
+
+    expect(find.text('Explainer from my blog'), findsOneWidget);
+
+    await tester.tap(tab('Today'));
+    await tester.pumpAndSettle();
+    expect(find.text('News from this morning'), findsOneWidget);
+    expect(find.text('Explainer from my blog'), findsNothing);
+  });
+}

test/support/fake_app.dart

@@ -0,0 +1,68 @@
+import 'package:daily_tech_news/models/article.dart';
+import 'package:daily_tech_news/models/news_source.dart';
+import 'package:daily_tech_news/services/feed_service.dart';
+import 'package:daily_tech_news/services/storage.dart';
+import 'package:daily_tech_news/services/summarizer.dart';
+import 'package:daily_tech_news/state/app_state.dart';
+
+/// Serves canned articles per Source instead of the network. The real
+/// [FeedService.fetchAll] still applies the time windows.
+class FakeFeeds extends FeedService {
+  FakeFeeds([this.byFeedUrl = const {}]);
+
+  /// Feed URL -> (title, age) of each article in the feed.
+  final Map<String, List<(String, Duration)>> byFeedUrl;
+
+  /// How often the app refreshed its feeds.
+  int refreshes = 0;
+
+  @override
+  Future<FeedResult> fetchAll(List<NewsSource> sources,
+      {required Duration Function(NewsSource source) maxAgeOf, String corsProxy = ''}) {
+    refreshes++;
+    return super.fetchAll(sources, maxAgeOf: maxAgeOf, corsProxy: corsProxy);
+  }
+
+  @override
+  Future<List<Article>> fetchSource(NewsSource source, {String corsProxy = ''}) async {
+    final now = DateTime.now().toUtc();
+    // A feed nobody set up still has an article, so it can be added.
+    if (!byFeedUrl.containsKey(source.feedUrl)) {
+      return [Article(title: 'Any', link: '${source.feedUrl}#any', source: source)];
+    }
+    return [
+      for (final (title, age) in byFeedUrl[source.feedUrl]!)
+        Article(
+          title: title,
+          link: '${source.feedUrl}#$title',
+          source: source,
+          published: now.subtract(age),
+        ),
+    ];
+  }
+}
+
+NewsSource testSource(String id, SourceKind kind) => NewsSource(
+      id: id,
+      name: id,
+      feedUrl: 'https://example.com/$id.xml',
+      homepage: 'https://example.com',
+      language: SourceLanguage.en,
+      kind: kind,
+      enabledByDefault: true,
+    );
+
+/// Starts the app the way a launch does, against whatever is in preferences.
+Future<AppState> launchApp(
+  List<NewsSource> curatedSources, {
+  Map<String, List<(String, Duration)>> feeds = const {},
+  FeedService? feedService,
+  Summarizer? summarizer,
+}) async {
+  final state = AppState(await Storage.open(),
+      feedService: feedService ?? FakeFeeds(feeds),
+      curatedSources: curatedSources,
+      summarizer: summarizer);
+  await state.init();
+  return state;
+}