Switch newly added default Sources on once (#1)

The app now remembers which curated Sources it has seen. A Source that is on
by default is enabled the first time it appears, also on installs with saved
toggles; Sources seen before keep the user's choice. Installs from before this
change count the current catalog as seen.

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

lib/state/app_state.dart

@@ -29,8 +29,13 @@ class SummaryState {
 }
 
 class AppState extends ChangeNotifier {
-  AppState(this._storage, {FeedService? feedService, ArticleExtractor? extractor})
-      : _feeds = feedService ?? FeedService(),
+  AppState(
+    this._storage, {
+    FeedService? feedService,
+    ArticleExtractor? extractor,
+    List<NewsSource> curatedSources = defaultSources,
+  })  : _feeds = feedService ?? FeedService(),
+        _curated = curatedSources,
         consent = ConsentService(),
         paywall = PaywallService(_storage) {
     _extractor = extractor ?? ArticleExtractor(consent: consent);
@@ -38,6 +43,9 @@ class AppState extends ChangeNotifier {
 
   final Storage _storage;
   final FeedService _feeds;
+
+  /// The curated catalog; [defaultSources] outside of tests.
+  final List<NewsSource> _curated;
   late final ArticleExtractor _extractor;
   final PaywallService paywall;
 
@@ -74,7 +82,7 @@ class AppState extends ChangeNotifier {
 
   int get hiddenCount => articles.where(_isHidden).length;
 
-  List<NewsSource> get allSources => [...defaultSources, ...customSources];
+  List<NewsSource> get allSources => [..._curated, ...customSources];
 
   List<NewsSource> get enabledSources =>
       allSources.where((s) => enabledSourceIds.contains(s.id)).toList();
@@ -82,8 +90,7 @@ class AppState extends ChangeNotifier {
   Future<void> init() async {
     settings = await _storage.loadSettings();
     customSources = _storage.loadCustomSources();
-    enabledSourceIds = _storage.loadEnabledSourceIds() ??
-        defaultSources.where((s) => s.enabledByDefault).map((s) => s.id).toSet();
+    await _enableNewDefaultSources();
     briefings = await _storage.loadBriefingHistory();
     notifyListeners();
     await refresh();
@@ -111,6 +118,24 @@ class AppState extends ChangeNotifier {
 
   // --- Sources -------------------------------------------------------------
 
+  /// Switches on curated sources that are on by default the first time the
+  /// app sees them, so they also reach installs with saved toggles. Sources
+  /// seen before keep whatever the user chose.
+  Future<void> _enableNewDefaultSources() async {
+    final saved = _storage.loadEnabledSourceIds();
+    final seen = _storage.loadSeenSourceIds() ??
+        (saved == null ? const <String>{} : legacySeenSourceIds);
+    final unseen = _curated.where((s) => !seen.contains(s.id)).toList();
+    enabledSourceIds = {
+      ...?saved,
+      for (final s in unseen)
+        if (s.enabledByDefault) s.id,
+    };
+    if (unseen.isEmpty) return;
+    await _storage.saveSeenSourceIds({...seen, ...unseen.map((s) => s.id)});
+    await _storage.saveEnabledSourceIds(enabledSourceIds);
+  }
+
   Future<void> setSourceEnabled(NewsSource source, bool enabled) async {
     enabled ? enabledSourceIds.add(source.id) : enabledSourceIds.remove(source.id);
     notifyListeners();