Keep per-kind facts on SourceKind and the Briefing's input in one place (review items 4, 5, 6, 7)

- SourceKind carries whether it feeds the Briefing, its fixed time window
  (Learning, Fun) and whether reading is picture-led (Fun); windowOf and
  the reader read from it.
- AppState.briefingArticles is the one place that says only News sources
  feed the Briefing; generateBriefing and the Briefing tab use it.
- articlesOf, hiddenCountOf and briefingArticles share one filter.
- FeedService.fetchAll takes windowOf: like AppState.windowOf.

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

lib/models/source.dart

@@ -11,13 +11,28 @@ enum SourceLanguage {
 /// 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');
+  news('News', feedsBriefing: true),
+  learning('Learning', fixedWindow: Duration(days: 14)),
+  fun('Fun', fixedWindow: Duration(days: 3), pictureLed: true);
 
-  const SourceKind(this.label);
+  const SourceKind(
+    this.label, {
+    this.feedsBriefing = false,
+    this.fixedWindow,
+    this.pictureLed = false,
+  });
 
   final String label;
+
+  /// Only News sources feed the Briefing.
+  final bool feedsBriefing;
+
+  /// How far back articles reach; null where the user sets it (News).
+  final Duration? fixedWindow;
+
+  /// Comics and memes are the picture: the reader shows it whole in the body
+  /// rather than as a cropped banner.
+  final bool pictureLed;
 }
 
 /// A Source of any [kind]; see GLOSSARY.md.

lib/services/feed_service.dart

@@ -23,15 +23,15 @@ class FeedService {
 
   static const _timeout = Duration(seconds: 20);
 
-  /// Fetches all [sources] in parallel and drops articles older than the age
-  /// [maxAgeOf] gives for their Source. Failing feeds are reported in
+  /// Fetches all [sources] in parallel and drops articles older than the time
+  /// window [windowOf] 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<Source> sources, {
-    required Duration Function(Source source) maxAgeOf,
+    required Duration Function(Source source) windowOf,
     String corsProxy = '',
   }) async {
     final errors = <String, String>{};
@@ -50,7 +50,7 @@ class FeedService {
       for (final (i, list) in results.indexed)
         for (final a in list)
           if ((a.published == null ||
-                  a.published!.isAfter(now.subtract(maxAgeOf(sources[i])))) &&
+                  a.published!.isAfter(now.subtract(windowOf(sources[i])))) &&
               seen.add(a.id))
             a,
     ];

lib/state/app_state.dart

@@ -82,22 +82,27 @@ class AppState extends ChangeNotifier {
       (settings.hidePaid && paywall.isPaid(a)) ||
       (settings.hideSponsored && paywall.isSponsored(a));
 
+  /// Articles from Sources whose kind passes [test] that the paid/sponsored
+  /// filters show, or with [hidden], those they hide.
+  Iterable<Article> _articlesWhere(bool Function(SourceKind kind) test,
+          {bool hidden = false}) =>
+      articles.where((a) => test(a.source.kind) && _isHidden(a) == hidden);
+
   /// 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();
+  /// uses News, the Learn tab the other kinds.
+  List<Article> articlesOf(SourceKind kind) => _articlesWhere((k) => k == kind).toList();
 
   /// 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;
+  int hiddenCountOf(SourceKind kind) => _articlesWhere((k) => k == kind, hidden: true).length;
+
+  /// What the Briefing is made from: the shown articles of the kinds that
+  /// feed it (News).
+  List<Article> get briefingArticles => _articlesWhere((k) => k.feedsBriefing).toList();
 
   /// 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),
-      };
+  Duration windowOf(SourceKind kind) =>
+      kind.fixedWindow ?? Duration(hours: settings.maxAgeHours);
 
   List<Source> get allSources => [..._curated, ...customSources];
 
@@ -119,7 +124,7 @@ class AppState extends ChangeNotifier {
     notifyListeners();
     final result = await _feeds.fetchAll(
       enabledSources,
-      maxAgeOf: (source) => windowOf(source.kind),
+      windowOf: (source) => windowOf(source.kind),
       corsProxy: settings.corsProxy,
     );
     articles = result.articles;
@@ -292,7 +297,7 @@ class AppState extends ChangeNotifier {
   Future<void> generateBriefing() async {
     final summarizer = _summarizer;
     if (summarizer == null || briefingLoading) return;
-    final articles = articlesOf(SourceKind.news);
+    final articles = briefingArticles;
     if (articles.isEmpty) {
       briefingError = 'No articles loaded yet. Pull to refresh the feed first.';
       notifyListeners();

lib/ui/article_screen.dart

@@ -6,7 +6,6 @@ import 'package:flutter/material.dart';
 import 'package:flutter_inappwebview/flutter_inappwebview.dart';
 
 import '../models/article.dart';
-import '../models/source.dart';
 import '../services/article_extractor.dart';
 import '../services/consent_service.dart';
 import '../services/content_blocking.dart';
@@ -276,9 +275,7 @@ class _ReaderView extends StatelessWidget {
         builder: (context, snapshot) {
           final loaded = snapshot.data;
           var blocks = loaded?.blocks ?? const <ReaderBlock>[];
-          // Comics and memes are the picture: show it whole in the body
-          // rather than as a cropped banner.
-          final pictureLed = article.source.kind == SourceKind.fun;
+          final pictureLed = article.source.kind.pictureLed;
           final banner = pictureLed ? null : article.imageUrl;
           // The page's own hero image duplicates the feed image shown on top.
           if (banner != null) {

lib/ui/briefing_screen.dart

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