improved tab & topic handling

app/lib/features/topics/domain/providers.dart

@@ -1,19 +1,14 @@
 import 'dart:ui';
 
 import 'package:collection/collection.dart';
-import 'package:lensai/features/topics/data/database/database.dart';
+import 'package:lensai/features/topics/data/models/topic_data.dart';
+import 'package:lensai/features/topics/data/providers.dart';
 import 'package:lensai/features/topics/domain/repositories/topic.dart';
 import 'package:lensai/features/topics/utils/color_palette.dart';
 import 'package:riverpod_annotation/riverpod_annotation.dart';
 
 part 'providers.g.dart';
 
-@Riverpod()
-Stream<List<TopicData>> topicList(TopicListRef ref) {
-  final repository = ref.watch(topicRepositoryProvider.notifier);
-  return repository.watchTopics();
-}
-
 @Riverpod(keepAlive: true)
 class SelectedTopic extends _$SelectedTopic {
   void setTopic(String id) {
@@ -40,21 +35,22 @@ class SelectedTopic extends _$SelectedTopic {
 
 @Riverpod()
 Stream<TopicData?> selectedTopicData(SelectedTopicDataRef ref) {
-  final repository = ref.watch(topicRepositoryProvider.notifier);
-  final selectedBangTrigger = ref.watch(selectedTopicProvider);
-  return repository.watchTopic(selectedBangTrigger);
-}
+  final db = ref.watch(tabDatabaseProvider);
+  final selectedTopic = ref.watch(selectedTopicProvider);
 
-@Riverpod()
-Future<Set<Color>> distinctTopicColors(DistinctTopicColorsRef ref) {
-  final repository = ref.watch(topicRepositoryProvider.notifier);
-  return repository.getDistinctColors();
+  if (selectedTopic != null) {
+    return db.topicDao.getTopicData(selectedTopic).watchSingleOrNull();
+  }
+
+  return Stream.value(null);
 }
 
 @Riverpod()
 Future<Color> unusedRandomTopicColor(UnusedRandomTopicColorRef ref) async {
+  final repository = ref.watch(topicRepositoryProvider.notifier);
+
   final allColors = colorTypes.flattened.toList();
-  final usedColors = await ref.read(distinctTopicColorsProvider.future);
+  final usedColors = await repository.getDistinctColors();
 
   Color randomColor;
   do {