Add viewed history, diagnostics, tag chips and SWF viewer

lib/backend/repositories/viewed_post_repository.dart

@@ -0,0 +1,59 @@
+import 'package:isar/isar.dart';
+
+import '../../core/database/app_database.dart';
+import '../../core/database/database_service.dart';
+import '../../core/utils/result.dart';
+import '../models/viewed_post.dart';
+
+class ViewedPostRepository {
+  ViewedPostRepository(this._databaseService);
+
+  final DatabaseService _databaseService;
+
+  Future<Result<void>> markViewed(String providerId, String postId) {
+    return _databaseService.safeWrite((isar) async {
+      final key = ViewedPost.keyFor(providerId, postId);
+      await isar.viewedPostEntitys.put(
+        ViewedPostEntity.fromModel(
+          ViewedPost(
+            viewedKey: key,
+            providerId: providerId,
+            postId: postId,
+            viewedAt: DateTime.now(),
+          ),
+        ),
+      );
+    });
+  }
+
+  Future<Result<bool>> exists(String providerId, String postId) {
+    return _databaseService.safeRead((isar) async {
+      final entity = await isar.viewedPostEntitys
+          .filter()
+          .viewedKeyEqualTo(ViewedPost.keyFor(providerId, postId))
+          .findFirst();
+      return entity != null;
+    });
+  }
+
+  Future<Result<Set<String>>> keys() {
+    return _databaseService.safeRead((isar) async {
+      final items = await isar.viewedPostEntitys.where().findAll();
+      return items.map((item) => item.viewedKey).toSet();
+    });
+  }
+
+  Future<Result<List<ViewedPost>>> recent() {
+    return _databaseService.safeRead((isar) async {
+      final items = await isar.viewedPostEntitys.where().findAll();
+      items.sort((a, b) => b.viewedAt.compareTo(a.viewedAt));
+      return items.map((item) => item.toModel()).toList();
+    });
+  }
+
+  Future<Result<void>> clear() {
+    return _databaseService.safeWrite((isar) async {
+      await isar.viewedPostEntitys.clear();
+    });
+  }
+}