feat: store subscription posts with a read mark and split the library controller

app/lib/application/controllers/bookmarks_controller.dart

@@ -0,0 +1,35 @@
+import 'package:signals/signals.dart';
+
+import '../../database/database.dart';
+
+/// Which pages the reader has bookmarked. Only the set of addresses is held
+/// here, because that is all the chrome watches; the list itself is read from
+/// the database whenever a page needs it.
+class BookmarksController {
+  BookmarksController(this._db);
+
+  final MewsDatabase _db;
+
+  final bookmarkedUrls = signal(<String>{});
+
+  Future<void> load() async {
+    final rows = await _db.allBookmarks();
+    bookmarkedUrls.value = rows.map((row) => row.url).toSet();
+  }
+
+  bool isBookmarked(String url) => bookmarkedUrls.value.contains(url);
+
+  Future<void> toggle(String url, String? title) async {
+    if (isBookmarked(url)) {
+      await remove(url);
+      return;
+    }
+    await _db.addBookmark(url, title);
+    bookmarkedUrls.value = {...bookmarkedUrls.value, url};
+  }
+
+  Future<void> remove(String url) async {
+    await _db.removeBookmark(url);
+    bookmarkedUrls.value = {...bookmarkedUrls.value}..remove(url);
+  }
+}