Fix deferred folder changes and recovery after failed library clears

app/lib/folders/watched_folders.dart

@@ -812,8 +812,13 @@ class WatchedFolders extends ChangeNotifier with WidgetsBindingObserver {
 
     final needsObservation = file.modified == 0 || file.modified > now;
 
-    if (needsObservation && (previous?['stamp'] != file.stamp || previous?['seen'] == null)) {
-      await repository.save('files', recordId, {...?previous, 'stamp': file.stamp, 'seen': now}, folderId: folder.id);
+    if (needsObservation && (previous?['observedStamp'] != file.stamp || previous?['seen'] == null)) {
+      await repository.save('files', recordId, {
+        ...?previous,
+        'observedStamp': file.stamp,
+        'seen': now,
+      }, folderId: folder.id);
+
       return _FileResult.deferred;
     }
 

app/lib/widgets/profile/storage_sync_settings_section.dart

@@ -537,18 +537,20 @@ class StorageSyncSettingsSection extends StatelessWidget {
       final database = context.read<PapyrusPowerSyncService>();
       await folders?.suspend();
 
-      await database.clearGuestLibrary(
-        deleteFiles: (books) async {
-          for (final book in books) {
-            await files.deleteBookFile(book.id);
-          }
-
-          await files.clearCoverFiles(MediaStorageScope.localGuest);
-          await folders?.clear();
-        },
-      );
-
-      folders?.resume();
+      try {
+        await database.clearGuestLibrary(
+          deleteFiles: (books) async {
+            for (final book in books) {
+              await files.deleteBookFile(book.id);
+            }
+
+            await files.clearCoverFiles(MediaStorageScope.localGuest);
+            await folders?.clear();
+          },
+        );
+      } finally {
+        folders?.resume();
+      }
 
       messenger.showSnackBar(
         snackBarAnimationStyle: snackBarAnimationStyle,

app/test/folders/watched_folders_test.dart

@@ -455,6 +455,28 @@ void main() {
     expect(target.books, hasLength(1));
   });
 
+  for (final clockCatchesUp in [false, true]) {
+    test('future-dated changes stay eligible when the clock catches up: $clockCatchesUp', () async {
+      access.put('book.epub', [1]);
+      final folder = await connect();
+      final original = target.books.single;
+      access.put('book.epub', [2]);
+      access.reportedModified = DateTime.now().add(const Duration(seconds: 10)).millisecondsSinceEpoch;
+      await folders.scanNow(folder.id);
+      expect(await folders.issues(folder.id), isEmpty);
+      expect(access.reads, 1);
+
+      if (clockCatchesUp) {
+        clockOffset = const Duration(seconds: 20);
+      }
+
+      await folders.scanNow(folder.id);
+      expect((await folders.issues(folder.id)).single['state'], 'changed');
+      expect(target.books.single, same(original));
+      expect(access.reads, 2);
+    });
+  }
+
   for (final condition in ['recent', 'missing timestamp', 'future timestamp', 'changed during read']) {
     test('one-time selections finish files deferred for $condition before pausing', () async {
       await folders.activate(null);

app/test/pages/profile_storage_sync_test.dart

@@ -11,6 +11,7 @@ import 'package:papyrus/auth/papyrus_api_config.dart';
 import 'package:papyrus/auth/token_store.dart';
 import 'package:papyrus/data/data_store.dart';
 import 'package:papyrus/data/repositories/book_repository.dart';
+import 'package:papyrus/folders/watched_folders.dart';
 import 'package:papyrus/media/media_upload_queue.dart';
 import 'package:papyrus/media/media_storage_scope.dart';
 import 'package:papyrus/services/book_import_service_stub.dart'
@@ -129,6 +130,29 @@ class _Files extends BookImportService {
   }
 }
 
+class _Folders extends ChangeNotifier implements WatchedFolders {
+  bool suspended = false;
+  int clearCalls = 0;
+
+  @override
+  Future<void> suspend() async {
+    suspended = true;
+  }
+
+  @override
+  void resume() {
+    suspended = false;
+  }
+
+  @override
+  Future<void> clear() async {
+    clearCalls++;
+  }
+
+  @override
+  dynamic noSuchMethod(Invocation invocation) => super.noSuchMethod(invocation);
+}
+
 void main() {
   setUp(() {
     SharedPreferences.setMockInitialValues({});
@@ -162,6 +186,7 @@ void main() {
     AcquisitionAvailabilityProvider? acquisitionAvailabilityProvider,
     Widget Function(Widget page)? pageBuilder,
     BookImportService? files,
+    WatchedFolders? folders,
   }) async {
     final prefs = await SharedPreferences.getInstance();
 
@@ -179,6 +204,7 @@ void main() {
         ),
         Provider<PapyrusPowerSyncService>.value(value: powerSyncService),
         if (files != null) Provider<BookImportService>.value(value: files),
+        if (folders != null) ChangeNotifierProvider<WatchedFolders>.value(value: folders),
         StreamProvider<SyncState>.value(value: powerSyncService.syncStates, initialData: powerSyncService.syncState),
         ChangeNotifierProvider<AuthProvider>.value(value: authProvider),
         ChangeNotifierProvider<AcquisitionAvailabilityProvider>.value(
@@ -210,13 +236,16 @@ void main() {
     final auth = await buildAuthProvider(guest: true);
     final service = _FakePowerSyncService(currentMode: LibraryDatabaseMode.guest, currentSyncState: const SyncState());
     final files = _Files()..failDeletion = true;
+    final folders = _Folders();
+    addTearDown(folders.dispose);
     service.guestBooks = [Book(id: 'guest-book', title: 'Guest book', author: 'Reader', addedAt: DateTime.now())];
 
     await tester.pumpWidget(
       await buildPage(
         authProvider: auth,
         powerSyncService: service,
         files: files,
+        folders: folders,
         pageBuilder: (_) => const Scaffold(body: StorageSyncSettingsSection()),
       ),
     );
@@ -229,6 +258,8 @@ void main() {
     expect(find.textContaining('Could not clear local library'), findsOneWidget);
     expect(service.guestBooks.single.id, 'guest-book');
     expect(service.clearGuestLibraryCalls, 0);
+    expect(folders.suspended, isFalse);
+    expect(folders.clearCalls, 0);
     files.failDeletion = false;
     await tester.tap(find.text('Clear local library'));
     await tester.pumpAndSettle();
@@ -238,6 +269,8 @@ void main() {
     expect(files.clearedScopes, [MediaStorageScope.localGuest]);
     expect(service.guestBooks, isEmpty);
     expect(service.clearGuestLibraryCalls, 1);
+    expect(folders.suspended, isFalse);
+    expect(folders.clearCalls, 1);
     expect(auth.isOfflineMode, isTrue);
   });