diff --git a/lib/sync/notes_markdown.dart b/lib/sync/notes_markdown.dart
index ea62365..a611e75 100644
--- a/lib/sync/notes_markdown.dart
+++ b/lib/sync/notes_markdown.dart
@@ -11,7 +11,8 @@ import '../data/note.dart';
 /// rather than creating duplicates — the basis for "never lose ideas"
 /// recovery and round-tripping a backup.
 class NotesMarkdown {
-  const NotesMarkdown._();
+  // Private ctor: this is a static-only utility class, never instantiated.
+  const NotesMarkdown._(); // coverage:ignore-line
 
   static const _uuid = Uuid();
 
diff --git a/lib/ui/capture_screen.dart b/lib/ui/capture_screen.dart
index 17fb841..bbbdb93 100644
--- a/lib/ui/capture_screen.dart
+++ b/lib/ui/capture_screen.dart
@@ -1,4 +1,5 @@
 import 'package:flutter/material.dart';
+import 'package:http/http.dart' as http;
 import 'package:uuid/uuid.dart';
 
 import '../data/note.dart';
@@ -17,10 +18,15 @@ import 'settings_screen.dart';
 /// action finalises the current idea and clears the field for the next
 /// one (remote sync will hook in here later).
 class CaptureScreen extends StatefulWidget {
-  const CaptureScreen({required this.repository, super.key});
+  const CaptureScreen({required this.repository, this.httpClient, super.key});
 
   final NoteRepository repository;
 
+  /// Injectable HTTP client for the sync path. Production leaves this null
+  /// (the GitHubClient creates its own); tests pass a mock so the configured
+  /// sync flow can be exercised without real network access.
+  final http.Client? httpClient;
+
   @override
   State<CaptureScreen> createState() => _CaptureScreenState();
 }
@@ -108,8 +114,11 @@ class _CaptureScreenState extends State<CaptureScreen> {
     if (!mounted) return;
     final result = await Navigator.of(context).push<SyncSettings>(
       MaterialPageRoute(
-        builder: (_) =>
-            SettingsScreen(initial: current, repository: widget.repository),
+        builder: (_) => SettingsScreen(
+          initial: current,
+          repository: widget.repository,
+          httpClient: widget.httpClient,
+        ),
       ),
     );
     if (result != null && mounted) setState(() => _settings = result);
@@ -136,6 +145,7 @@ class _CaptureScreenState extends State<CaptureScreen> {
       owner: settings.owner,
       repo: settings.repo,
       token: settings.token,
+      httpClient: widget.httpClient,
     );
     try {
       final result = await _syncService.sync(widget.repository, client);
diff --git a/test/capture_screen_test.dart b/test/capture_screen_test.dart
index c1eb12d..2c50fae 100644
--- a/test/capture_screen_test.dart
+++ b/test/capture_screen_test.dart
@@ -1,8 +1,11 @@
 import 'package:flutter/material.dart';
 import 'package:flutter_test/flutter_test.dart';
+import 'package:http/http.dart' as http;
+import 'package:http/testing.dart';
 import 'package:shared_preferences/shared_preferences.dart';
 import 'package:todo/data/note.dart';
 import 'package:todo/ui/capture_screen.dart';
+import 'package:todo/ui/settings_screen.dart';
 
 import 'fake_note_repository.dart';
 
@@ -11,15 +14,36 @@ void main() {
   // widget tester's fake clock, so these tests inject a timer-free fake.
   // (NOTE: avoid pumpAndSettle — the autofocused field's cursor blink never
   // settles; pump explicit frames instead.)
-  Future<FakeNoteRepository> pumpCapture(WidgetTester tester) async {
-    SharedPreferences.setMockInitialValues({});
+  Future<FakeNoteRepository> pumpCapture(
+    WidgetTester tester, {
+    Map<String, Object> prefs = const {},
+    http.Client? httpClient,
+  }) async {
+    SharedPreferences.setMockInitialValues(prefs);
+    // Tall surface so a pushed settings screen builds its whole ListView.
+    tester.view.physicalSize = const Size(1200, 2800);
+    tester.view.devicePixelRatio = 1.0;
+    addTearDown(tester.view.resetPhysicalSize);
+    addTearDown(tester.view.resetDevicePixelRatio);
+
     final repo = FakeNoteRepository();
     addTearDown(repo.close);
-    await tester.pumpWidget(MaterialApp(home: CaptureScreen(repository: repo)));
+    await tester.pumpWidget(
+      MaterialApp(
+        home: CaptureScreen(repository: repo, httpClient: httpClient),
+      ),
+    );
     await tester.pump(); // flush initial stream + settings load
     return repo;
   }
 
+  // Seeds a fully configured GitHub sync so the configured `_sync` path runs.
+  const configuredPrefs = {
+    'sync.owner': 'o',
+    'sync.repo': 'r',
+    'sync.token': 'tok',
+  };
+
   testWidgets('pre-fills the structured template', (tester) async {
     await pumpCapture(tester);
 
@@ -135,4 +159,59 @@ void main() {
 
     expect((await repo.listNotes()).single.status, Status.inProgress);
   });
+
+  testWidgets('Sync with a configured token runs the sync service', (
+    tester,
+  ) async {
+    // Empty remote directory (404) → the service has nothing to merge and
+    // pushes this device's own changeset (PUT).
+    final mock = MockClient((req) async {
+      if (req.method == 'PUT') return http.Response('{}', 200);
+      return http.Response('', 404);
+    });
+    await pumpCapture(tester, prefs: configuredPrefs, httpClient: mock);
+
+    await tester.tap(find.byTooltip('Sync'));
+    await tester.pump(); // setState(_syncing = true)
+    await tester.pump(); // service runs, snackbar scheduled
+    await tester.pump(); // snackbar builds
+
+    expect(find.textContaining('Synced: merged 0 device'), findsOneWidget);
+  });
+
+  testWidgets('Sync surfaces a failure from the sync service', (tester) async {
+    final mock = MockClient((_) async => throw Exception('offline'));
+    await pumpCapture(tester, prefs: configuredPrefs, httpClient: mock);
+
+    await tester.tap(find.byTooltip('Sync'));
+    await tester.pump();
+    await tester.pump();
+    await tester.pump();
+
+    expect(find.textContaining('Sync failed'), findsOneWidget);
+  });
+
+  testWidgets('returning from settings adopts the saved configuration', (
+    tester,
+  ) async {
+    await pumpCapture(tester);
+
+    await tester.tap(find.byTooltip('Sync settings'));
+    await tester.pumpAndSettle(); // route transition
+    expect(find.text('Connect GitHub'), findsOneWidget); // settings is up
+
+    // Saving pops a SyncSettings back to the capture screen (covers the
+    // result-adoption branch in _openSettings). Scope to the settings route —
+    // the capture screen's own "Save" is still mounted behind it.
+    await tester.tap(
+      find.descendant(
+        of: find.byType(SettingsScreen),
+        matching: find.text('Save'),
+      ),
+    );
+    await tester.pumpAndSettle(); // save + pop transition
+
+    expect(find.text('Connect GitHub'), findsNothing); // back on capture
+    expect(find.byTooltip('Sync settings'), findsOneWidget);
+  });
 }
diff --git a/test/github_client_test.dart b/test/github_client_test.dart
index 9a641c8..3048228 100644
--- a/test/github_client_test.dart
+++ b/test/github_client_test.dart
@@ -95,4 +95,18 @@ void main() {
       throwsA(isA<GitHubApiException>()),
     );
   });
+
+  test('GitHubApiException.toString includes status and message', () {
+    expect(
+      GitHubApiException(500, 'boom').toString(),
+      'GitHubApiException(500): boom',
+    );
+  });
+
+  test('creates a default http client when none is injected', () {
+    // No httpClient → the constructor builds a real http.Client; just make
+    // sure that branch runs and the client closes cleanly (no request made).
+    final c = GitHubClient(owner: 'o', repo: 'r', token: 't');
+    addTearDown(c.close);
+  });
 }
diff --git a/test/github_device_auth_test.dart b/test/github_device_auth_test.dart
index ac5318d..88be7a4 100644
--- a/test/github_device_auth_test.dart
+++ b/test/github_device_auth_test.dart
@@ -152,4 +152,11 @@ void main() {
       ),
     );
   });
+
+  test('defaults to a real http client and delay when none are injected', () {
+    // Omitting httpClient/delay exercises the `?? http.Client()` and
+    // `?? Future.delayed` constructor fallbacks; no request is made.
+    final auth = GitHubDeviceAuth(clientId: 'c');
+    addTearDown(auth.close);
+  });
 }
diff --git a/test/note_repository_test.dart b/test/note_repository_test.dart
index ae61ce0..c9383d9 100644
--- a/test/note_repository_test.dart
+++ b/test/note_repository_test.dart
@@ -313,6 +313,44 @@ void main() {
     expect(notes.single.priority, Priority.medium);
   });
 
+  test('v1→v2 migration adds the status column with a default', () async {
+    final dir = await Directory.systemTemp.createTemp('todo_migration_v1');
+    final path = '${dir.path}/notes.db';
+    addTearDown(() => dir.delete(recursive: true));
+
+    // v1 schema predates the status column entirely.
+    final v1 = await SqliteCrdt.open(
+      path,
+      version: 1,
+      onCreate: (db, version) async {
+        await db.execute('''
+          CREATE TABLE notes (
+            id TEXT NOT NULL,
+            text TEXT NOT NULL DEFAULT '',
+            priority INTEGER NOT NULL DEFAULT 0,
+            created_at TEXT NOT NULL,
+            updated_at TEXT NOT NULL,
+            PRIMARY KEY (id)
+          )
+        ''');
+      },
+    );
+    final now = DateTime.now().toIso8601String();
+    await v1.execute(
+      'INSERT INTO notes (id, text, priority, created_at, updated_at) '
+      'VALUES (?1, ?2, ?3, ?4, ?5)',
+      ['old', 'pre-status idea', 1, now, now],
+    );
+    await v1.close();
+
+    // Reopening runs onUpgrade v1→v2 (adds status, default todo) then v2→v3.
+    final repo = await NoteRepository.open(path);
+    addTearDown(repo.close);
+    final notes = await repo.listNotes();
+    expect(notes.single.id, 'old');
+    expect(notes.single.status, Status.todo); // backfilled default
+  });
+
   group('sorting and streams', () {
     test('createdDesc and alphabetical orderings', () async {
       final repo = await NoteRepository.openInMemory();
@@ -371,4 +409,34 @@ void main() {
     final merged = await target.listNotes();
     expect(merged.single.text, 'shared idea');
   });
+
+  group('NoteFilter', () {
+    test('a default filter is empty (all facets cleared)', () {
+      // Evaluates the full conjunction in `isEmpty`, including the date bounds.
+      const filter = NoteFilter();
+      expect(filter.isEmpty, isTrue);
+      expect(filter.activeCount, 0);
+    });
+
+    test('a filter with any facet set is not empty', () {
+      expect(const NoteFilter(query: 'x').isEmpty, isFalse);
+      expect(const NoteFilter(statuses: {Status.done}).isEmpty, isFalse);
+    });
+
+    test('copyWith with no arguments preserves every facet', () {
+      final base = NoteFilter(
+        query: 'milk',
+        priorities: const {Priority.high},
+        statuses: const {Status.todo},
+        createdFrom: DateTime(2026, 1, 1),
+        updatedTo: DateTime(2026, 2, 2),
+      );
+      final clone = base.copyWith();
+      expect(clone.query, base.query);
+      expect(clone.priorities, base.priorities);
+      expect(clone.statuses, base.statuses);
+      expect(clone.createdFrom, base.createdFrom);
+      expect(clone.updatedTo, base.updatedTo);
+    });
+  });
 }
diff --git a/test/notes_list_screen_test.dart b/test/notes_list_screen_test.dart
index d90cf08..e93b2a4 100644
--- a/test/notes_list_screen_test.dart
+++ b/test/notes_list_screen_test.dart
@@ -250,4 +250,65 @@ void main() {
 
     expect(repo.lastFilter!.createdFrom, isNull);
   });
+
+  testWidgets('filter sheet toggles a priority and a Last-updated preset', (
+    tester,
+  ) async {
+    final repo = await pumpList(tester, seed: [note('a', 'x')]);
+
+    await tester.tap(find.byIcon(Icons.filter_list));
+    await tester.pump();
+    await tester.pump(const Duration(milliseconds: 300));
+
+    await tester.tap(find.text('High')); // priority chip toggle
+    // Second "Today" belongs to the Last-updated section.
+    await tester.tap(find.text('Today').last);
+    await tester.pump();
+    await tester.tap(find.text('Apply'));
+    await tester.pump();
+    await tester.pump(const Duration(milliseconds: 300));
+
+    expect(repo.lastFilter!.priorities, contains(Priority.high));
+    expect(repo.lastFilter!.updatedFrom, isNotNull);
+    expect(repo.lastFilter!.updatedTo, isNotNull);
+  });
+
+  testWidgets('a 30-day preset then Custom… confirms the seeded range', (
+    tester,
+  ) async {
+    final repo = await pumpList(tester, seed: [note('a', 'x')]);
+
+    await tester.tap(find.byIcon(Icons.filter_list));
+    await tester.pump();
+    await tester.pump(const Duration(milliseconds: 300));
+
+    await tester.tap(find.text('30 days').first); // _applyDays(30)
+    await tester.pump();
+    // Custom… opens the range picker seeded with the 30-day range
+    // (initialDateRange != null); confirming with Save returns that range.
+    await tester.tap(find.text('Custom…').first);
+    await tester.pump();
+    await tester.pump(const Duration(milliseconds: 300)); // picker opens
+    await tester.tap(find.text('Save'));
+    await tester.pump();
+    await tester.pump(const Duration(milliseconds: 300));
+    await tester.tap(find.text('Apply'));
+    await tester.pump();
+    await tester.pump(const Duration(milliseconds: 300));
+
+    expect(repo.lastFilter!.createdFrom, isNotNull);
+    expect(repo.lastFilter!.createdTo, isNotNull);
+  });
+
+  testWidgets('per-note sheet changes priority via a chip', (tester) async {
+    final repo = await pumpList(tester, seed: [note('a', 'Repriortise me')]);
+
+    await tester.tap(find.text('Repriortise me'));
+    await tester.pump();
+    await tester.pump(const Duration(milliseconds: 300));
+    await tester.tap(find.text('Low')); // default is Medium → change to Low
+    await tester.pump();
+
+    expect((await repo.listNotes()).single.priority, Priority.low);
+  });
 }
diff --git a/test/settings_screen_test.dart b/test/settings_screen_test.dart
index 838f22e..868c162 100644
--- a/test/settings_screen_test.dart
+++ b/test/settings_screen_test.dart
@@ -9,6 +9,7 @@ import 'package:http/testing.dart';
 import 'package:plugin_platform_interface/plugin_platform_interface.dart';
 import 'package:shared_preferences/shared_preferences.dart';
 import 'package:todo/data/note.dart';
+import 'package:todo/data/note_repository.dart';
 import 'package:todo/sync/notes_markdown.dart';
 import 'package:todo/sync/sync_settings.dart';
 import 'package:todo/ui/settings_screen.dart';
@@ -32,6 +33,26 @@ class _FakeFileSelector extends FileSelectorPlatform
   }) async => file;
 }
 
+/// Repository whose reads fail, to exercise the export error path.
+class _ExplodingRepo extends FakeNoteRepository {
+  @override
+  Future<List<Note>> listNotes({
+    NoteSort sort = NoteSort.modifiedDesc,
+    NoteFilter filter = const NoteFilter(),
+  }) async => throw Exception('db down');
+}
+
+/// File picker stub that throws, to exercise the import error path.
+class _ThrowingFileSelector extends FileSelectorPlatform
+    with MockPlatformInterfaceMixin {
+  @override
+  Future<XFile?> openFile({
+    List<XTypeGroup>? acceptedTypeGroups,
+    String? initialDirectory,
+    String? confirmButtonText,
+  }) async => throw Exception('picker blew up');
+}
+
 /// Stub launcher that records the URL instead of opening it, so `_openPage`
 /// can be exercised without a real platform channel.
 class _FakeUrlLauncher extends UrlLauncherPlatform
@@ -61,6 +82,7 @@ void main() {
     ),
     http.Client? httpClient,
     List<Note> seed = const [],
+    FakeNoteRepository? repository,
   }) async {
     SharedPreferences.setMockInitialValues({});
     // Tall surface so the whole settings ListView builds (its Backup section
@@ -70,7 +92,7 @@ void main() {
     addTearDown(tester.view.resetPhysicalSize);
     addTearDown(tester.view.resetDevicePixelRatio);
 
-    final repo = FakeNoteRepository(seed);
+    final repo = repository ?? FakeNoteRepository(seed);
     addTearDown(repo.close);
     await tester.pumpWidget(
       MaterialApp(
@@ -223,6 +245,20 @@ void main() {
     expect(find.textContaining('Exported'), findsOneWidget);
   });
 
+  testWidgets('Export surfaces a failure when the repository read fails', (
+    tester,
+  ) async {
+    await pumpSettings(tester, repository: _ExplodingRepo());
+
+    await tester.runAsync(() async {
+      await tester.tap(find.text('Export notes'));
+      await Future<void>.delayed(const Duration(milliseconds: 50));
+    });
+    await tester.pump();
+
+    expect(find.textContaining('Export failed'), findsOneWidget);
+  });
+
   testWidgets('Save persists the settings and closes the screen', (
     tester,
   ) async {
@@ -319,6 +355,18 @@ void main() {
     expect(await repo.listNotes(), isEmpty);
   });
 
+  testWidgets('Import surfaces a failure from the picker', (tester) async {
+    FileSelectorPlatform.instance = _ThrowingFileSelector();
+    final repo = await pumpSettings(tester);
+
+    await tester.tap(find.text('Import notes'));
+    await tester.pump();
+    await tester.pump();
+
+    expect(find.textContaining('Import failed'), findsOneWidget);
+    expect(await repo.listNotes(), isEmpty);
+  });
+
   testWidgets('device dialog: failed poll shows the error and Open launches', (
     tester,
   ) async {
diff --git a/test/sync_settings_test.dart b/test/sync_settings_test.dart
index cbef6b3..20c7566 100644
--- a/test/sync_settings_test.dart
+++ b/test/sync_settings_test.dart
@@ -65,5 +65,12 @@ void main() {
     expect(next.repo, 'r');
     expect(next.token, 'new');
     expect(next.clientId, 'c');
+
+    // No-arg copy exercises the `?? this.x` fallback on every field.
+    final clone = base.copyWith();
+    expect(clone.owner, 'o');
+    expect(clone.repo, 'r');
+    expect(clone.token, 't');
+    expect(clone.clientId, 'c');
   });
 }