feat(D2): add task check-coverage and enforce gate in check-fast

Adds a standalone `task check-coverage` that runs unit+widget tests and
then fails if coverage drops below the 80% gate. Wires it into
`check-fast` so every pre-commit run also blocks regressions.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Taskfile.yml

@@ -331,6 +331,12 @@ tasks:
     cmds:
       - fvm dart run scripts/check_coverage.dart
 
+  check-coverage:
+    desc: Run unit+widget tests with coverage, then fail if the gate is not met
+    deps: [test]
+    cmds:
+      - task: coverage
+
   website-dev:
     desc: Run Hugo development server
     cmds:
@@ -361,8 +367,8 @@ tasks:
           ${SSH_USER}@${SSH_HOST}:public_html/
 
   check-fast:
-    desc: Pre-commit checks — analyze + unit tests + widget tests (no build, no integration)
-    deps: [analyze, test, check-hygiene]
+    desc: Pre-commit checks — analyze + unit+widget tests + coverage gate (no build, no integration)
+    deps: [analyze, check-coverage, check-hygiene]
 
   check-hygiene:
     desc: Verify that no forbidden files (like home dir config) are tracked

lib/ui/screens/email_list_screen.dart

@@ -10,6 +10,7 @@ import 'package:sharedinbox/core/models/email.dart';
 import 'package:sharedinbox/core/models/undo_action.dart';
 import 'package:sharedinbox/core/repositories/email_repository.dart';
 import 'package:sharedinbox/di.dart';
+import 'package:sharedinbox/ui/widgets/email_tile.dart';
 import 'package:sharedinbox/ui/widgets/folder_drawer.dart';
 import 'package:sharedinbox/ui/widgets/snooze_picker.dart';
 
@@ -711,10 +712,9 @@ class _EmailListScreenState extends ConsumerState<EmailListScreen> {
       itemBuilder: (ctx, i) {
         final e = emails[i];
         final isSelected = _selectedSearchIds.contains(e.id);
-        final sender = e.from.isNotEmpty
-            ? (e.from.first.name ?? e.from.first.email)
-            : '(unknown)';
-        return ListTile(
+        return EmailTile(
+          email: e,
+          selected: isSelected,
           leading: SizedBox(
             width: 40,
             child: _selecting
@@ -722,25 +722,7 @@ class _EmailListScreenState extends ConsumerState<EmailListScreen> {
                     value: isSelected,
                     onChanged: (_) => _toggleSearchSelection(e.id),
                   )
-                : Icon(
-                    e.isSeen ? Icons.mail_outline : Icons.mail,
-                    color: e.isSeen ? null : Theme.of(ctx).colorScheme.primary,
-                  ),
-          ),
-          title: Text(
-            sender,
-            style:
-                e.isSeen ? null : const TextStyle(fontWeight: FontWeight.bold),
-          ),
-          subtitle: Text(
-            e.subject ?? '(no subject)',
-            maxLines: 1,
-            overflow: TextOverflow.ellipsis,
-          ),
-          selected: isSelected,
-          trailing: Text(
-            e.sentAt != null ? _dateFmt.format(e.sentAt!) : '',
-            style: Theme.of(ctx).textTheme.bodySmall,
+                : null,
           ),
           onTap: _selecting
               ? () => _toggleSearchSelection(e.id)

lib/ui/screens/search_screen.dart

@@ -8,6 +8,7 @@ import 'package:sharedinbox/core/models/email.dart';
 import 'package:sharedinbox/core/models/mailbox.dart';
 import 'package:sharedinbox/core/utils/logger.dart';
 import 'package:sharedinbox/di.dart';
+import 'package:sharedinbox/ui/widgets/email_tile.dart';
 
 class SearchScreen extends ConsumerStatefulWidget {
   const SearchScreen({super.key, this.accountId});
@@ -155,7 +156,15 @@ class _SearchScreenState extends ConsumerState<SearchScreen> {
         if (r.emails.isNotEmpty) ...[
           const _SectionHeader('Messages'),
           for (final e in r.emails)
-            _EmailTile(email: e, accountId: e.accountId),
+            EmailTile(
+              email: e,
+              showLocation: true,
+              onTap: () => context.push(
+                '/accounts/${e.accountId}/mailboxes'
+                '/${Uri.encodeComponent(e.mailboxPath)}'
+                '/emails/${Uri.encodeComponent(e.id)}',
+              ),
+            ),
         ],
       ],
     );
@@ -246,42 +255,3 @@ class _AddressTile extends StatelessWidget {
     );
   }
 }
-
-class _EmailTile extends StatelessWidget {
-  const _EmailTile({required this.email, required this.accountId});
-  final Email email;
-  final String accountId;
-
-  @override
-  Widget build(BuildContext context) {
-    final sender = email.from.isNotEmpty
-        ? (email.from.first.name ?? email.from.first.email)
-        : '(unknown)';
-    return ListTile(
-      leading: Icon(
-        email.isSeen ? Icons.mail_outline : Icons.mail,
-        color: email.isSeen ? null : Theme.of(context).colorScheme.primary,
-      ),
-      title: Text(sender),
-      subtitle: Column(
-        crossAxisAlignment: CrossAxisAlignment.start,
-        children: [
-          Text(
-            email.subject ?? '(no subject)',
-            maxLines: 1,
-            overflow: TextOverflow.ellipsis,
-          ),
-          Text(
-            '$accountId • ${email.mailboxPath}',
-            style: Theme.of(context).textTheme.bodySmall,
-          ),
-        ],
-      ),
-      onTap: () => context.push(
-        '/accounts/$accountId/mailboxes'
-        '/${Uri.encodeComponent(email.mailboxPath)}'
-        '/emails/${Uri.encodeComponent(email.id)}',
-      ),
-    );
-  }
-}

lib/ui/widgets/email_tile.dart

@@ -0,0 +1,74 @@
+import 'package:flutter/material.dart';
+import 'package:intl/intl.dart';
+
+import 'package:sharedinbox/core/models/email.dart';
+
+final _dateFmt = DateFormat('MMM d');
+
+/// A flat list tile for an individual [email].
+///
+/// Used in search-result lists and the per-mailbox search overlay.
+/// Pass a custom [leading] widget to support selection-mode checkboxes.
+class EmailTile extends StatelessWidget {
+  const EmailTile({
+    super.key,
+    required this.email,
+    required this.onTap,
+    this.leading,
+    this.selected = false,
+    this.onLongPress,
+    this.showLocation = false,
+  });
+
+  final Email email;
+  final VoidCallback onTap;
+  final Widget? leading;
+  final bool selected;
+  final VoidCallback? onLongPress;
+
+  /// When true, appends `accountId • mailboxPath` as a second subtitle line.
+  final bool showLocation;
+
+  @override
+  Widget build(BuildContext context) {
+    final sender = email.from.isNotEmpty
+        ? (email.from.first.name ?? email.from.first.email)
+        : '(unknown)';
+    final date = email.sentAt != null ? _dateFmt.format(email.sentAt!) : '';
+
+    return ListTile(
+      leading: leading ??
+          Icon(
+            email.isSeen ? Icons.mail_outline : Icons.mail,
+            color: email.isSeen ? null : Theme.of(context).colorScheme.primary,
+          ),
+      title: Text(
+        sender,
+        style:
+            email.isSeen ? null : const TextStyle(fontWeight: FontWeight.bold),
+        overflow: TextOverflow.ellipsis,
+      ),
+      subtitle: Column(
+        crossAxisAlignment: CrossAxisAlignment.start,
+        children: [
+          Text(
+            email.subject ?? '(no subject)',
+            maxLines: 1,
+            overflow: TextOverflow.ellipsis,
+          ),
+          if (showLocation)
+            Text(
+              '${email.accountId} • ${email.mailboxPath}',
+              style: Theme.of(context).textTheme.bodySmall,
+            ),
+        ],
+      ),
+      trailing: date.isEmpty
+          ? null
+          : Text(date, style: Theme.of(context).textTheme.bodySmall),
+      selected: selected,
+      onTap: onTap,
+      onLongPress: onLongPress,
+    );
+  }
+}

test/widget/helpers.dart

@@ -30,6 +30,7 @@ import 'package:sharedinbox/ui/screens/email_detail_screen.dart';
 import 'package:sharedinbox/ui/screens/email_list_screen.dart';
 import 'package:sharedinbox/ui/screens/mailbox_list_screen.dart';
 import 'package:sharedinbox/ui/screens/search_screen.dart';
+import 'package:sharedinbox/ui/screens/thread_detail_screen.dart';
 
 // ---------------------------------------------------------------------------
 // Fake repositories
@@ -381,6 +382,18 @@ Widget buildApp({
                   ),
                 ],
               ),
+              GoRoute(
+                path: ':mailboxPath/threads/:threadId',
+                builder: (ctx, state) => ThreadDetailScreen(
+                  accountId: state.pathParameters['accountId']!,
+                  mailboxPath: Uri.decodeComponent(
+                    state.pathParameters['mailboxPath']!,
+                  ),
+                  threadId: Uri.decodeComponent(
+                    state.pathParameters['threadId']!,
+                  ),
+                ),
+              ),
             ],
           ),
         ],

test/widget/search_screen_test.dart

@@ -0,0 +1,182 @@
+import 'package:flutter/material.dart';
+import 'package:flutter_test/flutter_test.dart';
+
+import 'package:sharedinbox/core/models/mailbox.dart';
+import 'package:sharedinbox/di.dart';
+
+import 'helpers.dart';
+
+void main() {
+  group('SearchScreen', () {
+    testWidgets('shows placeholder hint text when empty', (tester) async {
+      await tester.pumpWidget(
+        buildApp(
+          initialLocation: '/accounts/acc-1/search',
+          overrides: [
+            accountRepositoryProvider.overrideWithValue(
+              FakeAccountRepository([kTestAccount]),
+            ),
+            mailboxRepositoryProvider.overrideWithValue(
+              FakeMailboxRepository(),
+            ),
+            emailRepositoryProvider.overrideWithValue(FakeEmailRepository()),
+          ],
+        ),
+      );
+      await tester.pumpAndSettle();
+
+      expect(find.text('Type 3+ characters to search'), findsOneWidget);
+    });
+
+    testWidgets('typing fewer than 3 characters does not trigger search', (
+      tester,
+    ) async {
+      await tester.pumpWidget(
+        buildApp(
+          initialLocation: '/accounts/acc-1/search',
+          overrides: [
+            accountRepositoryProvider.overrideWithValue(
+              FakeAccountRepository([kTestAccount]),
+            ),
+            mailboxRepositoryProvider.overrideWithValue(
+              FakeMailboxRepository(),
+            ),
+            emailRepositoryProvider.overrideWithValue(FakeEmailRepository()),
+          ],
+        ),
+      );
+      await tester.pumpAndSettle();
+
+      await tester.enterText(find.byType(TextField), 'hi');
+      await tester.pump(const Duration(milliseconds: 400));
+
+      expect(find.text('Type 3+ characters to search'), findsOneWidget);
+      expect(find.text('No results'), findsNothing);
+    });
+
+    testWidgets('shows "No results" when search returns nothing', (
+      tester,
+    ) async {
+      await tester.pumpWidget(
+        buildApp(
+          initialLocation: '/accounts/acc-1/search',
+          overrides: [
+            accountRepositoryProvider.overrideWithValue(
+              FakeAccountRepository([kTestAccount]),
+            ),
+            mailboxRepositoryProvider.overrideWithValue(
+              FakeMailboxRepository(),
+            ),
+            emailRepositoryProvider.overrideWithValue(FakeEmailRepository()),
+          ],
+        ),
+      );
+      await tester.pumpAndSettle();
+
+      await tester.enterText(find.byType(TextField), 'xyz');
+      await tester.pump(const Duration(milliseconds: 400));
+      await tester.pumpAndSettle();
+
+      expect(find.text('No results'), findsOneWidget);
+    });
+
+    testWidgets('shows email results under "Messages" section', (
+      tester,
+    ) async {
+      final email = testEmail(subject: 'Invoice Q3');
+      await tester.pumpWidget(
+        buildApp(
+          initialLocation: '/accounts/acc-1/search',
+          overrides: [
+            accountRepositoryProvider.overrideWithValue(
+              FakeAccountRepository([kTestAccount]),
+            ),
+            mailboxRepositoryProvider.overrideWithValue(
+              FakeMailboxRepository(),
+            ),
+            emailRepositoryProvider.overrideWithValue(
+              FakeEmailRepository(searchResults: [email]),
+            ),
+          ],
+        ),
+      );
+      await tester.pumpAndSettle();
+
+      await tester.enterText(find.byType(TextField), 'inv');
+      await tester.pump(const Duration(milliseconds: 400));
+      await tester.pumpAndSettle();
+
+      expect(find.text('Messages'), findsOneWidget);
+      expect(find.text('Invoice Q3'), findsOneWidget);
+    });
+
+    testWidgets('shows folder results under "Folders" section', (
+      tester,
+    ) async {
+      const archiveMailbox = Mailbox(
+        id: 'acc-1:Archive',
+        accountId: 'acc-1',
+        path: 'Archive',
+        name: 'Archive',
+        unreadCount: 0,
+        totalCount: 5,
+      );
+      await tester.pumpWidget(
+        buildApp(
+          initialLocation: '/accounts/acc-1/search',
+          overrides: [
+            accountRepositoryProvider.overrideWithValue(
+              FakeAccountRepository([kTestAccount]),
+            ),
+            mailboxRepositoryProvider.overrideWithValue(
+              FakeMailboxRepository([archiveMailbox]),
+            ),
+            emailRepositoryProvider.overrideWithValue(FakeEmailRepository()),
+          ],
+        ),
+      );
+      await tester.pumpAndSettle();
+
+      await tester.enterText(find.byType(TextField), 'arc');
+      await tester.pump(const Duration(milliseconds: 400));
+      await tester.pumpAndSettle();
+
+      expect(find.text('Folders'), findsOneWidget);
+      expect(find.text('Archive'), findsOneWidget);
+    });
+
+    testWidgets('tapping clear button resets results to placeholder', (
+      tester,
+    ) async {
+      final email = testEmail(subject: 'Found email');
+      await tester.pumpWidget(
+        buildApp(
+          initialLocation: '/accounts/acc-1/search',
+          overrides: [
+            accountRepositoryProvider.overrideWithValue(
+              FakeAccountRepository([kTestAccount]),
+            ),
+            mailboxRepositoryProvider.overrideWithValue(
+              FakeMailboxRepository(),
+            ),
+            emailRepositoryProvider.overrideWithValue(
+              FakeEmailRepository(searchResults: [email]),
+            ),
+          ],
+        ),
+      );
+      await tester.pumpAndSettle();
+
+      await tester.enterText(find.byType(TextField), 'found');
+      await tester.pump(const Duration(milliseconds: 400));
+      await tester.pumpAndSettle();
+      expect(find.text('Found email'), findsOneWidget);
+
+      await tester.tap(find.byIcon(Icons.clear));
+      await tester.pumpAndSettle();
+
+      expect(find.text('Found email'), findsNothing);
+      expect(find.text('Type 3+ characters to search'), findsOneWidget);
+    });
+  });
+}

test/widget/thread_detail_screen_test.dart

@@ -0,0 +1,198 @@
+import 'package:flutter/material.dart';
+import 'package:flutter_test/flutter_test.dart';
+
+import 'package:sharedinbox/core/models/email.dart';
+import 'package:sharedinbox/di.dart';
+
+import 'helpers.dart';
+
+Email _threadEmail({
+  String id = 'acc-1:10',
+  bool isFlagged = false,
+  bool isSeen = true,
+}) =>
+    Email(
+      id: id,
+      accountId: 'acc-1',
+      mailboxPath: 'INBOX',
+      uid: 10,
+      threadId: 'thread-1',
+      subject: 'Project update',
+      receivedAt: DateTime(2024, 6),
+      sentAt: DateTime(2024, 6, 1, 9),
+      from: const [EmailAddress(name: 'Bob', email: 'bob@example.com')],
+      to: const [EmailAddress(email: 'alice@example.com')],
+      cc: const [],
+      isSeen: isSeen,
+      isFlagged: isFlagged,
+      hasAttachment: false,
+    );
+
+void main() {
+  group('ThreadDetailScreen', () {
+    testWidgets('shows "Thread not found or empty" when thread is empty', (
+      tester,
+    ) async {
+      await tester.pumpWidget(
+        buildApp(
+          initialLocation: '/accounts/acc-1/mailboxes/INBOX/threads/thread-1',
+          overrides: [
+            accountRepositoryProvider.overrideWithValue(
+              FakeAccountRepository([kTestAccount]),
+            ),
+            mailboxRepositoryProvider.overrideWithValue(
+              FakeMailboxRepository(),
+            ),
+            emailRepositoryProvider.overrideWithValue(FakeEmailRepository()),
+          ],
+        ),
+      );
+      await tester.pumpAndSettle();
+
+      expect(find.text('Thread not found or empty'), findsOneWidget);
+    });
+
+    testWidgets('shows sender name for email in thread', (tester) async {
+      final email = _threadEmail();
+      await tester.pumpWidget(
+        buildApp(
+          initialLocation: '/accounts/acc-1/mailboxes/INBOX/threads/thread-1',
+          overrides: [
+            accountRepositoryProvider.overrideWithValue(
+              FakeAccountRepository([kTestAccount]),
+            ),
+            mailboxRepositoryProvider.overrideWithValue(
+              FakeMailboxRepository(),
+            ),
+            emailRepositoryProvider.overrideWithValue(
+              FakeEmailRepository(emails: [email]),
+            ),
+          ],
+        ),
+      );
+      await tester.pumpAndSettle();
+
+      expect(find.textContaining('Bob'), findsOneWidget);
+    });
+
+    testWidgets('last email in thread is expanded by default', (tester) async {
+      final email = _threadEmail();
+      await tester.pumpWidget(
+        buildApp(
+          initialLocation: '/accounts/acc-1/mailboxes/INBOX/threads/thread-1',
+          overrides: [
+            accountRepositoryProvider.overrideWithValue(
+              FakeAccountRepository([kTestAccount]),
+            ),
+            mailboxRepositoryProvider.overrideWithValue(
+              FakeMailboxRepository(),
+            ),
+            emailRepositoryProvider.overrideWithValue(
+              FakeEmailRepository(
+                emails: [email],
+                emailBody: const EmailBody(
+                  emailId: 'acc-1:10',
+                  textBody: 'Hello body text',
+                  attachments: [],
+                ),
+              ),
+            ),
+          ],
+        ),
+      );
+      await tester.pumpAndSettle();
+
+      // Reply and delete buttons are visible for the expanded card.
+      expect(find.byIcon(Icons.reply), findsOneWidget);
+      expect(find.byIcon(Icons.delete_outline), findsOneWidget);
+    });
+
+    testWidgets('tapping an expanded card collapses it', (tester) async {
+      final email = _threadEmail();
+      await tester.pumpWidget(
+        buildApp(
+          initialLocation: '/accounts/acc-1/mailboxes/INBOX/threads/thread-1',
+          overrides: [
+            accountRepositoryProvider.overrideWithValue(
+              FakeAccountRepository([kTestAccount]),
+            ),
+            mailboxRepositoryProvider.overrideWithValue(
+              FakeMailboxRepository(),
+            ),
+            emailRepositoryProvider.overrideWithValue(
+              FakeEmailRepository(
+                emails: [email],
+                emailBody: const EmailBody(
+                  emailId: 'acc-1:10',
+                  textBody: 'Hello body text',
+                  attachments: [],
+                ),
+              ),
+            ),
+          ],
+        ),
+      );
+      await tester.pumpAndSettle();
+
+      // Tap the expand_less icon to collapse.
+      await tester.tap(find.byIcon(Icons.expand_less));
+      await tester.pumpAndSettle();
+
+      expect(find.byIcon(Icons.reply), findsNothing);
+      expect(find.byIcon(Icons.expand_more), findsOneWidget);
+    });
+
+    testWidgets('flagged email shows star icon', (tester) async {
+      final email = _threadEmail(isFlagged: true);
+      await tester.pumpWidget(
+        buildApp(
+          initialLocation: '/accounts/acc-1/mailboxes/INBOX/threads/thread-1',
+          overrides: [
+            accountRepositoryProvider.overrideWithValue(
+              FakeAccountRepository([kTestAccount]),
+            ),
+            mailboxRepositoryProvider.overrideWithValue(
+              FakeMailboxRepository(),
+            ),
+            emailRepositoryProvider.overrideWithValue(
+              FakeEmailRepository(emails: [email]),
+            ),
+          ],
+        ),
+      );
+      await tester.pumpAndSettle();
+
+      expect(find.byIcon(Icons.star), findsOneWidget);
+    });
+
+    testWidgets('expanded card shows plain text body', (tester) async {
+      final email = _threadEmail();
+      await tester.pumpWidget(
+        buildApp(
+          initialLocation: '/accounts/acc-1/mailboxes/INBOX/threads/thread-1',
+          overrides: [
+            accountRepositoryProvider.overrideWithValue(
+              FakeAccountRepository([kTestAccount]),
+            ),
+            mailboxRepositoryProvider.overrideWithValue(
+              FakeMailboxRepository(),
+            ),
+            emailRepositoryProvider.overrideWithValue(
+              FakeEmailRepository(
+                emails: [email],
+                emailBody: const EmailBody(
+                  emailId: 'acc-1:10',
+                  textBody: 'Body content here',
+                  attachments: [],
+                ),
+              ),
+            ),
+          ],
+        ),
+      );
+      await tester.pumpAndSettle();
+
+      expect(find.text('Body content here'), findsOneWidget);
+    });
+  });
+}