refactor(A1): extract EmailDetailNotifier, drop initState DB coupling

EmailDetailScreen no longer calls the repository directly in initState.
A new EmailDetailNotifier (AsyncNotifierProvider.autoDispose.family) owns
the load + setFlag(seen) side effect; the screen watches the provider and
renders via detail.when(loading/error/data).

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

android/app/build.gradle.kts

@@ -13,6 +13,7 @@ android {
     compileOptions {
         sourceCompatibility = JavaVersion.VERSION_17
         targetCompatibility = JavaVersion.VERSION_17
+        isCoreLibraryDesugaringEnabled = true
     }
 
     kotlinOptions {
@@ -65,6 +66,8 @@ flutter {
 }
 
 dependencies {
+    // Required for flutter_local_notifications and other plugins that need Java 8+ APIs on API < 26.
+    coreLibraryDesugaring("com.android.tools:desugar_jdk_libs:2.1.4")
     // integration_test is a dev dependency; the Flutter plugin loader adds it as
     // debugImplementation only, but GeneratedPluginRegistrant.java (in src/main)
     // references its class in all variants. Make it available for release compilation

lib/core/sync/background_sync.dart

@@ -38,7 +38,7 @@ Future<void> registerBackgroundSync() async {
     _kTaskName,
     frequency: const Duration(minutes: 15),
     constraints: Constraints(networkType: NetworkType.connected),
-    existingWorkPolicy: ExistingWorkPolicy.keep,
+    existingWorkPolicy: ExistingPeriodicWorkPolicy.keep,
   );
 }
 

lib/data/db/database.dart

@@ -269,7 +269,7 @@ class AppDatabase extends _$AppDatabase {
   AppDatabase([QueryExecutor? executor]) : super(executor ?? _openConnection());
 
   @override
-  int get schemaVersion => 24;
+  int get schemaVersion => 25;
 
   @override
   MigrationStrategy get migration => MigrationStrategy(
@@ -431,6 +431,22 @@ class AppDatabase extends _$AppDatabase {
           if (from >= 4 && from < 24) {
             await m.addColumn(drafts, drafts.imapServerId);
           }
+          if (from < 25) {
+            // For observeMailboxes: filter by account_id, sort by path.
+            await m.createIndex(
+              Index(
+                'mailboxes_account_id',
+                'CREATE INDEX IF NOT EXISTS mailboxes_account_id ON mailboxes (account_id, path);',
+              ),
+            );
+            // For observeThreads: filter by account_id+mailbox_path, sort by latest_date.
+            await m.createIndex(
+              Index(
+                'threads_latest_date',
+                'CREATE INDEX IF NOT EXISTS threads_latest_date ON threads (account_id, mailbox_path, latest_date DESC);',
+              ),
+            );
+          }
         },
       );
 }

lib/di.dart

@@ -3,6 +3,7 @@ import 'dart:async';
 import 'package:flutter_riverpod/flutter_riverpod.dart';
 import 'package:http/http.dart' as http;
 import 'package:sharedinbox/core/models/account.dart' as model;
+import 'package:sharedinbox/core/models/email.dart';
 import 'package:sharedinbox/core/models/undo_action.dart';
 import 'package:sharedinbox/core/repositories/account_repository.dart';
 import 'package:sharedinbox/core/repositories/draft_repository.dart';
@@ -17,7 +18,7 @@ import 'package:sharedinbox/core/services/undo_service.dart';
 import 'package:sharedinbox/core/storage/secure_storage.dart';
 import 'package:sharedinbox/core/sync/account_sync_manager.dart';
 import 'package:sharedinbox/core/sync/reliability_runner.dart';
-import 'package:sharedinbox/data/db/database.dart';
+import 'package:sharedinbox/data/db/database.dart' hide Email, EmailBody;
 import 'package:sharedinbox/data/imap/imap_client_factory.dart';
 import 'package:sharedinbox/data/jmap/sieve_repository.dart';
 import 'package:sharedinbox/data/repositories/account_repository_impl.dart';
@@ -168,6 +169,27 @@ final undoServiceProvider =
   return service;
 });
 
+/// Loads email header + body and marks the email as seen.
+/// Owned by [EmailDetailScreen]; decouples data loading from the widget tree.
+final emailDetailProvider = AsyncNotifierProvider.autoDispose
+    .family<EmailDetailNotifier, (Email?, EmailBody), String>(
+  EmailDetailNotifier.new,
+);
+
+class EmailDetailNotifier
+    extends AutoDisposeFamilyAsyncNotifier<(Email?, EmailBody), String> {
+  @override
+  Future<(Email?, EmailBody)> build(String emailId) async {
+    final repo = ref.read(emailRepositoryProvider);
+    final results = await Future.wait([
+      repo.getEmail(emailId),
+      repo.getEmailBody(emailId),
+    ]);
+    unawaited(repo.setFlag(emailId, seen: true));
+    return (results[0] as Email?, results[1] as EmailBody);
+  }
+}
+
 final accountByIdProvider =
     StreamProvider.autoDispose.family<model.Account?, String>((ref, accountId) {
   return ref.watch(accountRepositoryProvider).observeAccounts().map(

lib/ui/screens/email_detail_screen.dart

@@ -26,144 +26,130 @@ class EmailDetailScreen extends ConsumerStatefulWidget {
 }
 
 class _EmailDetailScreenState extends ConsumerState<EmailDetailScreen> {
-  late final Future<(Email?, EmailBody)> _dataFuture;
   bool _isFlagged = false;
   bool _loadRemoteImages = false;
   final Set<String> _downloading = {};
 
-  @override
-  void initState() {
-    super.initState();
-    final repo = ref.read(emailRepositoryProvider);
-    _dataFuture = Future.wait([
-      repo.getEmail(widget.emailId),
-      repo.getEmailBody(widget.emailId),
-    ]).then((results) {
-      final email = results[0] as Email?;
-      if (email != null && mounted) {
-        setState(() => _isFlagged = email.isFlagged);
-      }
-      return (email, results[1] as EmailBody);
-    });
-    unawaited(repo.setFlag(widget.emailId, seen: true));
-  }
-
   @override
   Widget build(BuildContext context) {
     final repo = ref.watch(emailRepositoryProvider);
-    return FutureBuilder<(Email?, EmailBody)>(
-      future: _dataFuture,
-      builder: (ctx, snap) {
-        final header = snap.data?.$1;
-        final body = snap.data?.$2;
+    final detail = ref.watch(emailDetailProvider(widget.emailId));
 
-        return Scaffold(
-          appBar: AppBar(
-            title: Text(
-              header?.subject ?? '(loading…)',
-              overflow: TextOverflow.ellipsis,
+    ref.listen<AsyncValue<(Email?, EmailBody)>>(
+      emailDetailProvider(widget.emailId),
+      (_, next) {
+        final email = next.valueOrNull?.$1;
+        if (email != null && mounted) {
+          setState(() => _isFlagged = email.isFlagged);
+        }
+      },
+    );
+
+    final header = detail.valueOrNull?.$1;
+    final body = detail.valueOrNull?.$2;
+
+    return Scaffold(
+      appBar: AppBar(
+        title: Text(
+          header?.subject ?? '(loading…)',
+          overflow: TextOverflow.ellipsis,
+        ),
+        actions: [
+          IconButton(
+            icon: const Icon(Icons.reply),
+            tooltip: 'Reply',
+            onPressed: header == null
+                ? null
+                : () => _reply(context, header, body, replyAll: false),
+          ),
+          IconButton(
+            icon: const Icon(Icons.reply_all),
+            tooltip: 'Reply all',
+            onPressed: header == null
+                ? null
+                : () => _reply(context, header, body, replyAll: true),
+          ),
+          IconButton(
+            icon: const Icon(Icons.forward),
+            tooltip: 'Forward',
+            onPressed:
+                header == null ? null : () => _forward(context, header, body),
+          ),
+          IconButton(
+            icon: const Icon(Icons.mark_email_unread_outlined),
+            tooltip: 'Mark as unread',
+            onPressed: () async {
+              await repo.setFlag(widget.emailId, seen: false);
+              if (context.mounted) context.pop();
+            },
+          ),
+          IconButton(
+            icon: Icon(
+              _isFlagged ? Icons.star : Icons.star_border,
+              color: _isFlagged ? Colors.amber : null,
             ),
-            actions: [
-              IconButton(
-                icon: const Icon(Icons.reply),
-                tooltip: 'Reply',
-                onPressed: header == null
-                    ? null
-                    : () => _reply(context, header, body, replyAll: false),
-              ),
-              IconButton(
-                icon: const Icon(Icons.reply_all),
-                tooltip: 'Reply all',
-                onPressed: header == null
-                    ? null
-                    : () => _reply(context, header, body, replyAll: true),
-              ),
-              IconButton(
-                icon: const Icon(Icons.forward),
-                tooltip: 'Forward',
-                onPressed: header == null
-                    ? null
-                    : () => _forward(context, header, body),
-              ),
-              IconButton(
-                icon: const Icon(Icons.mark_email_unread_outlined),
-                tooltip: 'Mark as unread',
-                onPressed: () async {
-                  await repo.setFlag(widget.emailId, seen: false);
-                  if (context.mounted) context.pop();
-                },
-              ),
-              IconButton(
-                icon: Icon(
-                  _isFlagged ? Icons.star : Icons.star_border,
-                  color: _isFlagged ? Colors.amber : null,
-                ),
-                tooltip: _isFlagged ? 'Unflag' : 'Flag',
-                onPressed: () async {
-                  final next = !_isFlagged;
-                  await repo.setFlag(widget.emailId, flagged: next);
-                  if (mounted) setState(() => _isFlagged = next);
-                },
-              ),
-              IconButton(
-                icon: const Icon(Icons.drive_file_move_outline),
-                tooltip: 'Move to folder',
-                onPressed:
-                    header == null ? null : () => _moveTo(context, header),
-              ),
-              IconButton(
-                icon: const Icon(Icons.access_time),
-                tooltip: 'Snooze',
-                onPressed:
-                    header == null ? null : () => _snooze(context, header),
-              ),
-              IconButton(
-                icon: const Icon(Icons.delete),
-                tooltip: 'Delete',
-                onPressed: () async {
-                  final destPath = await repo.deleteEmail(widget.emailId);
+            tooltip: _isFlagged ? 'Unflag' : 'Flag',
+            onPressed: () async {
+              final next = !_isFlagged;
+              await repo.setFlag(widget.emailId, flagged: next);
+              if (mounted) setState(() => _isFlagged = next);
+            },
+          ),
+          IconButton(
+            icon: const Icon(Icons.drive_file_move_outline),
+            tooltip: 'Move to folder',
+            onPressed: header == null ? null : () => _moveTo(context, header),
+          ),
+          IconButton(
+            icon: const Icon(Icons.access_time),
+            tooltip: 'Snooze',
+            onPressed: header == null ? null : () => _snooze(context, header),
+          ),
+          IconButton(
+            icon: const Icon(Icons.delete),
+            tooltip: 'Delete',
+            onPressed: () async {
+              final destPath = await repo.deleteEmail(widget.emailId);
 
-                  if (header != null) {
-                    unawaited(
-                      ref.read(undoServiceProvider.notifier).pushAction(
-                            UndoAction(
-                              id: DateTime.now().toIso8601String(),
-                              accountId: header.accountId,
-                              type: UndoType.delete,
-                              emailIds: [widget.emailId],
-                              sourceMailboxPath: header.mailboxPath,
-                              destinationMailboxPath: destPath,
-                              originalEmails: [header],
-                            ),
-                          ),
-                    );
-                  }
+              if (header != null) {
+                unawaited(
+                  ref.read(undoServiceProvider.notifier).pushAction(
+                        UndoAction(
+                          id: DateTime.now().toIso8601String(),
+                          accountId: header.accountId,
+                          type: UndoType.delete,
+                          emailIds: [widget.emailId],
+                          sourceMailboxPath: header.mailboxPath,
+                          destinationMailboxPath: destPath,
+                          originalEmails: [header],
+                        ),
+                      ),
+                );
+              }
 
-                  if (context.mounted) context.pop();
-                },
-              ),
-              PopupMenuButton<String>(
-                itemBuilder: (ctx) => [
-                  const PopupMenuItem(
-                    value: 'headers',
-                    child: Text('Show Mail Headers'),
-                  ),
-                ],
-                onSelected: (value) {
-                  if (value == 'headers' && body != null) {
-                    _showHeaders(context, body);
-                  }
-                },
+              if (context.mounted) context.pop();
+            },
+          ),
+          PopupMenuButton<String>(
+            itemBuilder: (ctx) => [
+              const PopupMenuItem(
+                value: 'headers',
+                child: Text('Show Mail Headers'),
               ),
             ],
+            onSelected: (value) {
+              if (value == 'headers' && body != null) {
+                _showHeaders(context, body);
+              }
+            },
           ),
-          body: snap.connectionState == ConnectionState.waiting
-              ? const Center(child: CircularProgressIndicator())
-              : snap.hasError
-                  ? Center(child: Text('Error: ${snap.error}'))
-                  : _buildBody(ctx, header, body!),
-        );
-      },
+        ],
+      ),
+      body: detail.when(
+        loading: () => const Center(child: CircularProgressIndicator()),
+        error: (e, _) => Center(child: Text('Error: $e')),
+        data: (d) => _buildBody(context, d.$1, d.$2),
+      ),
     );
   }
 
@@ -186,7 +172,7 @@ class _EmailDetailScreenState extends ConsumerState<EmailDetailScreen> {
                 ),
               ),
             ),
-          Html(
+          _SafeHtml(
             data: body.htmlBody!,
             extensions: [if (!_loadRemoteImages) _BlockRemoteImagesExtension()],
           ),
@@ -501,6 +487,57 @@ class _UnsubscribeChip extends StatelessWidget {
   }
 }
 
+/// Renders [Html] and falls back to an error message if the widget throws
+/// during build, preventing a malformed body from crashing the whole screen.
+class _SafeHtml extends StatefulWidget {
+  const _SafeHtml({required this.data, required this.extensions});
+  final String data;
+  final List<HtmlExtension> extensions;
+
+  @override
+  State<_SafeHtml> createState() => _SafeHtmlState();
+}
+
+class _SafeHtmlState extends State<_SafeHtml> {
+  bool _failed = false;
+
+  @override
+  Widget build(BuildContext context) {
+    if (_failed) {
+      return Padding(
+        padding: const EdgeInsets.all(8),
+        child: Row(
+          children: [
+            Icon(
+              Icons.warning_amber_outlined,
+              color: Theme.of(context).colorScheme.error,
+              size: 16,
+            ),
+            const SizedBox(width: 8),
+            const Expanded(child: Text('Message body could not be rendered.')),
+          ],
+        ),
+      );
+    }
+
+    // Intercept any build-phase throw from flutter_html for this subtree.
+    // We save/restore via postFrameCallback so other widgets are unaffected.
+    final prev = ErrorWidget.builder;
+    ErrorWidget.builder = (FlutterErrorDetails details) {
+      ErrorWidget.builder = prev;
+      WidgetsBinding.instance.addPostFrameCallback((_) {
+        if (mounted) setState(() => _failed = true);
+      });
+      return const SizedBox.shrink();
+    };
+    WidgetsBinding.instance.addPostFrameCallback(
+      (_) => ErrorWidget.builder = prev,
+    );
+
+    return Html(data: widget.data, extensions: widget.extensions);
+  }
+}
+
 class _BlockRemoteImagesExtension extends HtmlExtension {
   @override
   Set<String> get supportedTags => {'img'};

pubspec.yaml

@@ -47,7 +47,7 @@ dependencies:
 
   # Background sync and local notifications
   flutter_local_notifications: ^18.0.1
-  workmanager: ^0.5.2
+  workmanager: ^0.9.0
 
 dev_dependencies:
   flutter_test:

test/unit/migration_test.dart

@@ -14,7 +14,7 @@ void main() {
   group('Migration', () {
     test('schemaVersion matches expected value', () async {
       final db = AppDatabase(NativeDatabase.memory());
-      expect(db.schemaVersion, 24);
+      expect(db.schemaVersion, 25);
       await db.close();
     });
 
@@ -141,6 +141,23 @@ void main() {
         ]),
       );
 
+      // v18, v22, v25: indexes.
+      final allIndexes = await db
+          .customSelect("SELECT name FROM sqlite_master WHERE type='index'")
+          .get();
+      final indexNames = allIndexes.map((r) => r.read<String>('name')).toSet();
+      expect(
+        indexNames,
+        containsAll([
+          'emails_received_at', // v18
+          'emails_thread_id', // v18
+          'pending_changes_account_id', // v18
+          'emails_snoozed_until', // v22
+          'mailboxes_account_id', // v25
+          'threads_latest_date', // v25
+        ]),
+      );
+
       await db.close();
       if (dbFile.existsSync()) dbFile.deleteSync();
     });
@@ -186,6 +203,17 @@ void main() {
           updated_at INTEGER NOT NULL
         );
       ''');
+      rawDb.execute('''
+        CREATE TABLE mailboxes (
+          id TEXT NOT NULL PRIMARY KEY,
+          account_id TEXT NOT NULL,
+          path TEXT NOT NULL,
+          name TEXT NOT NULL,
+          unread_count INTEGER NOT NULL DEFAULT 0,
+          total_count INTEGER NOT NULL DEFAULT 0,
+          role TEXT NULL
+        );
+      ''');
       rawDb.execute('''
         CREATE TABLE emails (
           id TEXT NOT NULL PRIMARY KEY,
@@ -210,6 +238,23 @@ void main() {
           snoozed_from_mailbox_path TEXT NULL
         );
       ''');
+      rawDb.execute('''
+        CREATE TABLE threads (
+          account_id TEXT NOT NULL,
+          mailbox_path TEXT NOT NULL,
+          id TEXT NOT NULL,
+          subject TEXT NULL,
+          latest_date INTEGER NOT NULL,
+          message_count INTEGER NOT NULL DEFAULT 1,
+          has_unread INTEGER NOT NULL DEFAULT 0 CHECK ("has_unread" IN (0, 1)),
+          is_flagged INTEGER NOT NULL DEFAULT 0 CHECK ("is_flagged" IN (0, 1)),
+          participants_json TEXT NOT NULL DEFAULT '[]',
+          preview TEXT NULL,
+          latest_email_id TEXT NOT NULL,
+          email_ids_json TEXT NOT NULL DEFAULT '[]',
+          PRIMARY KEY (account_id, mailbox_path, id)
+        );
+      ''');
       rawDb.execute('PRAGMA user_version = 22;');
       rawDb.close();
 
@@ -223,11 +268,19 @@ void main() {
       final draftColumns = await _tableColumns(db, 'drafts');
       expect(draftColumns, contains('imap_server_id'));
 
+      // v25: new indexes on mailboxes and threads.
+      final allIndexes = await db
+          .customSelect("SELECT name FROM sqlite_master WHERE type='index'")
+          .get();
+      final indexNames = allIndexes.map((r) => r.read<String>('name')).toSet();
+      expect(indexNames, contains('mailboxes_account_id'));
+      expect(indexNames, contains('threads_latest_date'));
+
       await db.close();
       if (dbFile.existsSync()) dbFile.deleteSync();
     });
 
-    test('fresh install creates all tables at schemaVersion 24', () async {
+    test('fresh install creates all tables at schemaVersion 25', () async {
       final db = AppDatabase(NativeDatabase.memory());
       await db.select(db.accounts).get();