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>

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

@@ -26,36 +26,27 @@ 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?;
+  Widget build(BuildContext context) {
+    final repo = ref.watch(emailRepositoryProvider);
+    final detail = ref.watch(emailDetailProvider(widget.emailId));
+
+    ref.listen<AsyncValue<(Email?, EmailBody)>>(
+      emailDetailProvider(widget.emailId),
+      (_, next) {
+        final email = next.valueOrNull?.$1;
         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 header = detail.valueOrNull?.$1;
+    final body = detail.valueOrNull?.$2;
 
     return Scaffold(
       appBar: AppBar(
@@ -81,9 +72,8 @@ class _EmailDetailScreenState extends ConsumerState<EmailDetailScreen> {
           IconButton(
             icon: const Icon(Icons.forward),
             tooltip: 'Forward',
-                onPressed: header == null
-                    ? null
-                    : () => _forward(context, header, body),
+            onPressed:
+                header == null ? null : () => _forward(context, header, body),
           ),
           IconButton(
             icon: const Icon(Icons.mark_email_unread_outlined),
@@ -108,14 +98,12 @@ class _EmailDetailScreenState extends ConsumerState<EmailDetailScreen> {
           IconButton(
             icon: const Icon(Icons.drive_file_move_outline),
             tooltip: 'Move to folder',
-                onPressed:
-                    header == null ? null : () => _moveTo(context, header),
+            onPressed: header == null ? null : () => _moveTo(context, header),
           ),
           IconButton(
             icon: const Icon(Icons.access_time),
             tooltip: 'Snooze',
-                onPressed:
-                    header == null ? null : () => _snooze(context, header),
+            onPressed: header == null ? null : () => _snooze(context, header),
           ),
           IconButton(
             icon: const Icon(Icons.delete),
@@ -157,13 +145,11 @@ class _EmailDetailScreenState extends ConsumerState<EmailDetailScreen> {
           ),
         ],
       ),
-          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),
+      ),
     );
   }