diff --git a/LATER.md b/LATER.md
index 6e1ee5f..2f30ba9 100644
--- a/LATER.md
+++ b/LATER.md
@@ -31,12 +31,6 @@ Try Qwen, vscode plugin
 
 ---
 
-test/unit/fake_imap.dart
-
-Why is that still needed? We have Stalwart.
-
----
-
 After Try Connection, show some matching icon next to the text.
 
 ---
@@ -47,12 +41,6 @@ Test with a Fastmail account
 
 ---
 
-LINTING.md
-
----
-
----
-
 scripts/check_coverage.dart
 reduce files in _excluded.
 
diff --git a/NEXT.md b/NEXT.md
index a5cdb5d..8fb1783 100644
--- a/NEXT.md
+++ b/NEXT.md
@@ -4,12 +4,23 @@
 
 Do one thing, ask if unsure first!
 
-The implement.
+Then implement.
 
 Then run `task check`.
 
+Then move task to DONE.md
+
 Then commit.
 
-After commit, remove the item from this document.
-
 ## Tasks
+
+Implement thread-view.
+
+First create a plan.
+
+For JMAP this is easy.
+
+But for IMAP?
+
+Threads should be synced to the DB, too. Use JMAP as an example. Then think about getting this data
+structure from imap.
diff --git a/lib/core/models/email.dart b/lib/core/models/email.dart
index 3f7ad47..a850659 100644
--- a/lib/core/models/email.dart
+++ b/lib/core/models/email.dart
@@ -14,6 +14,11 @@ class Email {
   final bool isSeen;
   final bool isFlagged;
   final bool hasAttachment;
+  final String? threadId;
+  final String? messageId;
+  final String? inReplyTo;
+  // Space-separated RFC 2822 References header value.
+  final String? references;
 
   const Email({
     required this.id,
@@ -30,6 +35,41 @@ class Email {
     required this.isSeen,
     required this.isFlagged,
     required this.hasAttachment,
+    this.threadId,
+    this.messageId,
+    this.inReplyTo,
+    this.references,
+  });
+}
+
+/// A group of related emails sharing the same thread.
+class EmailThread {
+  final String threadId;
+  final String? subject;
+  final List<EmailAddress> participants;
+  final DateTime latestDate;
+  final int messageCount;
+  final bool hasUnread;
+  final bool isFlagged;
+  final String latestEmailId;
+  final String accountId;
+  final String mailboxPath;
+
+  // All email IDs in this thread (oldest-first). Needed for batch operations.
+  final List<String> emailIds;
+
+  const EmailThread({
+    required this.threadId,
+    required this.subject,
+    required this.participants,
+    required this.latestDate,
+    required this.messageCount,
+    required this.hasUnread,
+    required this.isFlagged,
+    required this.latestEmailId,
+    required this.emailIds,
+    required this.accountId,
+    required this.mailboxPath,
   });
 }
 
diff --git a/lib/core/repositories/email_repository.dart b/lib/core/repositories/email_repository.dart
index c898655..bfa20fc 100644
--- a/lib/core/repositories/email_repository.dart
+++ b/lib/core/repositories/email_repository.dart
@@ -2,6 +2,13 @@ import '../models/email.dart';
 
 abstract class EmailRepository {
   Stream<List<Email>> observeEmails(String accountId, String mailboxPath);
+
+  /// Groups emails by threadId and returns one [EmailThread] per thread,
+  /// sorted by the latest message date descending.
+  Stream<List<EmailThread>> observeThreads(
+    String accountId,
+    String mailboxPath,
+  );
   Future<Email?> getEmail(String emailId);
   Future<EmailBody> getEmailBody(String emailId);
   Future<SyncEmailsResult> syncEmails(String accountId, String mailboxPath);
diff --git a/lib/data/db/database.dart b/lib/data/db/database.dart
index 324b121..bf4cad4 100644
--- a/lib/data/db/database.dart
+++ b/lib/data/db/database.dart
@@ -65,6 +65,12 @@ class Emails extends Table {
   BoolColumn get isFlagged => boolean().withDefault(const Constant(false))();
   BoolColumn get hasAttachment =>
       boolean().withDefault(const Constant(false))();
+  // Added in schema v14: email threading.
+  TextColumn get threadId => text().nullable()();
+  TextColumn get messageId => text().nullable()();
+  TextColumn get inReplyTo => text().nullable()();
+  // Space-separated list of Message-IDs (RFC 2822 References header).
+  TextColumn get references => text().nullable()();
 
   @override
   Set<Column> get primaryKey => {id};
@@ -189,7 +195,7 @@ class AppDatabase extends _$AppDatabase {
   AppDatabase([QueryExecutor? executor]) : super(executor ?? _openConnection());
 
   @override
-  int get schemaVersion => 13;
+  int get schemaVersion => 14;
 
   @override
   MigrationStrategy get migration => MigrationStrategy(
@@ -235,6 +241,12 @@ class AppDatabase extends _$AppDatabase {
             await m.addColumn(accounts, accounts.verbose);
             await m.addColumn(syncLogs, syncLogs.protocolLog);
           }
+          if (from < 14) {
+            await m.addColumn(emails, emails.threadId);
+            await m.addColumn(emails, emails.messageId);
+            await m.addColumn(emails, emails.inReplyTo);
+            await m.addColumn(emails, emails.references);
+          }
         },
       );
 }
diff --git a/lib/data/repositories/email_repository_impl.dart b/lib/data/repositories/email_repository_impl.dart
index 8c980c8..514ec94 100644
--- a/lib/data/repositories/email_repository_impl.dart
+++ b/lib/data/repositories/email_repository_impl.dart
@@ -66,6 +66,61 @@ class EmailRepositoryImpl implements EmailRepository {
         .map((rows) => rows.map(_toModel).toList());
   }
 
+  @override
+  Stream<List<model.EmailThread>> observeThreads(
+    String accountId,
+    String mailboxPath,
+  ) {
+    return observeEmails(accountId, mailboxPath).map(_groupIntoThreads);
+  }
+
+  static List<model.EmailThread> _groupIntoThreads(List<model.Email> emails) {
+    // Group emails by threadId, falling back to email id for unthreaded mail.
+    final groups = <String, List<model.Email>>{};
+    for (final email in emails) {
+      final key = email.threadId ?? email.id;
+      groups.putIfAbsent(key, () => []).add(email);
+    }
+
+    final threads = groups.values.map((threadEmails) {
+      // Sort within thread oldest-first so latest is last.
+      threadEmails.sort((a, b) {
+        final da = a.sentAt ?? a.receivedAt;
+        final db = b.sentAt ?? b.receivedAt;
+        return da.compareTo(db);
+      });
+
+      final latest = threadEmails.last;
+
+      // Collect unique participants across the whole thread.
+      final seen = <String>{};
+      final participants = <model.EmailAddress>[];
+      for (final e in threadEmails) {
+        for (final a in e.from) {
+          if (seen.add(a.email)) participants.add(a);
+        }
+      }
+
+      return model.EmailThread(
+        threadId: latest.threadId ?? latest.id,
+        subject: latest.subject,
+        participants: participants,
+        latestDate: latest.sentAt ?? latest.receivedAt,
+        messageCount: threadEmails.length,
+        hasUnread: threadEmails.any((e) => !e.isSeen),
+        isFlagged: threadEmails.any((e) => e.isFlagged),
+        latestEmailId: latest.id,
+        emailIds: threadEmails.map((e) => e.id).toList(),
+        accountId: latest.accountId,
+        mailboxPath: latest.mailboxPath,
+      );
+    }).toList();
+
+    // Sort threads by latest message descending.
+    threads.sort((a, b) => b.latestDate.compareTo(a.latestDate));
+    return threads;
+  }
+
   @override
   Future<model.Email?> getEmail(String emailId) async {
     final row = await (_db.select(_db.emails)
@@ -383,15 +438,11 @@ class EmailRepositoryImpl implements EmailRepository {
     String mailboxPath,
     imap.MessageSequence sequence,
   ) async {
+    const fetchItems =
+        '(UID FLAGS ENVELOPE BODYSTRUCTURE RFC822.SIZE BODY.PEEK[HEADER.FIELDS (REFERENCES)])';
     final fetch = sequence.isUidSequence
-        ? await client.uidFetchMessages(
-            sequence,
-            '(UID FLAGS ENVELOPE BODYSTRUCTURE RFC822.SIZE)',
-          )
-        : await client.fetchMessages(
-            sequence,
-            '(UID FLAGS ENVELOPE BODYSTRUCTURE RFC822.SIZE)',
-          );
+        ? await client.uidFetchMessages(sequence, fetchItems)
+        : await client.fetchMessages(sequence, fetchItems);
     var bytes = 0;
     await _db.transaction(() async {
       for (final msg in fetch.messages) {
@@ -407,6 +458,15 @@ class EmailRepositoryImpl implements EmailRepository {
         }
         bytes += msg.size ?? 0;
         final emailId = '${account.id}:$uid';
+        final msgId = envelope.messageId?.trim();
+        final inReplyTo = envelope.inReplyTo?.trim();
+        final refs = msg.getHeaderValue('References')?.trim();
+        final threadId = _computeThreadId(
+          emailId: emailId,
+          messageId: msgId,
+          inReplyTo: inReplyTo,
+          references: refs,
+        );
         await _db.into(_db.emails).insertOnConflictUpdate(
               EmailsCompanion.insert(
                 id: emailId,
@@ -422,6 +482,10 @@ class EmailRepositoryImpl implements EmailRepository {
                 isSeen: Value(msg.flags?.contains(r'\Seen') ?? false),
                 isFlagged: Value(msg.flags?.contains(r'\Flagged') ?? false),
                 hasAttachment: Value(msg.hasAttachments()),
+                threadId: Value(threadId),
+                messageId: Value(msgId),
+                inReplyTo: Value(inReplyTo),
+                references: Value(refs),
               ),
             );
       }
@@ -495,6 +559,7 @@ class EmailRepositoryImpl implements EmailRepository {
 
   static const _emailProperties = [
     'id',
+    'threadId',
     'mailboxIds',
     'subject',
     'sentAt',
@@ -505,6 +570,9 @@ class EmailRepositoryImpl implements EmailRepository {
     'keywords',
     'hasAttachment',
     'preview',
+    'messageId',
+    'inReplyTo',
+    'references',
     'textBody',
     'htmlBody',
     'bodyValues',
@@ -678,6 +746,15 @@ class EmailRepositoryImpl implements EmailRepository {
       final receivedAt =
           _parseDate(m['receivedAt'] as String?) ?? DateTime.now();
 
+      final jmapThreadId = m['threadId'] as String?;
+      // JMAP messageId/inReplyTo/references are arrays; join to space-separated.
+      final jmapMessageId =
+          _joinJmapStringList(m['messageId'] as List<dynamic>?);
+      final jmapInReplyTo =
+          _joinJmapStringList(m['inReplyTo'] as List<dynamic>?);
+      final jmapReferences =
+          _joinJmapStringList(m['references'] as List<dynamic>?);
+
       await _db.into(_db.emails).insertOnConflictUpdate(
             EmailsCompanion.insert(
               id: dbId,
@@ -694,6 +771,10 @@ class EmailRepositoryImpl implements EmailRepository {
               isSeen: Value(keywords.containsKey(r'$seen')),
               isFlagged: Value(keywords.containsKey(r'$flagged')),
               hasAttachment: Value((m['hasAttachment'] as bool?) ?? false),
+              threadId: Value(jmapThreadId),
+              messageId: Value(jmapMessageId),
+              inReplyTo: Value(jmapInReplyTo),
+              references: Value(jmapReferences),
             ),
           );
 
@@ -1728,6 +1809,32 @@ class EmailRepositoryImpl implements EmailRepository {
 
   // ── Helpers ────────────────────────────────────────────────────────────────
 
+  /// Computes a stable threadId from RFC 2822 headers.
+  /// Uses the first entry in References (= oldest ancestor) so all messages
+  /// in a thread share the same root Message-ID as their threadId.
+  /// Falls back to In-Reply-To, then own Message-ID, then internal emailId.
+  /// JMAP header fields like messageId/inReplyTo/references come as arrays.
+  /// We join them space-separated to match the IMAP convention.
+  static String? _joinJmapStringList(List<dynamic>? list) {
+    if (list == null || list.isEmpty) return null;
+    final joined = list.cast<String>().join(' ');
+    return joined.isEmpty ? null : joined;
+  }
+
+  static String? _computeThreadId({
+    required String emailId,
+    required String? messageId,
+    required String? inReplyTo,
+    required String? references,
+  }) {
+    if (references != null && references.isNotEmpty) {
+      final first = references.trim().split(RegExp(r'\s+')).firstOrNull;
+      if (first != null && first.isNotEmpty) return first;
+    }
+    if (inReplyTo != null && inReplyTo.isNotEmpty) return inReplyTo;
+    return messageId; // null for messages with no Message-ID (rare)
+  }
+
   String _encodeAddresses(List<imap.MailAddress>? addresses) => jsonEncode(
         (addresses ?? const [])
             .map((a) => {'name': a.personalName, 'email': a.email})
@@ -1762,6 +1869,10 @@ class EmailRepositoryImpl implements EmailRepository {
       isSeen: row.isSeen,
       isFlagged: row.isFlagged,
       hasAttachment: row.hasAttachment,
+      threadId: row.threadId,
+      messageId: row.messageId,
+      inReplyTo: row.inReplyTo,
+      references: row.references,
     );
   }
 
diff --git a/lib/ui/router.dart b/lib/ui/router.dart
index 71e4d20..f9bf8af 100644
--- a/lib/ui/router.dart
+++ b/lib/ui/router.dart
@@ -14,6 +14,7 @@ import 'screens/search_screen.dart';
 import 'screens/sieve_script_edit_screen.dart';
 import 'screens/sieve_scripts_screen.dart';
 import 'screens/sync_log_screen.dart';
+import 'screens/thread_detail_screen.dart';
 
 final router = GoRouter(
   initialLocation: '/accounts',
@@ -84,6 +85,18 @@ final router = GoRouter(
                 ),
               ],
             ),
+            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']!,
+                ),
+              ),
+            ),
           ],
         ),
       ],
diff --git a/lib/ui/screens/email_list_screen.dart b/lib/ui/screens/email_list_screen.dart
index 108a1db..e12d56d 100644
--- a/lib/ui/screens/email_list_screen.dart
+++ b/lib/ui/screens/email_list_screen.dart
@@ -31,8 +31,11 @@ class _EmailListScreenState extends ConsumerState<EmailListScreen> {
   List<Email>? _searchResults;
   bool _searchLoading = false;
 
-  final Set<String> _selectedIds = {};
-  bool get _selecting => _selectedIds.isNotEmpty;
+  // Thread-level selection (key = threadId).
+  final Set<String> _selectedThreadIds = {};
+  // Last-emitted thread list, used to resolve emailIds for batch operations.
+  List<EmailThread> _currentThreads = [];
+  bool get _selecting => _selectedThreadIds.isNotEmpty;
 
   @override
   void dispose() {
@@ -40,17 +43,23 @@ class _EmailListScreenState extends ConsumerState<EmailListScreen> {
     super.dispose();
   }
 
-  void _toggleSelection(String id) {
+  void _toggleThreadSelection(EmailThread thread) {
     setState(() {
-      if (_selectedIds.contains(id)) {
-        _selectedIds.remove(id);
+      if (_selectedThreadIds.contains(thread.threadId)) {
+        _selectedThreadIds.remove(thread.threadId);
       } else {
-        _selectedIds.add(id);
+        _selectedThreadIds.add(thread.threadId);
       }
     });
   }
 
-  void _clearSelection() => setState(() => _selectedIds.clear());
+  void _clearSelection() => setState(() => _selectedThreadIds.clear());
+
+  // All email IDs belonging to currently selected threads.
+  List<String> get _selectedEmailIds => _currentThreads
+      .where((t) => _selectedThreadIds.contains(t.threadId))
+      .expand((t) => t.emailIds)
+      .toList();
 
   Future<void> _runSearch(String query) async {
     if (query.trim().isEmpty) {
@@ -144,7 +153,7 @@ class _EmailListScreenState extends ConsumerState<EmailListScreen> {
         icon: const Icon(Icons.close),
         onPressed: _clearSelection,
       ),
-      title: Text('${_selectedIds.length} selected'),
+      title: Text('${_selectedThreadIds.length} selected'),
     );
   }
 
@@ -217,45 +226,28 @@ class _EmailListScreenState extends ConsumerState<EmailListScreen> {
     if (_searchResults!.isEmpty) {
       return const Center(child: Text('No results'));
     }
-    return _buildList(_searchResults!);
+    return _buildEmailList(_searchResults!);
   }
 
   Widget _buildStreamBody(EmailRepository emailRepo) {
-    return StreamBuilder<List<Email>>(
-      stream: emailRepo.observeEmails(widget.accountId, widget.mailboxPath),
+    return StreamBuilder<List<EmailThread>>(
+      stream: emailRepo.observeThreads(widget.accountId, widget.mailboxPath),
       builder: (ctx, snap) {
         if (!snap.hasData) {
           return const Center(child: CircularProgressIndicator());
         }
-        final emails = snap.data!;
-        if (emails.isEmpty) {
+        final threads = snap.data!;
+        _currentThreads = threads;
+        if (threads.isEmpty) {
           return const Center(child: Text('No emails'));
         }
-        return _buildList(emails);
+        return _buildThreadList(threads);
       },
     );
   }
 
-  Future<void> _archiveEmail(Email email) async {
-    final archive = await ref
-        .read(mailboxRepositoryProvider)
-        .findMailboxByRole(widget.accountId, 'archive');
-    if (!mounted) return;
-    if (archive == null) {
-      ScaffoldMessenger.of(context).showSnackBar(
-        const SnackBar(content: Text('No archive folder found')),
-      );
-      return;
-    }
-    await ref.read(emailRepositoryProvider).moveEmail(email.id, archive.path);
-  }
-
-  Future<void> _deleteEmail(Email email) async {
-    await ref.read(emailRepositoryProvider).deleteEmail(email.id);
-  }
-
   Future<void> _batchArchive() async {
-    final ids = Set<String>.from(_selectedIds);
+    final ids = _selectedEmailIds;
     _clearSelection();
     final archive = await ref
         .read(mailboxRepositoryProvider)
@@ -274,7 +266,7 @@ class _EmailListScreenState extends ConsumerState<EmailListScreen> {
   }
 
   Future<void> _batchDelete() async {
-    final ids = Set<String>.from(_selectedIds);
+    final ids = _selectedEmailIds;
     _clearSelection();
     final repo = ref.read(emailRepositoryProvider);
     for (final id in ids) {
@@ -283,7 +275,7 @@ class _EmailListScreenState extends ConsumerState<EmailListScreen> {
   }
 
   Future<void> _batchMarkSpam() async {
-    final ids = Set<String>.from(_selectedIds);
+    final ids = _selectedEmailIds;
     _clearSelection();
     final junk = await ref
         .read(mailboxRepositoryProvider)
@@ -302,7 +294,7 @@ class _EmailListScreenState extends ConsumerState<EmailListScreen> {
   }
 
   Future<void> _batchMove() async {
-    final ids = Set<String>.from(_selectedIds);
+    final ids = _selectedEmailIds;
     final mailboxes = await ref
         .read(mailboxRepositoryProvider)
         .observeMailboxes(widget.accountId)
@@ -341,33 +333,48 @@ class _EmailListScreenState extends ConsumerState<EmailListScreen> {
     }
   }
 
-  Widget _buildList(List<Email> emails) {
+  Widget _buildThreadList(List<EmailThread> threads) {
     return ListView.builder(
-      itemCount: emails.length,
+      itemCount: threads.length,
       itemBuilder: (ctx, i) {
-        final e = emails[i];
-        final isSelected = _selectedIds.contains(e.id);
-        final sender = e.from.isNotEmpty
-            ? (e.from.first.name ?? e.from.first.email)
-            : '(unknown)';
+        final t = threads[i];
+        final isSelected = _selectedThreadIds.contains(t.threadId);
+        final senderNames =
+            t.participants.map((a) => a.name ?? a.email).take(3).join(', ');
 
         final tile = ListTile(
           leading: _selecting
               ? Checkbox(
                   value: isSelected,
-                  onChanged: (_) => _toggleSelection(e.id),
+                  onChanged: (_) => _toggleThreadSelection(t),
                 )
               : Icon(
-                  e.isSeen ? Icons.mail_outline : Icons.mail,
-                  color: e.isSeen ? null : Theme.of(ctx).colorScheme.primary,
+                  t.hasUnread ? Icons.mail : Icons.mail_outline,
+                  color: t.hasUnread ? Theme.of(ctx).colorScheme.primary : null,
                 ),
-          title: Text(
-            sender,
-            style:
-                e.isSeen ? null : const TextStyle(fontWeight: FontWeight.bold),
+          title: Row(
+            children: [
+              Expanded(
+                child: Text(
+                  senderNames.isEmpty ? '(unknown)' : senderNames,
+                  style: t.hasUnread
+                      ? const TextStyle(fontWeight: FontWeight.bold)
+                      : null,
+                  overflow: TextOverflow.ellipsis,
+                ),
+              ),
+              if (t.messageCount > 1)
+                Padding(
+                  padding: const EdgeInsets.only(left: 4),
+                  child: Text(
+                    '[${t.messageCount}]',
+                    style: Theme.of(ctx).textTheme.bodySmall,
+                  ),
+                ),
+            ],
           ),
           subtitle: Text(
-            e.subject ?? '(no subject)',
+            t.subject ?? '(no subject)',
             maxLines: 1,
             overflow: TextOverflow.ellipsis,
           ),
@@ -377,29 +384,33 @@ class _EmailListScreenState extends ConsumerState<EmailListScreen> {
               : Row(
                   mainAxisSize: MainAxisSize.min,
                   children: [
-                    if (e.isFlagged)
+                    if (t.isFlagged)
                       const Icon(Icons.star, color: Colors.amber, size: 16),
-                    if (e.hasAttachment)
-                      const Icon(Icons.attach_file, size: 16),
                     const SizedBox(width: 4),
                     Text(
-                      e.sentAt != null ? _dateFmt.format(e.sentAt!) : '',
+                      _dateFmt.format(t.latestDate),
                       style: Theme.of(ctx).textTheme.bodySmall,
                     ),
                   ],
                 ),
           onTap: _selecting
-              ? () => _toggleSelection(e.id)
-              : () => context.push(
-                    '/accounts/${widget.accountId}/mailboxes/${Uri.encodeComponent(widget.mailboxPath)}/emails/${Uri.encodeComponent(e.id)}',
-                  ),
-          onLongPress: () => _toggleSelection(e.id),
+              ? () => _toggleThreadSelection(t)
+              : t.messageCount > 1
+                  ? () => context.push(
+                        '/accounts/${widget.accountId}/mailboxes/${Uri.encodeComponent(widget.mailboxPath)}/threads/${Uri.encodeComponent(t.threadId)}',
+                      )
+                  : () => context.push(
+                        '/accounts/${widget.accountId}/mailboxes/${Uri.encodeComponent(widget.mailboxPath)}/emails/${Uri.encodeComponent(t.latestEmailId)}',
+                      ),
+          onLongPress: () => _toggleThreadSelection(t),
         );
 
         if (_selecting) return tile;
 
+        // For swipe actions on threads, operate on the latest email only
+        // (single-email threads) or the whole thread.
         return Dismissible(
-          key: ValueKey(e.id),
+          key: ValueKey(t.threadId),
           background: _swipeBackground(
             alignment: Alignment.centerLeft,
             color: Colors.green,
@@ -413,10 +424,19 @@ class _EmailListScreenState extends ConsumerState<EmailListScreen> {
             label: 'Delete',
           ),
           onDismissed: (direction) async {
+            final repo = ref.read(emailRepositoryProvider);
             if (direction == DismissDirection.startToEnd) {
-              await _archiveEmail(e);
+              final archive = await ref
+                  .read(mailboxRepositoryProvider)
+                  .findMailboxByRole(widget.accountId, 'archive');
+              if (!mounted || archive == null) return;
+              for (final id in t.emailIds) {
+                await repo.moveEmail(id, archive.path);
+              }
             } else {
-              await _deleteEmail(e);
+              for (final id in t.emailIds) {
+                await repo.deleteEmail(id);
+              }
             }
           },
           child: tile,
@@ -425,6 +445,42 @@ class _EmailListScreenState extends ConsumerState<EmailListScreen> {
     );
   }
 
+  // Used for search results, which are individual emails.
+  Widget _buildEmailList(List<Email> emails) {
+    return ListView.builder(
+      itemCount: emails.length,
+      itemBuilder: (ctx, i) {
+        final e = emails[i];
+        final sender = e.from.isNotEmpty
+            ? (e.from.first.name ?? e.from.first.email)
+            : '(unknown)';
+        return ListTile(
+          leading: 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,
+          ),
+          trailing: Text(
+            e.sentAt != null ? _dateFmt.format(e.sentAt!) : '',
+            style: Theme.of(ctx).textTheme.bodySmall,
+          ),
+          onTap: () => context.push(
+            '/accounts/${widget.accountId}/mailboxes/${Uri.encodeComponent(widget.mailboxPath)}/emails/${Uri.encodeComponent(e.id)}',
+          ),
+        );
+      },
+    );
+  }
+
   Widget _swipeBackground({
     required AlignmentGeometry alignment,
     required Color color,
diff --git a/lib/ui/screens/thread_detail_screen.dart b/lib/ui/screens/thread_detail_screen.dart
new file mode 100644
index 0000000..b42c2bc
--- /dev/null
+++ b/lib/ui/screens/thread_detail_screen.dart
@@ -0,0 +1,101 @@
+import 'package:flutter/material.dart';
+import 'package:flutter_riverpod/flutter_riverpod.dart';
+import 'package:go_router/go_router.dart';
+import 'package:intl/intl.dart';
+
+import '../../core/models/email.dart';
+import '../../di.dart';
+
+final _dateFmt = DateFormat('MMM d');
+
+class ThreadDetailScreen extends ConsumerWidget {
+  const ThreadDetailScreen({
+    super.key,
+    required this.accountId,
+    required this.mailboxPath,
+    required this.threadId,
+  });
+
+  final String accountId;
+  final String mailboxPath;
+  final String threadId;
+
+  @override
+  Widget build(BuildContext context, WidgetRef ref) {
+    final repo = ref.watch(emailRepositoryProvider);
+    return Scaffold(
+      appBar: AppBar(title: const Text('Thread')),
+      body: StreamBuilder<List<EmailThread>>(
+        stream: repo.observeThreads(accountId, mailboxPath),
+        builder: (ctx, snap) {
+          if (!snap.hasData) {
+            return const Center(child: CircularProgressIndicator());
+          }
+          final thread =
+              snap.data!.where((t) => t.threadId == threadId).firstOrNull;
+          if (thread == null) {
+            return const Center(child: Text('Thread not found'));
+          }
+          // Re-fetch the individual emails from observeEmails to show them.
+          return StreamBuilder<List<Email>>(
+            stream: repo.observeEmails(accountId, mailboxPath),
+            builder: (ctx, emailSnap) {
+              if (!emailSnap.hasData) {
+                return const Center(child: CircularProgressIndicator());
+              }
+              final emails = emailSnap.data!
+                  .where(
+                    (e) => (e.threadId ?? e.id) == threadId,
+                  )
+                  .toList()
+                ..sort((a, b) {
+                  final da = a.sentAt ?? a.receivedAt;
+                  final db = b.sentAt ?? b.receivedAt;
+                  return da.compareTo(db);
+                });
+
+              if (emails.isEmpty) {
+                return const Center(child: Text('No messages'));
+              }
+
+              return ListView.builder(
+                itemCount: emails.length,
+                itemBuilder: (ctx, i) {
+                  final e = emails[i];
+                  final sender = e.from.isNotEmpty
+                      ? (e.from.first.name ?? e.from.first.email)
+                      : '(unknown)';
+                  return ListTile(
+                    leading: 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.preview ?? e.subject ?? '(no subject)',
+                      maxLines: 2,
+                      overflow: TextOverflow.ellipsis,
+                    ),
+                    trailing: Text(
+                      e.sentAt != null ? _dateFmt.format(e.sentAt!) : '',
+                      style: Theme.of(ctx).textTheme.bodySmall,
+                    ),
+                    onTap: () => context.push(
+                      '/accounts/$accountId/mailboxes/${Uri.encodeComponent(mailboxPath)}/emails/${Uri.encodeComponent(e.id)}',
+                    ),
+                  );
+                },
+              );
+            },
+          );
+        },
+      ),
+    );
+  }
+}
diff --git a/test/integration/account_sync_manager_test.dart b/test/integration/account_sync_manager_test.dart
index f3ac4e9..caad9d4 100644
--- a/test/integration/account_sync_manager_test.dart
+++ b/test/integration/account_sync_manager_test.dart
@@ -67,6 +67,10 @@ class _FakeEmails implements EmailRepository {
   @override
   Stream<List<Email>> observeEmails(String a, String m) => Stream.value([]);
 
+  @override
+  Stream<List<EmailThread>> observeThreads(String a, String m) =>
+      Stream.value([]);
+
   @override
   Future<Email?> getEmail(String id) async => null;
 
diff --git a/test/unit/account_sync_manager_test.dart b/test/unit/account_sync_manager_test.dart
index a3c17a0..8c35fcd 100644
--- a/test/unit/account_sync_manager_test.dart
+++ b/test/unit/account_sync_manager_test.dart
@@ -72,6 +72,13 @@ class FakeEmailRepository implements EmailRepository {
   Stream<List<Email>> observeEmails(String accountId, String mailboxPath) =>
       Stream.value([]);
 
+  @override
+  Stream<List<EmailThread>> observeThreads(
+    String accountId,
+    String mailboxPath,
+  ) =>
+      Stream.value([]);
+
   @override
   Future<Email?> getEmail(String emailId) async => null;
 
diff --git a/test/widget/helpers.dart b/test/widget/helpers.dart
index 39dd419..6ee3489 100644
--- a/test/widget/helpers.dart
+++ b/test/widget/helpers.dart
@@ -154,6 +154,29 @@ class FakeEmailRepository implements EmailRepository {
   Stream<List<Email>> observeEmails(String accountId, String mailboxPath) =>
       Stream.value(List.of(_emails));
 
+  @override
+  Stream<List<EmailThread>> observeThreads(
+    String accountId,
+    String mailboxPath,
+  ) =>
+      observeEmails(accountId, mailboxPath).map((emails) {
+        return emails.map((e) {
+          return EmailThread(
+            threadId: e.threadId ?? e.id,
+            subject: e.subject,
+            participants: e.from,
+            latestDate: e.sentAt ?? e.receivedAt,
+            messageCount: 1,
+            hasUnread: !e.isSeen,
+            isFlagged: e.isFlagged,
+            latestEmailId: e.id,
+            emailIds: [e.id],
+            accountId: e.accountId,
+            mailboxPath: e.mailboxPath,
+          );
+        }).toList();
+      });
+
   @override
   Future<Email?> getEmail(String emailId) async => _emailDetail;