- UI display: display_name first

- Fallback: name
  - Technical identity: still name

  ### What changed

  - Added account display helpers and display_name state in user model:
      - flutter/lib/models/user_model.dart:16
  - Account/logout label now uses display_name (@name) when both exist:
      - flutter/lib/mobile/pages/settings_page.dart:689
      - flutter/lib/desktop/pages/desktop_setting_page.dart:2016
      - flutter/lib/desktop/pages/desktop_setting_page.dart:2135
  - Desktop Account info now shows both when applicable:
      - Display Name: ...
      - Username: ...
      - flutter/lib/desktop/pages/desktop_setting_page.dart:2039
  - Previously done group-list behavior remains:
      - group user list displays display_name with name fallback
      - flutter/lib/common/widgets/my_group.dart:187
  - Persistence path for display_name remains enabled (including group cache/submodule field):
      - libs/hbb_common/src/config.rs:2347
  - src/client.rs:2630
  - LoginRequest.my_name now resolves as:
      1. OPTION_DISPLAY_NAME (manual override)
      2. user_info.display_name
      3. user_info.name
      4. OS username fallback

flutter/lib/common/hbbs/hbbs.dart

@@ -25,6 +25,7 @@ enum UserStatus { kDisabled, kNormal, kUnverified }
 // Is all the fields of the user needed?
 class UserPayload {
   String name = '';
+  String displayName = '';
   String email = '';
   String note = '';
   String? verifier;
@@ -33,6 +34,7 @@ class UserPayload {
 
   UserPayload.fromJson(Map<String, dynamic> json)
       : name = json['name'] ?? '',
+        displayName = json['display_name'] ?? '',
         email = json['email'] ?? '',
         note = json['note'] ?? '',
         verifier = json['verifier'],
@@ -46,6 +48,7 @@ class UserPayload {
   Map<String, dynamic> toJson() {
     final Map<String, dynamic> map = {
       'name': name,
+      'display_name': displayName,
       'status': status == UserStatus.kDisabled
           ? 0
           : status == UserStatus.kUnverified
@@ -58,9 +61,14 @@ class UserPayload {
   Map<String, dynamic> toGroupCacheJson() {
     final Map<String, dynamic> map = {
       'name': name,
+      'display_name': displayName,
     };
     return map;
   }
+
+  String get displayNameOrName {
+    return displayName.trim().isEmpty ? name : displayName;
+  }
 }
 
 class PeerPayload {

flutter/lib/common/widgets/my_group.dart

@@ -158,9 +158,9 @@ class _MyGroupState extends State<MyGroup> {
     return Obx(() {
       final userItems = gFFI.groupModel.users.where((p0) {
         if (searchAccessibleItemNameText.isNotEmpty) {
-          return p0.name
-              .toLowerCase()
-              .contains(searchAccessibleItemNameText.value.toLowerCase());
+          final search = searchAccessibleItemNameText.value.toLowerCase();
+          return p0.name.toLowerCase().contains(search) ||
+              p0.displayNameOrName.toLowerCase().contains(search);
         }
         return true;
       }).toList();
@@ -187,6 +187,7 @@ class _MyGroupState extends State<MyGroup> {
 
   Widget _buildUserItem(UserPayload user) {
     final username = user.name;
+    final displayName = user.displayNameOrName;
     return InkWell(onTap: () {
       isSelectedDeviceGroup.value = false;
       if (selectedAccessibleItemName.value != username) {
@@ -229,7 +230,7 @@ class _MyGroupState extends State<MyGroup> {
                     ),
                   ),
                 ).marginOnly(right: 4),
-                if (isMe) Flexible(child: Text(username)),
+                if (isMe) Flexible(child: Text(displayName)),
                 if (isMe)
                   Flexible(
                     child: Container(
@@ -246,7 +247,7 @@ class _MyGroupState extends State<MyGroup> {
                       ),
                     ),
                   ),
-                if (!isMe) Expanded(child: Text(username)),
+                if (!isMe) Expanded(child: Text(displayName)),
               ],
             ).paddingSymmetric(vertical: 4),
           ),

flutter/lib/desktop/pages/desktop_setting_page.dart

@@ -2016,7 +2016,9 @@ class _AccountState extends State<_Account> {
 
   Widget accountAction() {
     return Obx(() => _Button(
-        gFFI.userModel.userName.value.isEmpty ? 'Login' : 'Logout',
+        gFFI.userModel.userName.value.isEmpty
+            ? 'Login'
+            : 'Logout (${gFFI.userModel.accountLabelWithHandle})',
         () => {
               gFFI.userModel.userName.value.isEmpty
                   ? loginDialog()
@@ -2037,6 +2039,9 @@ class _AccountState extends State<_Account> {
           offstage: gFFI.userModel.userName.value.isEmpty,
           child: Column(
             children: [
+              if (gFFI.userModel.displayName.value.trim().isNotEmpty &&
+                  gFFI.userModel.displayName.value != gFFI.userModel.userName.value)
+                text('Display Name', gFFI.userModel.displayName.value),
               text('Username', gFFI.userModel.userName.value),
               // text('Group', gFFI.groupModel.groupName.value),
             ],
@@ -2130,7 +2135,9 @@ class _PluginState extends State<_Plugin> {
 
   Widget accountAction() {
     return Obx(() => _Button(
-        gFFI.userModel.userName.value.isEmpty ? 'Login' : 'Logout',
+        gFFI.userModel.userName.value.isEmpty
+            ? 'Login'
+            : 'Logout (${gFFI.userModel.accountLabelWithHandle})',
         () => {
               gFFI.userModel.userName.value.isEmpty
                   ? loginDialog()

flutter/lib/mobile/pages/settings_page.dart

@@ -688,7 +688,7 @@ class _SettingsState extends State<SettingsPage> with WidgetsBindingObserver {
               SettingsTile(
                 title: Obx(() => Text(gFFI.userModel.userName.value.isEmpty
                     ? translate('Login')
-                    : '${translate('Logout')} (${gFFI.userModel.userName.value})')),
+                    : '${translate('Logout')} (${gFFI.userModel.accountLabelWithHandle})')),
                 leading: Icon(Icons.person),
                 onPressed: (context) {
                   if (gFFI.userModel.userName.value.isEmpty) {

flutter/lib/models/user_model.dart

@@ -16,9 +16,23 @@ bool refreshingUser = false;
 
 class UserModel {
   final RxString userName = ''.obs;
+  final RxString displayName = ''.obs;
   final RxBool isAdmin = false.obs;
   final RxString networkError = ''.obs;
   bool get isLogin => userName.isNotEmpty;
+  String get displayNameOrUserName =>
+      displayName.value.trim().isEmpty ? userName.value : displayName.value;
+  String get accountLabelWithHandle {
+    final username = userName.value.trim();
+    if (username.isEmpty) {
+      return '';
+    }
+    final preferred = displayName.value.trim();
+    if (preferred.isEmpty || preferred == username) {
+      return username;
+    }
+    return '$preferred (@$username)';
+  }
   WeakReference<FFI> parent;
 
   UserModel(this.parent) {
@@ -98,7 +112,8 @@ class UserModel {
   _updateLocalUserInfo() {
     final userInfo = getLocalUserInfo();
     if (userInfo != null) {
-      userName.value = userInfo['name'];
+      userName.value = (userInfo['name'] ?? '').toString();
+      displayName.value = (userInfo['display_name'] ?? '').toString();
     }
   }
 
@@ -110,10 +125,12 @@ class UserModel {
       await gFFI.groupModel.reset();
     }
     userName.value = '';
+    displayName.value = '';
   }
 
   _parseAndUpdateUser(UserPayload user) {
     userName.value = user.name;
+    displayName.value = user.displayName;
     isAdmin.value = user.isAdmin;
     bind.mainSetLocalOption(key: 'user_info', value: jsonEncode(user));
     if (isWeb) {