diff --git a/Content.Client/_Sunrise/CartridgeLoader/Cartridges/MessagePanel.xaml.cs b/Content.Client/_Sunrise/CartridgeLoader/Cartridges/MessagePanel.xaml.cs
index 7eadbe4839..590afa7603 100644
--- a/Content.Client/_Sunrise/CartridgeLoader/Cartridges/MessagePanel.xaml.cs
+++ b/Content.Client/_Sunrise/CartridgeLoader/Cartridges/MessagePanel.xaml.cs
@@ -1,5 +1,6 @@
 using Content.Client._Sunrise.Messenger;
 using Content.Client.Resources;
+using Content.Client.Stylesheets;
 using Content.Shared._Sunrise.Messenger;
 using Robust.Client.AutoGenerated;
 using Robust.Client.GameObjects;
@@ -21,6 +22,11 @@ public sealed partial class MessagePanel : PanelContainer
     private ClientEmojiSystem? EmojiSystem => _entitySystemManager.GetEntitySystemOrNull<ClientEmojiSystem>();
     private SpriteSystem GetSpriteSystem() => _entitySystemManager.GetEntitySystem<SpriteSystem>();
 
+    /// <summary>
+    /// ID сообщения для идентификации при обновлении
+    /// </summary>
+    public long MessageId { get; private set; }
+
     private static readonly Type[] MessageTagsAllowed =
     [
         typeof(BoldItalicTag),
@@ -38,14 +44,38 @@ public sealed partial class MessagePanel : PanelContainer
         RobustXamlLoader.Load(this);
     }
 
+    public event Action<long>? OnDeleteMessage;
+    private Button? _deleteButton;
+
     public void UpdateMessage(MessengerMessage message, bool isOwnMessage, bool isPersonalChat, string? currentUserId)
     {
+        MessageId = message.MessageId;
         SenderLabel.Text = message.SenderName;
         TimeLabel.Text = message.Timestamp.ToString(@"hh\:mm");
 
         var parsedContent = EmojiSystem?.ParseEmojis(message.Content) ?? message.Content;
         ContentLabel.SetMessage(FormattedMessage.FromMarkupPermissive(parsedContent), MessageTagsAllowed);
 
+        if (isOwnMessage && _deleteButton == null)
+        {
+            _deleteButton = new Button
+            {
+                Text = "✖",
+                SetWidth = 24,
+                SetHeight = 24,
+                ToolTip = Loc.GetString("messenger-delete-message"),
+                Margin = new Thickness(2, 0)
+            };
+            _deleteButton.AddStyleClass(StyleClass.ButtonSmall);
+            _deleteButton.OnPressed += _ => OnDeleteMessage?.Invoke(MessageId);
+            RightContainer.AddChild(_deleteButton);
+        }
+        else if (!isOwnMessage && _deleteButton != null)
+        {
+            RightContainer.RemoveChild(_deleteButton);
+            _deleteButton = null;
+        }
+
         var roundedButtonTex = _resourceCache.GetTexture("/Textures/Interface/Nano/rounded_button_bordered.svg.96dpi.png");
         var roundedStyleBox = new StyleBoxTexture
         {
diff --git a/Content.Client/_Sunrise/CartridgeLoader/Cartridges/MessengerUi.cs b/Content.Client/_Sunrise/CartridgeLoader/Cartridges/MessengerUi.cs
index 0867950af0..0db7b11624 100644
--- a/Content.Client/_Sunrise/CartridgeLoader/Cartridges/MessengerUi.cs
+++ b/Content.Client/_Sunrise/CartridgeLoader/Cartridges/MessengerUi.cs
@@ -29,6 +29,14 @@ public sealed partial class MessengerUi : UIFragment
             SendMessengerMessage(MessengerUiAction.RequestMessages, userInterface, chatId: chatId);
         _fragment.OnToggleMute += (chatId, isMuted) =>
             SendMessengerMessage(MessengerUiAction.ToggleMute, userInterface, chatId: chatId, isMuted: isMuted);
+        _fragment.OnAcceptInvite += (groupId) =>
+            SendMessengerMessage(MessengerUiAction.AcceptInvite, userInterface, groupId: groupId);
+        _fragment.OnDeclineInvite += (groupId) =>
+            SendMessengerMessage(MessengerUiAction.DeclineInvite, userInterface, groupId: groupId);
+        _fragment.OnLeaveGroup += (groupId) =>
+            SendMessengerMessage(MessengerUiAction.LeaveGroup, userInterface, groupId: groupId);
+        _fragment.OnDeleteMessage += (chatId, messageId) =>
+            SendMessengerMessage(MessengerUiAction.DeleteMessage, userInterface, chatId: chatId, messageId: messageId);
     }
 
     public override void UpdateState(BoundUserInterfaceState state)
@@ -48,9 +56,10 @@ public sealed partial class MessengerUi : UIFragment
         string? groupName = null,
         string? userId = null,
         string? chatId = null,
-        bool? isMuted = null)
+        bool? isMuted = null,
+        long? messageId = null)
     {
-        var messengerMessage = new MessengerUiMessageEvent(action, recipientId, groupId, content, groupName, userId, chatId, isMuted);
+        var messengerMessage = new MessengerUiMessageEvent(action, recipientId, groupId, content, groupName, userId, chatId, isMuted, messageId);
         var message = new CartridgeUiMessage(messengerMessage);
         userInterface.SendMessage(message);
     }
diff --git a/Content.Client/_Sunrise/CartridgeLoader/Cartridges/MessengerUiFragment.xaml b/Content.Client/_Sunrise/CartridgeLoader/Cartridges/MessengerUiFragment.xaml
index 4c85109c3d..e6d9920aee 100644
--- a/Content.Client/_Sunrise/CartridgeLoader/Cartridges/MessengerUiFragment.xaml
+++ b/Content.Client/_Sunrise/CartridgeLoader/Cartridges/MessengerUiFragment.xaml
@@ -9,7 +9,7 @@
         VerticalExpand="True">
         <BoxContainer
             Orientation="Vertical"
-            SetWidth="200"
+            SetWidth="220"
             VerticalExpand="True">
             <BoxContainer
                 HorizontalExpand="True"
@@ -30,16 +30,27 @@
                 PlaceHolder="{Loc 'messenger-search-placeholder'}" />
             <BoxContainer
                 HorizontalExpand="True"
-                Orientation="Horizontal"
+                Orientation="Vertical"
                 Margin="4,2">
-                <Button
-                    Name="PersonalChatsTab"
-                    Text="{Loc 'messenger-tab-personal'}"
+                <BoxContainer
                     HorizontalExpand="True"
-                    ToggleMode="True" />
+                    Orientation="Horizontal">
+                    <Button
+                        Name="PersonalChatsTab"
+                        Text="{Loc 'messenger-tab-personal'}"
+                        HorizontalExpand="True"
+                        SizeFlagsStretchRatio="1"
+                        ToggleMode="True" />
+                    <Button
+                        Name="GroupChatsTab"
+                        Text="{Loc 'messenger-tab-groups'}"
+                        HorizontalExpand="True"
+                        SizeFlagsStretchRatio="1"
+                        ToggleMode="True" />
+                </BoxContainer>
                 <Button
-                    Name="GroupChatsTab"
-                    Text="{Loc 'messenger-tab-groups'}"
+                    Name="InvitesTab"
+                    Text="{Loc 'messenger-tab-invites'}"
                     HorizontalExpand="True"
                     ToggleMode="True" />
             </BoxContainer>
diff --git a/Content.Client/_Sunrise/CartridgeLoader/Cartridges/MessengerUiFragment.xaml.cs b/Content.Client/_Sunrise/CartridgeLoader/Cartridges/MessengerUiFragment.xaml.cs
index f3b2d8d7ba..c40e361a70 100644
--- a/Content.Client/_Sunrise/CartridgeLoader/Cartridges/MessengerUiFragment.xaml.cs
+++ b/Content.Client/_Sunrise/CartridgeLoader/Cartridges/MessengerUiFragment.xaml.cs
@@ -29,6 +29,10 @@ public sealed partial class MessengerUiFragment : BoxContainer
     public event Action<string, string>? OnRemoveFromGroup;
     public event Action<string>? OnRequestMessages;
     public event Action<string, bool>? OnToggleMute;
+    public event Action<string>? OnAcceptInvite;
+    public event Action<string>? OnDeclineInvite;
+    public event Action<string>? OnLeaveGroup;
+    public event Action<string, long>? OnDeleteMessage;
 
     private string? _currentChatId;
     private MessengerUiState? _currentState;
@@ -40,6 +44,11 @@ public sealed partial class MessengerUiFragment : BoxContainer
     private int _lastMessageCount;
     private bool _isScrolledToBottom = true;
 
+    /// <summary>
+    /// Максимальное количество сообщений, отображаемых в UI (для оптимизации производительности)
+    /// </summary>
+    private const int MaxDisplayedMessages = 100;
+
     private Dictionary<string, int>? _lastUnreadCounts;
     private HashSet<string>? _lastUserIds;
     private HashSet<string>? _lastGroupIds;
@@ -88,6 +97,7 @@ public sealed partial class MessengerUiFragment : BoxContainer
         SearchInput.OnTextChanged += OnSearchTextChanged;
         PersonalChatsTab.OnPressed += _ => SwitchTab(0);
         GroupChatsTab.OnPressed += _ => SwitchTab(1);
+        InvitesTab.OnPressed += _ => SwitchTab(2);
         MuteCheckBox.OnToggled += OnMuteToggled;
 
         PersonalChatsTab.Pressed = true;
@@ -207,6 +217,11 @@ public sealed partial class MessengerUiFragment : BoxContainer
                 .ThenBy(m => m.Content)
                 .ToList();
 
+            if (messages.Count > MaxDisplayedMessages)
+            {
+                messages = messages.Skip(messages.Count - MaxDisplayedMessages).ToList();
+            }
+
             var wasChatChanged = savedChatId != _currentChatId;
 
             if (wasChatChanged)
@@ -288,6 +303,7 @@ public sealed partial class MessengerUiFragment : BoxContainer
         }
 
         UpdateChatsList(state);
+        UpdateTabButtons(state);
 
         if (_showMembersList && _currentGroupId != null)
         {
@@ -295,15 +311,158 @@ public sealed partial class MessengerUiFragment : BoxContainer
         }
     }
 
+    private void UpdateTabButtons(MessengerUiState state)
+    {
+        int personalUnreadChats = 0;
+        int groupsUnreadChats = 0;
+        int invitesCount = 0;
+
+        if (state.CurrentUserId != null)
+        {
+            foreach (var user in state.Users)
+            {
+                if (user.UserId == state.CurrentUserId)
+                    continue;
+
+                var chatId = GetPersonalChatId(user.UserId);
+                if (state.UnreadCounts.TryGetValue(chatId, out var count) && count > 0)
+                {
+                    personalUnreadChats++;
+                }
+            }
+        }
+
+        foreach (var group in state.Groups)
+        {
+            if (state.UnreadCounts.TryGetValue(group.GroupId, out var count) && count > 0)
+            {
+                groupsUnreadChats++;
+            }
+        }
+
+        if (state.ActiveInvites != null)
+        {
+            invitesCount = state.ActiveInvites.Count;
+        }
+
+        UpdateTabButton(PersonalChatsTab, personalUnreadChats);
+        UpdateTabButton(GroupChatsTab, groupsUnreadChats);
+        UpdateTabButton(InvitesTab, invitesCount);
+    }
+
+    private void UpdateTabButton(Button button, int count)
+    {
+        BoxContainer? textContainer;
+        Label? nameLabel;
+        var isInvitesTab = button == InvitesTab;
+
+        if (button.ChildCount == 0)
+        {
+            textContainer = new BoxContainer
+            {
+                Orientation = LayoutOrientation.Horizontal,
+                HorizontalExpand = true
+            };
+            nameLabel = new Label
+            {
+                Text = button.Text ?? "",
+                HorizontalExpand = false,
+                Align = isInvitesTab ? Label.AlignMode.Center : Label.AlignMode.Left
+            };
+            textContainer.AddChild(nameLabel);
+            button.AddChild(textContainer);
+        }
+        else
+        {
+            textContainer = button.Children.FirstOrDefault() as BoxContainer;
+            if (textContainer == null)
+            {
+                textContainer = new BoxContainer
+                {
+                    Orientation = LayoutOrientation.Horizontal,
+                    HorizontalExpand = true
+                };
+                nameLabel = new Label
+                {
+                    Text = button.Text ?? "",
+                    HorizontalExpand = false,
+                    Align = isInvitesTab ? Label.AlignMode.Center : Label.AlignMode.Left
+                };
+                textContainer.AddChild(nameLabel);
+                button.RemoveAllChildren();
+                button.AddChild(textContainer);
+            }
+            else
+            {
+                nameLabel = textContainer.Children.OfType<Label>().FirstOrDefault(l => !l.StyleClasses.Contains("Bold"));
+                if (nameLabel == null)
+                {
+                    nameLabel = new Label
+                    {
+                        Text = button.Text ?? "",
+                        HorizontalExpand = false,
+                        Align = isInvitesTab ? Label.AlignMode.Center : Label.AlignMode.Left
+                    };
+                    textContainer.AddChild(nameLabel);
+                }
+                else
+                {
+                    nameLabel.HorizontalExpand = false;
+                    nameLabel.Align = isInvitesTab ? Label.AlignMode.Center : Label.AlignMode.Left;
+                }
+            }
+        }
+
+        if (textContainer == null || nameLabel == null)
+            return;
+
+        var existingCounter = textContainer.Children.OfType<Label>()
+            .FirstOrDefault(l => l != nameLabel && l.StyleClasses.Contains("Bold"));
+
+        if (count > 0)
+        {
+            button.ModulateSelfOverride = Color.Red;
+
+            if (existingCounter == null)
+            {
+                var counterLabel = new Label
+                {
+                    Text = $"({count})",
+                    Align = Label.AlignMode.Left,
+                    StyleClasses = { "Bold" },
+                    HorizontalExpand = false
+                };
+                counterLabel.ModulateSelfOverride = Color.White;
+                textContainer.AddChild(counterLabel);
+            }
+            else
+            {
+                existingCounter.Text = $"({count})";
+            }
+        }
+        else
+        {
+            button.ModulateSelfOverride = null;
+
+            if (existingCounter != null)
+            {
+                textContainer.RemoveChild(existingCounter);
+            }
+        }
+    }
+
+
     private void SwitchTab(int tabIndex)
     {
         _activeTab = tabIndex;
         PersonalChatsTab.Pressed = tabIndex == 0;
         GroupChatsTab.Pressed = tabIndex == 1;
+        InvitesTab.Pressed = tabIndex == 2;
         CreateGroupButton.Visible = tabIndex == 1;
         if (_currentState != null)
         {
             UpdateChatsList(_currentState);
+            UpdateTabButtons(_currentState);
         }
     }
 
@@ -444,7 +603,7 @@ public sealed partial class MessengerUiFragment : BoxContainer
                 ChatsContainer.AddChild(buttonContainer);
             }
         }
-        else
+        else if (_activeTab == 1)
         {
             foreach (var group in state.Groups)
             {
@@ -510,6 +669,94 @@ public sealed partial class MessengerUiFragment : BoxContainer
                 ChatsContainer.AddChild(groupContainer);
             }
         }
+        else if (_activeTab == 2)
+        {
+            if (state.ActiveInvites.Count > 0)
+            {
+                foreach (var invite in state.ActiveInvites)
+                {
+                    var invitePanel = new PanelContainer
+                    {
+                        HorizontalExpand = true,
+                        Margin = new Thickness(2, 2)
+                    };
+                    invitePanel.PanelOverride = new StyleBoxFlat
+                    {
+                        BackgroundColor = Color.FromHex("#25252A"),
+                        BorderColor = Color.FromHex("#3D4059"),
+                        BorderThickness = new Thickness(1),
+                        ContentMarginLeftOverride = 6,
+                        ContentMarginRightOverride = 6,
+                        ContentMarginTopOverride = 4,
+                        ContentMarginBottomOverride = 4
+                    };
+
+                    var inviteContainer = new BoxContainer
+                    {
+                        Orientation = LayoutOrientation.Vertical,
+                        HorizontalExpand = true
+                    };
+
+                    var groupNameLabel = new Label
+                    {
+                        Text = invite.GroupName,
+                        StyleClasses = { "Bold" },
+                        HorizontalExpand = true,
+                        Margin = new Thickness(0, 0, 0, 4),
+                        ClipText = true
+                    };
+                    inviteContainer.AddChild(groupNameLabel);
+
+                    var inviteInfo = new RichTextLabel
+                    {
+                        HorizontalExpand = true,
+                        Margin = new Thickness(0, 0, 0, 8)
+                    };
+                    inviteInfo.SetMessage(Loc.GetString("messenger-invite-info", ("inviter", invite.InviterName)), tagsAllowed: null);
+                    inviteInfo.StyleClasses.Add("LabelSubText");
+                    inviteContainer.AddChild(inviteInfo);
+
+                    var buttonsContainer = new BoxContainer
+                    {
+                        Orientation = LayoutOrientation.Horizontal,
+                        HorizontalExpand = true
+                    };
+
+                    var acceptButton = new Button
+                    {
+                        Text = "✓",
+                        HorizontalExpand = true,
+                        Margin = new Thickness(2, 0)
+                    };
+                    acceptButton.OnPressed += _ => OnAcceptInvite?.Invoke(invite.GroupId);
+                    buttonsContainer.AddChild(acceptButton);
+
+                    var declineButton = new Button
+                    {
+                        Text = "✖",
+                        HorizontalExpand = true,
+                        Margin = new Thickness(2, 0)
+                    };
+                    declineButton.OnPressed += _ => OnDeclineInvite?.Invoke(invite.GroupId);
+                    buttonsContainer.AddChild(declineButton);
+
+                    inviteContainer.AddChild(buttonsContainer);
+                    invitePanel.AddChild(inviteContainer);
+                    ChatsContainer.AddChild(invitePanel);
+                }
+            }
+            else
+            {
+                var noInvitesLabel = new Label
+                {
+                    Text = Loc.GetString("messenger-no-invites"),
+                    HorizontalExpand = true,
+                    HorizontalAlignment = HAlignment.Center,
+                    Margin = new Thickness(4)
+                };
+                ChatsContainer.AddChild(noInvitesLabel);
+            }
+        }
     }
 
     private bool AreUnreadCountsEqual(Dictionary<string, int> counts1, Dictionary<string, int> counts2)
@@ -789,31 +1036,86 @@ public sealed partial class MessengerUiFragment : BoxContainer
             MembersList.AddChild(noMembersLabel);
         }
 
-        if (isUserGroup && isOwner && _currentState != null && _currentState.ServerAvailable && _currentState.IsRegistered)
+        if (isUserGroup && _currentState != null && _currentState.ServerAvailable && _currentState.IsRegistered)
         {
-            AddMemberButton.Disabled = false;
-            AddMemberButton.Visible = true;
-            AddMemberButton.OnPressed -= OnAddMemberButtonPressed;
-            AddMemberButton.OnPressed += OnAddMemberButtonPressed;
+            var buttonsContainer = new BoxContainer
+            {
+                Orientation = LayoutOrientation.Horizontal,
+                HorizontalExpand = true,
+                Margin = new Thickness(2, 4)
+            };
+
+            if (group.Type == MessengerGroupType.UserCreated && isOwner)
+            {
+                if (AddMemberButton.Parent != null)
+                {
+                    AddMemberButton.Parent.RemoveChild(AddMemberButton);
+                }
+                AddMemberButton.Disabled = false;
+                AddMemberButton.Visible = true;
+                AddMemberButton.Text = Loc.GetString("messenger-invite-member-button");
+                AddMemberButton.HorizontalExpand = true;
+                AddMemberButton.Margin = new Thickness(2, 0);
+                AddMemberButton.OnPressed -= OnAddMemberButtonPressed;
+                AddMemberButton.OnPressed += OnAddMemberButtonPressed;
+                buttonsContainer.AddChild(AddMemberButton);
+            }
+            else
+            {
+                AddMemberButton.Disabled = true;
+                AddMemberButton.Visible = false;
+            }
+
+            var leaveButton = new Button
+            {
+                Text = Loc.GetString("messenger-leave-group"),
+                HorizontalExpand = true,
+                Margin = new Thickness(2, 0)
+            };
+            leaveButton.OnPressed += _ =>
+            {
+                if (_currentGroupId != null)
+                {
+                    OnLeaveGroup?.Invoke(_currentGroupId);
+                }
+            };
+            buttonsContainer.AddChild(leaveButton);
+
+            MembersList.AddChild(buttonsContainer);
         }
         else
         {
             AddMemberButton.Disabled = true;
             AddMemberButton.Visible = false;
         }
+
     }
 
     private void UpdateMessages(List<MessengerMessage> messages)
     {
+        if (messages.Count > MaxDisplayedMessages)
+        {
+            messages = messages.Skip(messages.Count - MaxDisplayedMessages).ToList();
+        }
+
         var hasNewMessages = messages.Count > _lastMessageCount;
 
         UpdateScrollBottomState();
         var wasAtBottom = _isScrolledToBottom;
 
-
-        if (_lastMessageCount == 0)
+        if (_lastMessageCount == 0 || messages.Count < _lastMessageCount)
         {
             MessagesList.RemoveAllChildren();
+            _lastMessageCount = 0;
+        }
+        else if (messages.Count > 0 && _lastMessageCount > 0)
+        {
+            var firstDisplayedId = GetFirstDisplayedMessageId();
+            if (firstDisplayedId.HasValue && messages[0].MessageId != firstDisplayedId.Value)
+            {
+                MessagesList.RemoveAllChildren();
+                _lastMessageCount = 0;
+            }
         }
 
         var hasStatusChange = false;
@@ -858,17 +1160,53 @@ public sealed partial class MessengerUiFragment : BoxContainer
             _lastMessageCount = 0;
         }
 
+        var existingMessageIds = new HashSet<long>();
+        foreach (var child in MessagesList.Children)
+        {
+            if (child is MessagePanel panel)
+            {
+                existingMessageIds.Add(panel.MessageId);
+            }
+        }
+
         for (int i = _lastMessageCount; i < messages.Count; i++)
         {
             var message = messages[i];
+            if (existingMessageIds.Contains(message.MessageId))
+                continue;
+
             var isOwnMessage = _currentState?.CurrentUserId == message.SenderId;
             var isPersonalChat = _currentChatId != null && _currentChatId.StartsWith("personal_");
 
             var messagePanel = new MessagePanel();
             messagePanel.UpdateMessage(message, isOwnMessage, isPersonalChat, _currentState?.CurrentUserId);
+            if (isOwnMessage)
+            {
+                messagePanel.OnDeleteMessage += (messageId) =>
+                {
+                    if (_currentChatId != null)
+                    {
+                        OnDeleteMessage?.Invoke(_currentChatId, messageId);
+                    }
+                };
+            }
             MessagesList.AddChild(messagePanel);
         }
 
+        var messageIds = new HashSet<long>(messages.Select(m => m.MessageId));
+        var toRemove = new List<Control>();
+        foreach (var child in MessagesList.Children)
+        {
+            if (child is MessagePanel panel && !messageIds.Contains(panel.MessageId))
+            {
+                toRemove.Add(child);
+            }
+        }
+        foreach (var child in toRemove)
+        {
+            MessagesList.RemoveChild(child);
+        }
+
         var previousMessageCount = _lastMessageCount;
         _lastMessageCount = messages.Count;
 
@@ -895,6 +1233,21 @@ public sealed partial class MessengerUiFragment : BoxContainer
             UpdateScrollBottomState();
     }
 
+    /// <summary>
+    /// Получает ID первого отображаемого сообщения для проверки необходимости полной перерисовки
+    /// </summary>
+    private long? GetFirstDisplayedMessageId()
+    {
+        if (MessagesList.ChildCount == 0)
+            return null;
+
+        var firstChild = MessagesList.Children.FirstOrDefault();
+        if (firstChild is not MessagePanel firstPanel)
+            return null;
+
+        return firstPanel.MessageId;
+    }
+
     private void SendMessage()
     {
         var messageText = MessageInput.Text;
@@ -1023,7 +1376,8 @@ public sealed partial class MessengerUiFragment : BoxContainer
         }
 
         var dialog = new AddUserDialog();
-        dialog.SetTitle(Loc.GetString("messenger-add-user-to-group-title", ("groupName", groupName)));
+        var dialogTitle = Loc.GetString("messenger-invite-user-to-group-title", ("groupName", groupName));
+        dialog.SetTitle(dialogTitle);
         _addUserDialog = dialog;
 
         dialog.SetAvailableUsers(availableUsers);
diff --git a/Content.Server/_Sunrise/CartridgeLoader/Cartridges/MessengerCartridgeComponent.cs b/Content.Server/_Sunrise/CartridgeLoader/Cartridges/MessengerCartridgeComponent.cs
index ef8ea72809..9c2b4a626a 100644
--- a/Content.Server/_Sunrise/CartridgeLoader/Cartridges/MessengerCartridgeComponent.cs
+++ b/Content.Server/_Sunrise/CartridgeLoader/Cartridges/MessengerCartridgeComponent.cs
@@ -97,4 +97,10 @@ public sealed partial class MessengerCartridgeComponent : Component
     /// </summary>
     [ViewVariables]
     public Dictionary<string, int> ServerUnreadCounts = new();
+
+    /// <summary>
+    /// Активные приглашения в группы
+    /// </summary>
+    [ViewVariables]
+    public List<MessengerGroupInvite> ActiveInvites = new();
 }
diff --git a/Content.Server/_Sunrise/CartridgeLoader/Cartridges/MessengerCartridgeSystem.Messaging.cs b/Content.Server/_Sunrise/CartridgeLoader/Cartridges/MessengerCartridgeSystem.Messaging.cs
index 7c67b14277..a01975d1da 100644
--- a/Content.Server/_Sunrise/CartridgeLoader/Cartridges/MessengerCartridgeSystem.Messaging.cs
+++ b/Content.Server/_Sunrise/CartridgeLoader/Cartridges/MessengerCartridgeSystem.Messaging.cs
@@ -52,6 +52,22 @@ public sealed partial class MessengerCartridgeSystem
                 if (message.ChatId != null && message.IsMuted.HasValue)
                     ToggleMute(uid, component, message.ChatId, message.IsMuted.Value);
                 break;
+            case MessengerUiAction.AcceptInvite:
+                if (message.GroupId != null)
+                    AcceptInvite(uid, component, loaderUid, deviceNetwork, message.GroupId);
+                break;
+            case MessengerUiAction.DeclineInvite:
+                if (message.GroupId != null)
+                    DeclineInvite(uid, component, loaderUid, deviceNetwork, message.GroupId);
+                break;
+            case MessengerUiAction.LeaveGroup:
+                if (message.GroupId != null)
+                    LeaveGroup(uid, component, loaderUid, deviceNetwork, message.GroupId);
+                break;
+            case MessengerUiAction.DeleteMessage:
+                if (message.ChatId != null && message.MessageId.HasValue)
+                    DeleteMessage(uid, component, loaderUid, deviceNetwork, message.ChatId, message.MessageId.Value);
+                break;
         }
     }
 
@@ -307,4 +323,149 @@ public sealed partial class MessengerCartridgeSystem
         _deviceNetwork.QueuePacket(loaderUid, component.ServerAddress, payload, frequency: messengerFreq, network: pdaDevice.DeviceNetId);
         RestoreFrequency(loaderUid, pdaDevice, originalFreq);
     }
+
+    private void AcceptInvite(EntityUid uid, MessengerCartridgeComponent component, EntityUid loaderUid, DeviceNetworkComponent deviceNetwork, string groupId)
+    {
+        if (component.ServerAddress == null || !component.IsRegistered)
+            return;
+
+        var messengerFreq = GetMessengerFrequency();
+        if (!messengerFreq.HasValue)
+            return;
+
+        SetMessengerFrequency(loaderUid, deviceNetwork, out var originalFreq);
+
+        if (!TryComp<DeviceNetworkComponent>(loaderUid, out var pdaDevice))
+        {
+            RestoreFrequency(loaderUid, deviceNetwork, originalFreq);
+            return;
+        }
+
+        if (!_deviceNetwork.IsAddressPresent(pdaDevice.DeviceNetId, component.ServerAddress))
+        {
+            RestoreFrequency(loaderUid, pdaDevice, originalFreq);
+            return;
+        }
+
+        var payload = new NetworkPayload
+        {
+            [DeviceNetworkConstants.Command] = MessengerCommands.CmdAcceptInvite,
+            [MessengerCommands.CmdAcceptInvite] = new NetworkPayload
+            {
+                ["group_id"] = groupId
+            }
+        };
+
+        _deviceNetwork.QueuePacket(loaderUid, component.ServerAddress, payload, frequency: messengerFreq, network: pdaDevice.DeviceNetId);
+        RestoreFrequency(loaderUid, pdaDevice, originalFreq);
+    }
+
+    private void DeclineInvite(EntityUid uid, MessengerCartridgeComponent component, EntityUid loaderUid, DeviceNetworkComponent deviceNetwork, string groupId)
+    {
+        if (component.ServerAddress == null || !component.IsRegistered)
+            return;
+
+        var messengerFreq = GetMessengerFrequency();
+        if (!messengerFreq.HasValue)
+            return;
+
+        SetMessengerFrequency(loaderUid, deviceNetwork, out var originalFreq);
+
+        if (!TryComp<DeviceNetworkComponent>(loaderUid, out var pdaDevice))
+        {
+            RestoreFrequency(loaderUid, deviceNetwork, originalFreq);
+            return;
+        }
+
+        if (!_deviceNetwork.IsAddressPresent(pdaDevice.DeviceNetId, component.ServerAddress))
+        {
+            RestoreFrequency(loaderUid, pdaDevice, originalFreq);
+            return;
+        }
+
+        var payload = new NetworkPayload
+        {
+            [DeviceNetworkConstants.Command] = MessengerCommands.CmdDeclineInvite,
+            [MessengerCommands.CmdDeclineInvite] = new NetworkPayload
+            {
+                ["group_id"] = groupId
+            }
+        };
+
+        _deviceNetwork.QueuePacket(loaderUid, component.ServerAddress, payload, frequency: messengerFreq, network: pdaDevice.DeviceNetId);
+        RestoreFrequency(loaderUid, pdaDevice, originalFreq);
+    }
+
+    private void LeaveGroup(EntityUid uid, MessengerCartridgeComponent component, EntityUid loaderUid, DeviceNetworkComponent deviceNetwork, string groupId)
+    {
+        if (component.ServerAddress == null || !component.IsRegistered)
+            return;
+
+        var messengerFreq = GetMessengerFrequency();
+        if (!messengerFreq.HasValue)
+            return;
+
+        SetMessengerFrequency(loaderUid, deviceNetwork, out var originalFreq);
+
+        if (!TryComp<DeviceNetworkComponent>(loaderUid, out var pdaDevice))
+        {
+            RestoreFrequency(loaderUid, deviceNetwork, originalFreq);
+            return;
+        }
+
+        if (!_deviceNetwork.IsAddressPresent(pdaDevice.DeviceNetId, component.ServerAddress))
+        {
+            RestoreFrequency(loaderUid, pdaDevice, originalFreq);
+            return;
+        }
+
+        var payload = new NetworkPayload
+        {
+            [DeviceNetworkConstants.Command] = MessengerCommands.CmdLeaveGroup,
+            [MessengerCommands.CmdLeaveGroup] = new NetworkPayload
+            {
+                ["group_id"] = groupId
+            }
+        };
+
+        _deviceNetwork.QueuePacket(loaderUid, component.ServerAddress, payload, frequency: messengerFreq, network: pdaDevice.DeviceNetId);
+        RestoreFrequency(loaderUid, pdaDevice, originalFreq);
+    }
+
+    private void DeleteMessage(EntityUid uid, MessengerCartridgeComponent component, EntityUid loaderUid, DeviceNetworkComponent deviceNetwork, string chatId, long messageId)
+    {
+        if (component.ServerAddress == null || !component.IsRegistered)
+            return;
+
+        var messengerFreq = GetMessengerFrequency();
+        if (!messengerFreq.HasValue)
+            return;
+
+        SetMessengerFrequency(loaderUid, deviceNetwork, out var originalFreq);
+
+        if (!TryComp<DeviceNetworkComponent>(loaderUid, out var pdaDevice))
+        {
+            RestoreFrequency(loaderUid, deviceNetwork, originalFreq);
+            return;
+        }
+
+        if (!_deviceNetwork.IsAddressPresent(pdaDevice.DeviceNetId, component.ServerAddress))
+        {
+            RestoreFrequency(loaderUid, pdaDevice, originalFreq);
+            return;
+        }
+
+        var payload = new NetworkPayload
+        {
+            [DeviceNetworkConstants.Command] = MessengerCommands.CmdDeleteMessage,
+            [MessengerCommands.CmdDeleteMessage] = new NetworkPayload
+            {
+                ["message_id"] = messageId,
+                ["chat_id"] = chatId
+            }
+        };
+
+        _deviceNetwork.QueuePacket(loaderUid, component.ServerAddress, payload, frequency: messengerFreq, network: pdaDevice.DeviceNetId);
+        RestoreFrequency(loaderUid, pdaDevice, originalFreq);
+    }
 }
diff --git a/Content.Server/_Sunrise/CartridgeLoader/Cartridges/MessengerCartridgeSystem.PacketHandlers.cs b/Content.Server/_Sunrise/CartridgeLoader/Cartridges/MessengerCartridgeSystem.PacketHandlers.cs
index fcf1b26018..8144f54819 100644
--- a/Content.Server/_Sunrise/CartridgeLoader/Cartridges/MessengerCartridgeSystem.PacketHandlers.cs
+++ b/Content.Server/_Sunrise/CartridgeLoader/Cartridges/MessengerCartridgeSystem.PacketHandlers.cs
@@ -53,6 +53,21 @@ public sealed partial class MessengerCartridgeSystem
             case MessengerCommands.CmdUserAddedToGroup:
                 HandleUserAddedToGroup(uid, component, packet, loaderUid);
                 break;
+            case MessengerCommands.CmdInviteReceived:
+                HandleInviteReceived(uid, component, packet, loaderUid);
+                break;
+            case MessengerCommands.CmdInvitesList:
+                HandleInvitesList(uid, component, packet, loaderUid);
+                break;
+            case MessengerCommands.CmdUserLeftGroup:
+                HandleUserLeftGroup(uid, component, packet, loaderUid);
+                break;
+            case MessengerCommands.CmdGroupDeleted:
+                HandleGroupDeleted(uid, component, packet, loaderUid);
+                break;
+            case MessengerCommands.CmdMessageDeleted:
+                HandleMessageDeleted(uid, component, packet, loaderUid);
+                break;
             default:
                 Sawmill.Warning($"Unknown command received: {command}");
                 break;
@@ -181,6 +196,17 @@ public sealed partial class MessengerCartridgeSystem
 
         component.Groups = groups;
 
+        foreach (var group in groups)
+        {
+            if (group.Type == MessengerGroupType.Automatic && group.AutoGroupPrototypeId != null)
+            {
+                if (!component.MutedGroupChats.Contains(group.GroupId))
+                {
+                    component.MutedGroupChats.Add(group.GroupId);
+                }
+            }
+        }
+
         if (serverUnreadCounts != null)
         {
             foreach (var (chatId, count) in serverUnreadCounts)
@@ -494,6 +520,82 @@ public sealed partial class MessengerCartridgeSystem
         }
     }
 
+    private void HandleInviteReceived(EntityUid uid, MessengerCartridgeComponent component, DeviceNetworkPacketEvent packet, EntityUid loaderUid)
+    {
+        if (!packet.Data.TryGetValue("group_id", out object? groupIdObj) ||
+            !packet.Data.TryGetValue("group_name", out object? groupNameObj) ||
+            !packet.Data.TryGetValue("inviter_id", out object? inviterIdObj) ||
+            !packet.Data.TryGetValue("inviter_name", out object? inviterNameObj) ||
+            !packet.Data.TryGetValue("created_at", out object? createdAtObj))
+            return;
+
+        var groupId = groupIdObj?.ToString();
+        var groupName = groupNameObj?.ToString();
+        var inviterId = inviterIdObj?.ToString();
+        var inviterName = inviterNameObj?.ToString();
+
+        if (groupId == null || groupName == null || inviterId == null || inviterName == null)
+            return;
+
+        if (!double.TryParse(createdAtObj?.ToString(), out var createdAtSeconds))
+            return;
+
+        var createdAt = TimeSpan.FromSeconds(createdAtSeconds);
+
+        var invite = new MessengerGroupInvite(groupId, groupName, inviterId, inviterName, component.UserId ?? string.Empty, createdAt);
+
+        var isNewInvite = !component.ActiveInvites.Any(inv => inv.GroupId == groupId && inv.InviterId == inviterId);
+
+        if (isNewInvite)
+        {
+            component.ActiveInvites.Add(invite);
+
+            // Воспроизводим рингтон при получении нового инвайта
+            if (TryComp<RingerComponent>(loaderUid, out var ringer))
+            {
+                _ringer.RingerPlayRingtone(loaderUid);
+            }
+        }
+
+        UpdateUiState(uid, loaderUid, component);
+    }
+
+    private void HandleInvitesList(EntityUid uid, MessengerCartridgeComponent component, DeviceNetworkPacketEvent packet, EntityUid loaderUid)
+    {
+        if (!packet.Data.TryGetValue("invites", out List<Dictionary<string, object>>? invitesData))
+            return;
+
+        component.ActiveInvites.Clear();
+
+        foreach (var inviteData in invitesData)
+        {
+            if (!inviteData.TryGetValue("group_id", out object? groupIdObj) ||
+                !inviteData.TryGetValue("group_name", out object? groupNameObj) ||
+                !inviteData.TryGetValue("inviter_id", out object? inviterIdObj) ||
+                !inviteData.TryGetValue("inviter_name", out object? inviterNameObj) ||
+                !inviteData.TryGetValue("created_at", out object? createdAtObj))
+                continue;
+
+            var groupId = groupIdObj?.ToString();
+            var groupName = groupNameObj?.ToString();
+            var inviterId = inviterIdObj?.ToString();
+            var inviterName = inviterNameObj?.ToString();
+
+            if (groupId == null || groupName == null || inviterId == null || inviterName == null)
+                continue;
+
+            if (!double.TryParse(createdAtObj?.ToString(), out var createdAtSeconds))
+                continue;
+
+            var createdAt = TimeSpan.FromSeconds(createdAtSeconds);
+
+            var invite = new MessengerGroupInvite(groupId, groupName, inviterId, inviterName, component.UserId ?? string.Empty, createdAt);
+            component.ActiveInvites.Add(invite);
+        }
+
+        UpdateUiState(uid, loaderUid, component);
+    }
+
     private void HandleGroupCreated(EntityUid uid, MessengerCartridgeComponent component, DeviceNetworkPacketEvent packet, EntityUid loaderUid)
     {
         if (TryComp<DeviceNetworkComponent>(loaderUid, out var deviceNetwork))
@@ -520,4 +622,83 @@ public sealed partial class MessengerCartridgeSystem
         if (TryComp<DeviceNetworkComponent>(loaderUid, out var deviceNetwork))
             RequestGroups(uid, component, loaderUid, deviceNetwork);
     }
+
+    private void HandleUserLeftGroup(EntityUid uid, MessengerCartridgeComponent component, DeviceNetworkPacketEvent packet, EntityUid loaderUid)
+    {
+        if (!packet.Data.TryGetValue("group_id", out object? groupIdObj) ||
+            !packet.Data.TryGetValue("user_id", out object? userIdObj))
+            return;
+
+        var groupId = groupIdObj?.ToString();
+        var userId = userIdObj?.ToString();
+
+        if (string.IsNullOrEmpty(groupId))
+            return;
+
+        if (userId == component.UserId)
+        {
+            component.Groups.RemoveAll(g => g.GroupId == groupId);
+            component.MessageHistory.Remove(groupId);
+            component.MutedGroupChats.Remove(groupId);
+            component.ServerUnreadCounts.Remove(groupId);
+        }
+        else
+        {
+            var group = component.Groups.FirstOrDefault(g => g.GroupId == groupId);
+            if (group != null && !string.IsNullOrEmpty(userId))
+            {
+                group.Members.Remove(userId);
+            }
+        }
+
+        if (TryComp<DeviceNetworkComponent>(loaderUid, out var deviceNetwork))
+            RequestGroups(uid, component, loaderUid, deviceNetwork);
+
+        UpdateUiState(uid, loaderUid, component);
+    }
+
+    private void HandleGroupDeleted(EntityUid uid, MessengerCartridgeComponent component, DeviceNetworkPacketEvent packet, EntityUid loaderUid)
+    {
+        if (!packet.Data.TryGetValue("group_id", out object? groupIdObj))
+            return;
+
+        var groupId = groupIdObj?.ToString();
+        if (string.IsNullOrEmpty(groupId))
+            return;
+
+        component.Groups.RemoveAll(g => g.GroupId == groupId);
+        component.MessageHistory.Remove(groupId);
+        component.MutedGroupChats.Remove(groupId);
+        component.ServerUnreadCounts.Remove(groupId);
+
+        component.ActiveInvites.RemoveAll(inv => inv.GroupId == groupId);
+
+        if (TryComp<DeviceNetworkComponent>(loaderUid, out var deviceNetwork))
+            RequestGroups(uid, component, loaderUid, deviceNetwork);
+
+        UpdateUiState(uid, loaderUid, component);
+    }
+
+    private void HandleMessageDeleted(EntityUid uid, MessengerCartridgeComponent component, DeviceNetworkPacketEvent packet, EntityUid loaderUid)
+    {
+        if (!packet.Data.TryGetValue("message_id", out object? messageIdObj) ||
+            !packet.Data.TryGetValue("chat_id", out object? chatIdObj))
+            return;
+
+        if (!long.TryParse(messageIdObj?.ToString(), out var messageId))
+            return;
+
+        var chatId = chatIdObj?.ToString();
+        if (string.IsNullOrEmpty(chatId))
+            return;
+
+        if (component.MessageHistory.TryGetValue(chatId, out var history))
+        {
+            history.RemoveAll(m => m.MessageId == messageId);
+            if (history.Count == 0)
+                component.MessageHistory.Remove(chatId);
+        }
+
+        UpdateUiState(uid, loaderUid, component);
+    }
 }
diff --git a/Content.Server/_Sunrise/CartridgeLoader/Cartridges/MessengerCartridgeSystem.UI.cs b/Content.Server/_Sunrise/CartridgeLoader/Cartridges/MessengerCartridgeSystem.UI.cs
index c8f47d9b74..69a63d439b 100644
--- a/Content.Server/_Sunrise/CartridgeLoader/Cartridges/MessengerCartridgeSystem.UI.cs
+++ b/Content.Server/_Sunrise/CartridgeLoader/Cartridges/MessengerCartridgeSystem.UI.cs
@@ -55,7 +55,8 @@ public sealed partial class MessengerCartridgeSystem
             component.MessageHistory,
             component.MutedPersonalChats,
             component.MutedGroupChats,
-            unreadCounts
+            unreadCounts,
+            component.ActiveInvites
         );
 
         _cartridgeLoader.UpdateCartridgeUiState(loaderUid, state);
diff --git a/Content.Server/_Sunrise/Messenger/MessengerCommands.cs b/Content.Server/_Sunrise/Messenger/MessengerCommands.cs
index 4b3188dec5..4e0e24de3f 100644
--- a/Content.Server/_Sunrise/Messenger/MessengerCommands.cs
+++ b/Content.Server/_Sunrise/Messenger/MessengerCommands.cs
@@ -23,4 +23,25 @@ public static class MessengerCommands
     public const string CmdMessageReceived = "messenger_message_received";
     public const string CmdGroupCreated = "messenger_group_created";
     public const string CmdUserAddedToGroup = "messenger_user_added_to_group";
+    public const string CmdInviteReceived = "messenger_invite_received";
+    public const string CmdInviteAccepted = "messenger_invite_accepted";
+    public const string CmdInviteDeclined = "messenger_invite_declined";
+    public const string CmdInvitesList = "messenger_invites_list";
+
+    // Входящие команды для инвайтов
+    public const string CmdAcceptInvite = "messenger_accept_invite";
+    public const string CmdDeclineInvite = "messenger_decline_invite";
+
+    // Входящие команды для выхода из группы
+    public const string CmdLeaveGroup = "messenger_leave_group";
+
+    // Исходящие команды для выхода из группы
+    public const string CmdUserLeftGroup = "messenger_user_left_group";
+    public const string CmdGroupDeleted = "messenger_group_deleted";
+
+    // Входящие команды для удаления сообщений
+    public const string CmdDeleteMessage = "messenger_delete_message";
+
+    // Исходящие команды для удаления сообщений
+    public const string CmdMessageDeleted = "messenger_message_deleted";
 }
diff --git a/Content.Server/_Sunrise/Messenger/MessengerServerComponent.cs b/Content.Server/_Sunrise/Messenger/MessengerServerComponent.cs
index 35681f3817..3b355a60fb 100644
--- a/Content.Server/_Sunrise/Messenger/MessengerServerComponent.cs
+++ b/Content.Server/_Sunrise/Messenger/MessengerServerComponent.cs
@@ -34,7 +34,7 @@ public sealed partial class MessengerServerComponent : Component
     /// </summary>
     [DataField]
     [ViewVariables(VVAccess.ReadWrite)]
-    public int MaxMessageHistory = 5000;
+    public int MaxMessageHistory = 2000;
 
     /// <summary>
     /// Счетчик для генерации уникальных ID групп
@@ -66,4 +66,10 @@ public sealed partial class MessengerServerComponent : Component
     /// </summary>
     [DataField]
     public ProtoId<DeviceFrequencyPrototype> PdaFrequencyId = "PDA";
+
+    /// <summary>
+    /// Активные приглашения в группы. Ключ - ID получателя, значение - список приглашений
+    /// </summary>
+    [ViewVariables]
+    public readonly Dictionary<string, List<MessengerGroupInvite>> ActiveInvites = new();
 }
diff --git a/Content.Server/_Sunrise/Messenger/MessengerServerSystem.Groups.cs b/Content.Server/_Sunrise/Messenger/MessengerServerSystem.Groups.cs
index 367b623beb..83f97e7384 100644
--- a/Content.Server/_Sunrise/Messenger/MessengerServerSystem.Groups.cs
+++ b/Content.Server/_Sunrise/Messenger/MessengerServerSystem.Groups.cs
@@ -78,25 +78,94 @@ public sealed partial class MessengerServerSystem
         if (!component.Groups.TryGetValue(groupId, out var group))
             return;
 
-        if (group.Type != MessengerGroupType.UserCreated)
+        if (!TryComp<DeviceNetworkComponent>(uid, out var serverDevice))
+            return;
+
+        uint? pdaFrequency = null;
+        if (_prototypeManager.TryIndex(component.PdaFrequencyId, out var pdaFreq))
         {
-            if (group.AutoGroupPrototypeId != null)
+            pdaFrequency = pdaFreq.Frequency;
+        }
+
+        if (group.Type == MessengerGroupType.UserCreated)
+        {
+            if (!component.Users.TryGetValue(args.SenderAddress, out var inviter))
+                return;
+
+            if (group.OwnerId != inviter.UserId)
+                return;
+
+            if (!component.Users.TryGetValue(userId, out var invitee))
+                return;
+
+            if (group.Members.Contains(userId))
+                return;
+
+            // Проверяем, нет ли уже активного инвайта
+            if (component.ActiveInvites.TryGetValue(userId, out var existingInvites))
             {
-                if (_prototypeManager.TryIndex<MessengerAutoGroupPrototype>(group.AutoGroupPrototypeId, out var autoGroupProto))
-                {
-                    if (!autoGroupProto.AllowManualMemberManagement)
-                        return;
-                }
-                else
-                {
+                if (existingInvites.Any(inv => inv.GroupId == groupId))
+                    return;
+            }
+
+            // Создаем инвайт
+            var invite = new MessengerGroupInvite(
+                groupId,
+                group.Name,
+                inviter.UserId,
+                inviter.Name,
+                userId,
+                GetStationTime()
+            );
+
+            if (!component.ActiveInvites.TryGetValue(userId, out var invites))
+            {
+                invites = new List<MessengerGroupInvite>();
+                component.ActiveInvites[userId] = invites;
+            }
+            invites.Add(invite);
+
+            var invitePayload = new NetworkPayload
+            {
+                [DeviceNetworkConstants.Command] = MessengerCommands.CmdInviteReceived,
+                ["group_id"] = groupId,
+                ["group_name"] = group.Name,
+                ["inviter_id"] = inviter.UserId,
+                ["inviter_name"] = inviter.Name,
+                ["created_at"] = invite.CreatedAt.TotalSeconds
+            };
+
+            if (pdaFrequency.HasValue)
+            {
+                _deviceNetwork.QueuePacket(uid, userId, invitePayload, frequency: pdaFrequency, network: serverDevice.DeviceNetId);
+            }
+            else
+            {
+                _deviceNetwork.QueuePacket(uid, userId, invitePayload);
+            }
+
+            // Отправляем обновленный список инвайтов
+            SendInvitesList(uid, component, userId, serverDevice, pdaFrequency);
+            return;
+        }
+
+        // Для автоматических групп сохраняем старую логику (если разрешено)
+        if (group.AutoGroupPrototypeId != null)
+        {
+            if (_prototypeManager.TryIndex<MessengerAutoGroupPrototype>(group.AutoGroupPrototypeId, out var autoGroupProto))
+            {
+                if (!autoGroupProto.AllowManualMemberManagement)
                     return;
-                }
             }
             else
             {
                 return;
             }
         }
+        else
+        {
+            return;
+        }
 
         if (!component.Users.TryGetValue(args.SenderAddress, out var adder))
             return;
@@ -128,15 +197,6 @@ public sealed partial class MessengerServerSystem
         history.Add(systemMessage);
         TrimMessageHistory(history, component.MaxMessageHistory);
 
-        uint? pdaFrequency = null;
-        if (_prototypeManager.TryIndex(component.PdaFrequencyId, out var pdaFreq))
-        {
-            pdaFrequency = pdaFreq.Frequency;
-        }
-
-        if (!TryComp<DeviceNetworkComponent>(uid, out var serverDevice))
-            return;
-
         var messagePayload = new NetworkPayload
         {
             [DeviceNetworkConstants.Command] = MessengerCommands.CmdMessageReceived,
@@ -332,4 +392,411 @@ public sealed partial class MessengerServerSystem
             }
         }
     }
+
+    /// <summary>
+    /// Обрабатывает принятие приглашения в группу
+    /// </summary>
+    private void HandleAcceptInvite(EntityUid uid, MessengerServerComponent component, DeviceNetworkPacketEvent args)
+    {
+        if (!args.Data.TryGetValue(MessengerCommands.CmdAcceptInvite, out NetworkPayload? acceptData))
+            return;
+
+        if (!acceptData.TryGetValue("group_id", out string? groupId))
+            return;
+
+        if (!component.Users.TryGetValue(args.SenderAddress, out var user))
+            return;
+
+        if (!component.ActiveInvites.TryGetValue(user.UserId, out var invites))
+            return;
+
+        var invite = invites.FirstOrDefault(inv => inv.GroupId == groupId);
+        if (invite == null)
+            return;
+
+        if (!component.Groups.TryGetValue(groupId, out var group))
+            return;
+
+        if (group.Members.Contains(user.UserId))
+        {
+            invites.Remove(invite);
+            if (invites.Count == 0)
+                component.ActiveInvites.Remove(user.UserId);
+            return;
+        }
+
+        group.Members.Add(user.UserId);
+
+        invites.Remove(invite);
+        if (invites.Count == 0)
+            component.ActiveInvites.Remove(user.UserId);
+
+        var timestamp = GetStationTime();
+        var messageText = Loc.GetString("messenger-system-user-joined", ("userName", user.Name));
+        var messageId = GetNextMessageId(uid, component);
+        var systemMessage = new MessengerMessage("system", Loc.GetString("messenger-system-name"), messageText, timestamp, groupId, null, false, messageId);
+
+        if (!component.MessageHistory.TryGetValue(groupId, out var history))
+        {
+            history = new List<MessengerMessage>();
+            component.MessageHistory[groupId] = history;
+        }
+        history.Add(systemMessage);
+        TrimMessageHistory(history, component.MaxMessageHistory);
+
+        if (!TryComp<DeviceNetworkComponent>(uid, out var serverDevice))
+            return;
+
+        uint? pdaFrequency = null;
+        if (_prototypeManager.TryIndex(component.PdaFrequencyId, out var pdaFreq))
+        {
+            pdaFrequency = pdaFreq.Frequency;
+        }
+
+        var messagePayload = new NetworkPayload
+        {
+            [DeviceNetworkConstants.Command] = MessengerCommands.CmdMessageReceived,
+            ["sender_id"] = "system",
+            ["sender_name"] = Loc.GetString("messenger-system-name"),
+            ["content"] = messageText,
+            ["timestamp"] = timestamp.TotalSeconds,
+            ["group_id"] = groupId,
+            ["recipient_id"] = string.Empty,
+            ["is_read"] = false,
+            ["message_id"] = systemMessage.MessageId
+        };
+
+        foreach (var memberId in group.Members)
+        {
+            var isMemberChatOpen = component.OpenChats.TryGetValue(memberId, out var memberOpenChatId) && memberOpenChatId == groupId;
+
+            if (!isMemberChatOpen)
+            {
+                if (!component.UnreadCounts.TryGetValue(memberId, out var memberUnreads))
+                {
+                    memberUnreads = new Dictionary<string, int>();
+                    component.UnreadCounts[memberId] = memberUnreads;
+                }
+                memberUnreads.TryGetValue(groupId, out var currentCount);
+                memberUnreads[groupId] = currentCount + 1;
+            }
+
+            if (pdaFrequency.HasValue)
+            {
+                _deviceNetwork.QueuePacket(uid, memberId, messagePayload, frequency: pdaFrequency, network: serverDevice.DeviceNetId);
+            }
+            else
+            {
+                _deviceNetwork.QueuePacket(uid, memberId, messagePayload);
+            }
+        }
+
+        var payload = new NetworkPayload
+        {
+            [DeviceNetworkConstants.Command] = MessengerCommands.CmdUserAddedToGroup,
+            ["group_id"] = groupId,
+            ["user_id"] = user.UserId
+        };
+
+        foreach (var memberId in group.Members)
+        {
+            if (pdaFrequency.HasValue)
+            {
+                _deviceNetwork.QueuePacket(uid, memberId, payload, frequency: pdaFrequency, network: serverDevice.DeviceNetId);
+            }
+            else
+            {
+                _deviceNetwork.QueuePacket(uid, memberId, payload);
+            }
+        }
+
+        if (component.MessageHistory.TryGetValue(groupId, out var groupHistory) && groupHistory.Count > 0)
+        {
+            var sortedMessages = groupHistory.OrderBy(m => m.Timestamp)
+                .ThenBy(m => m.MessageId)
+                .ThenBy(m => m.SenderId)
+                .ToList();
+
+            var messagesData = new List<Dictionary<string, object>>();
+            foreach (var msg in sortedMessages)
+            {
+                messagesData.Add(new Dictionary<string, object>
+                {
+                    ["sender_id"] = msg.SenderId,
+                    ["sender_name"] = msg.SenderName,
+                    ["content"] = msg.Content,
+                    ["timestamp"] = msg.Timestamp.TotalSeconds,
+                    ["group_id"] = msg.GroupId ?? string.Empty,
+                    ["recipient_id"] = msg.RecipientId ?? string.Empty,
+                    ["is_read"] = msg.IsRead,
+                    ["message_id"] = msg.MessageId
+                });
+            }
+
+            var historyPayload = new NetworkPayload
+            {
+                [DeviceNetworkConstants.Command] = MessengerCommands.CmdMessagesList,
+                ["messages"] = messagesData,
+                ["chat_id"] = groupId
+            };
+
+            if (pdaFrequency.HasValue)
+            {
+                _deviceNetwork.QueuePacket(uid, user.UserId, historyPayload, frequency: pdaFrequency, network: serverDevice.DeviceNetId);
+            }
+            else
+            {
+                _deviceNetwork.QueuePacket(uid, user.UserId, historyPayload);
+            }
+        }
+
+        SendInvitesList(uid, component, user.UserId, serverDevice, pdaFrequency);
+    }
+
+    /// <summary>
+    /// Обрабатывает отклонение приглашения в группу
+    /// </summary>
+    private void HandleDeclineInvite(EntityUid uid, MessengerServerComponent component, DeviceNetworkPacketEvent args)
+    {
+        if (!args.Data.TryGetValue(MessengerCommands.CmdDeclineInvite, out NetworkPayload? declineData))
+            return;
+
+        if (!declineData.TryGetValue("group_id", out string? groupId))
+            return;
+
+        if (!component.Users.TryGetValue(args.SenderAddress, out var user))
+            return;
+
+        if (!component.ActiveInvites.TryGetValue(user.UserId, out var invites))
+            return;
+
+        var invite = invites.FirstOrDefault(inv => inv.GroupId == groupId);
+        if (invite == null)
+            return;
+
+        invites.Remove(invite);
+        if (invites.Count == 0)
+            component.ActiveInvites.Remove(user.UserId);
+
+        if (!TryComp<DeviceNetworkComponent>(uid, out var serverDevice))
+            return;
+
+        uint? pdaFrequency = null;
+        if (_prototypeManager.TryIndex(component.PdaFrequencyId, out var pdaFreq))
+        {
+            pdaFrequency = pdaFreq.Frequency;
+        }
+
+        SendInvitesList(uid, component, user.UserId, serverDevice, pdaFrequency);
+    }
+
+    /// <summary>
+    /// Отправляет список активных инвайтов пользователю
+    /// </summary>
+    private void SendInvitesList(EntityUid uid, MessengerServerComponent component, string userId, DeviceNetworkComponent serverDevice, uint? pdaFrequency)
+    {
+        var invitesList = new List<Dictionary<string, object>>();
+
+        if (component.ActiveInvites.TryGetValue(userId, out var invites))
+        {
+            foreach (var invite in invites)
+            {
+                invitesList.Add(new Dictionary<string, object>
+                {
+                    ["group_id"] = invite.GroupId,
+                    ["group_name"] = invite.GroupName,
+                    ["inviter_id"] = invite.InviterId,
+                    ["inviter_name"] = invite.InviterName,
+                    ["created_at"] = invite.CreatedAt.TotalSeconds
+                });
+            }
+        }
+
+        var payload = new NetworkPayload
+        {
+            [DeviceNetworkConstants.Command] = MessengerCommands.CmdInvitesList,
+            ["invites"] = invitesList
+        };
+
+        if (pdaFrequency.HasValue)
+        {
+            _deviceNetwork.QueuePacket(uid, userId, payload, frequency: pdaFrequency, network: serverDevice.DeviceNetId);
+        }
+        else
+        {
+            _deviceNetwork.QueuePacket(uid, userId, payload);
+        }
+    }
+
+    /// <summary>
+    /// Обрабатывает выход пользователя из группы
+    /// </summary>
+    private void HandleLeaveGroup(EntityUid uid, MessengerServerComponent component, DeviceNetworkPacketEvent args)
+    {
+        if (!args.Data.TryGetValue(MessengerCommands.CmdLeaveGroup, out NetworkPayload? leaveData))
+            return;
+
+        if (!leaveData.TryGetValue("group_id", out string? groupId))
+            return;
+
+        if (!component.Users.TryGetValue(args.SenderAddress, out var user))
+            return;
+
+        if (!component.Groups.TryGetValue(groupId, out var group))
+            return;
+
+        if (!group.Members.Contains(user.UserId))
+            return;
+
+        if (!TryComp<DeviceNetworkComponent>(uid, out var serverDevice))
+            return;
+
+        uint? pdaFrequency = null;
+        if (_prototypeManager.TryIndex(component.PdaFrequencyId, out var pdaFreq))
+        {
+            pdaFrequency = pdaFreq.Frequency;
+        }
+
+        if (group.OwnerId == user.UserId && group.Type == MessengerGroupType.UserCreated)
+        {
+            var membersToNotify = new List<string>(group.Members);
+            component.Groups.Remove(groupId);
+            component.MessageHistory.Remove(groupId);
+
+            foreach (var memberId in membersToNotify)
+            {
+                if (component.UnreadCounts.TryGetValue(memberId, out var memberUnreads))
+                {
+                    memberUnreads.Remove(groupId);
+                    if (memberUnreads.Count == 0)
+                        component.UnreadCounts.Remove(memberId);
+                }
+
+                if (component.OpenChats.TryGetValue(memberId, out var openChatId) && openChatId == groupId)
+                {
+                    component.OpenChats[memberId] = null;
+                }
+
+                var deletePayload = new NetworkPayload
+                {
+                    [DeviceNetworkConstants.Command] = MessengerCommands.CmdGroupDeleted,
+                    ["group_id"] = groupId
+                };
+
+                if (pdaFrequency.HasValue)
+                {
+                    _deviceNetwork.QueuePacket(uid, memberId, deletePayload, frequency: pdaFrequency, network: serverDevice.DeviceNetId);
+                }
+                else
+                {
+                    _deviceNetwork.QueuePacket(uid, memberId, deletePayload);
+                }
+            }
+        }
+        else
+        {
+            group.Members.Remove(user.UserId);
+
+            if (group.Type == MessengerGroupType.UserCreated)
+            {
+                var timestamp = GetStationTime();
+                var messageText = Loc.GetString("messenger-system-user-left", ("userName", user.Name));
+                var messageId = GetNextMessageId(uid, component);
+                var systemMessage = new MessengerMessage("system", Loc.GetString("messenger-system-name"), messageText, timestamp, groupId, null, false, messageId);
+
+                if (!component.MessageHistory.TryGetValue(groupId, out var history))
+                {
+                    history = new List<MessengerMessage>();
+                    component.MessageHistory[groupId] = history;
+                }
+                history.Add(systemMessage);
+                TrimMessageHistory(history, component.MaxMessageHistory);
+
+                var messagePayload = new NetworkPayload
+                {
+                    [DeviceNetworkConstants.Command] = MessengerCommands.CmdMessageReceived,
+                    ["sender_id"] = "system",
+                    ["sender_name"] = Loc.GetString("messenger-system-name"),
+                    ["content"] = messageText,
+                    ["timestamp"] = timestamp.TotalSeconds,
+                    ["group_id"] = groupId,
+                    ["recipient_id"] = string.Empty,
+                    ["is_read"] = false,
+                    ["message_id"] = systemMessage.MessageId
+                };
+
+                foreach (var memberId in group.Members)
+                {
+                    var isMemberChatOpen = component.OpenChats.TryGetValue(memberId, out var memberOpenChatId) && memberOpenChatId == groupId;
+
+                    if (!isMemberChatOpen)
+                    {
+                        if (!component.UnreadCounts.TryGetValue(memberId, out var memberUnreads))
+                        {
+                            memberUnreads = new Dictionary<string, int>();
+                            component.UnreadCounts[memberId] = memberUnreads;
+                        }
+                        memberUnreads.TryGetValue(groupId, out var currentCount);
+                        memberUnreads[groupId] = currentCount + 1;
+                    }
+
+                    if (pdaFrequency.HasValue)
+                    {
+                        _deviceNetwork.QueuePacket(uid, memberId, messagePayload, frequency: pdaFrequency, network: serverDevice.DeviceNetId);
+                    }
+                    else
+                    {
+                        _deviceNetwork.QueuePacket(uid, memberId, messagePayload);
+                    }
+                }
+            }
+
+            var payload = new NetworkPayload
+            {
+                [DeviceNetworkConstants.Command] = MessengerCommands.CmdUserLeftGroup,
+                ["group_id"] = groupId,
+                ["user_id"] = user.UserId
+            };
+
+            foreach (var memberId in group.Members)
+            {
+                if (pdaFrequency.HasValue)
+                {
+                    _deviceNetwork.QueuePacket(uid, memberId, payload, frequency: pdaFrequency, network: serverDevice.DeviceNetId);
+                }
+                else
+                {
+                    _deviceNetwork.QueuePacket(uid, memberId, payload);
+                }
+            }
+
+            var leftPayload = new NetworkPayload
+            {
+                [DeviceNetworkConstants.Command] = MessengerCommands.CmdUserLeftGroup,
+                ["group_id"] = groupId,
+                ["user_id"] = user.UserId
+            };
+
+            if (pdaFrequency.HasValue)
+            {
+                _deviceNetwork.QueuePacket(uid, user.UserId, leftPayload, frequency: pdaFrequency, network: serverDevice.DeviceNetId);
+            }
+            else
+            {
+                _deviceNetwork.QueuePacket(uid, user.UserId, leftPayload);
+            }
+
+            if (component.UnreadCounts.TryGetValue(user.UserId, out var userUnreads))
+            {
+                userUnreads.Remove(groupId);
+                if (userUnreads.Count == 0)
+                    component.UnreadCounts.Remove(user.UserId);
+            }
+
+            if (component.OpenChats.TryGetValue(user.UserId, out var userOpenChatId) && userOpenChatId == groupId)
+            {
+                component.OpenChats[user.UserId] = null;
+            }
+        }
+    }
 }
diff --git a/Content.Server/_Sunrise/Messenger/MessengerServerSystem.Messages.cs b/Content.Server/_Sunrise/Messenger/MessengerServerSystem.Messages.cs
index 77dd90b02a..699b7916de 100644
--- a/Content.Server/_Sunrise/Messenger/MessengerServerSystem.Messages.cs
+++ b/Content.Server/_Sunrise/Messenger/MessengerServerSystem.Messages.cs
@@ -1,3 +1,4 @@
+using System.Linq;
 using Content.Shared.DeviceNetwork;
 using Content.Shared.DeviceNetwork.Components;
 using Content.Shared.DeviceNetwork.Events;
@@ -199,4 +200,85 @@ public sealed partial class MessengerServerSystem
             }
         }
     }
+
+    /// <summary>
+    /// Обрабатывает удаление сообщения пользователем
+    /// </summary>
+    private void HandleDeleteMessage(EntityUid uid, MessengerServerComponent component, DeviceNetworkPacketEvent args)
+    {
+        if (!args.Data.TryGetValue(MessengerCommands.CmdDeleteMessage, out NetworkPayload? deleteData))
+            return;
+
+        if (!deleteData.TryGetValue("message_id", out object? messageIdObj) ||
+            !deleteData.TryGetValue("chat_id", out string? chatId))
+            return;
+
+        if (!long.TryParse(messageIdObj?.ToString(), out var messageId))
+            return;
+
+        if (!component.Users.TryGetValue(args.SenderAddress, out var user))
+            return;
+
+        if (!component.MessageHistory.TryGetValue(chatId, out var history))
+            return;
+
+        var message = history.FirstOrDefault(m => m.MessageId == messageId);
+        if (message == null)
+            return;
+
+        if (message.SenderId != user.UserId)
+            return;
+
+        history.Remove(message);
+
+        if (!TryComp<DeviceNetworkComponent>(uid, out var serverDevice))
+            return;
+
+        uint? pdaFrequency = null;
+        if (_prototypeManager.TryIndex(component.PdaFrequencyId, out var pdaFreq))
+        {
+            pdaFrequency = pdaFreq.Frequency;
+        }
+
+        var recipients = new HashSet<string>();
+
+        if (chatId.StartsWith("personal_"))
+        {
+            var parts = chatId.Split('_');
+            if (parts.Length >= 3)
+            {
+                recipients.Add(parts[1]);
+                recipients.Add(parts[2]);
+            }
+        }
+        else
+        {
+            if (component.Groups.TryGetValue(chatId, out var group))
+            {
+                foreach (var memberId in group.Members)
+                {
+                    recipients.Add(memberId);
+                }
+            }
+        }
+
+        var deletePayload = new NetworkPayload
+        {
+            [DeviceNetworkConstants.Command] = MessengerCommands.CmdMessageDeleted,
+            ["message_id"] = messageId,
+            ["chat_id"] = chatId
+        };
+
+        foreach (var recipientId in recipients)
+        {
+            if (pdaFrequency.HasValue)
+            {
+                _deviceNetwork.QueuePacket(uid, recipientId, deletePayload, frequency: pdaFrequency, network: serverDevice.DeviceNetId);
+            }
+            else
+            {
+                _deviceNetwork.QueuePacket(uid, recipientId, deletePayload);
+            }
+        }
+    }
 }
diff --git a/Content.Server/_Sunrise/Messenger/MessengerServerSystem.UserRegistration.cs b/Content.Server/_Sunrise/Messenger/MessengerServerSystem.UserRegistration.cs
index 21891011af..f8b1c63145 100644
--- a/Content.Server/_Sunrise/Messenger/MessengerServerSystem.UserRegistration.cs
+++ b/Content.Server/_Sunrise/Messenger/MessengerServerSystem.UserRegistration.cs
@@ -449,19 +449,6 @@ public sealed partial class MessengerServerSystem
             {
                 group.Members.Add(userId);
 
-                var timestamp = GetStationTime();
-                var messageText = Loc.GetString("messenger-system-user-added", ("userName", userName));
-                var messageId = GetNextMessageId(uid, component);
-                var systemMessage = new MessengerMessage("system", Loc.GetString("messenger-system-name"), messageText, timestamp, autoGroupProto.GroupId, null, false, messageId);
-
-                if (!component.MessageHistory.TryGetValue(autoGroupProto.GroupId, out var history))
-                {
-                    history = new List<MessengerMessage>();
-                    component.MessageHistory[autoGroupProto.GroupId] = history;
-                }
-                history.Add(systemMessage);
-                TrimMessageHistory(history, component.MaxMessageHistory);
-
                 if (!TryComp<DeviceNetworkComponent>(uid, out var serverDevice))
                     continue;
 
@@ -471,41 +458,67 @@ public sealed partial class MessengerServerSystem
                     pdaFrequency = pdaFreq.Frequency;
                 }
 
-                var messagePayload = new NetworkPayload
-                {
-                    [DeviceNetworkConstants.Command] = MessengerCommands.CmdMessageReceived,
-                    ["sender_id"] = "system",
-                    ["sender_name"] = Loc.GetString("messenger-system-name"),
-                    ["content"] = messageText,
-                    ["timestamp"] = timestamp.TotalSeconds,
-                    ["group_id"] = autoGroupProto.GroupId,
-                    ["recipient_id"] = string.Empty,
-                    ["is_read"] = false,
-                    ["message_id"] = systemMessage.MessageId
-                };
+                var isDepartmentChat = group.Type == MessengerGroupType.Automatic && group.AutoGroupPrototypeId != null;
 
-                foreach (var memberId in group.Members)
+                if (!isDepartmentChat)
                 {
-                    var isMemberChatOpen = component.OpenChats.TryGetValue(memberId, out var memberOpenChatId) && memberOpenChatId == autoGroupProto.GroupId;
+                    var timestamp = GetStationTime();
+                    var messageText = Loc.GetString("messenger-system-user-added", ("userName", userName));
+                    var messageId = GetNextMessageId(uid, component);
+                    var systemMessage = new MessengerMessage("system", Loc.GetString("messenger-system-name"), messageText, timestamp, autoGroupProto.GroupId, null, false, messageId);
 
-                    if (!isMemberChatOpen)
+                    if (!component.MessageHistory.TryGetValue(autoGroupProto.GroupId, out var history))
                     {
-                        if (!component.UnreadCounts.TryGetValue(memberId, out var memberUnreads))
+                        history = new List<MessengerMessage>();
+                        component.MessageHistory[autoGroupProto.GroupId] = history;
+                    }
+                    history.Add(systemMessage);
+                    TrimMessageHistory(history, component.MaxMessageHistory);
+                }
+
+                if (!isDepartmentChat)
+                {
+                    var timestamp = GetStationTime();
+                    var messageText = Loc.GetString("messenger-system-user-added", ("userName", userName));
+                    var messageId = GetNextMessageId(uid, component);
+                    var systemMessage = new MessengerMessage("system", Loc.GetString("messenger-system-name"), messageText, timestamp, autoGroupProto.GroupId, null, false, messageId);
+
+                    var messagePayload = new NetworkPayload
+                    {
+                        [DeviceNetworkConstants.Command] = MessengerCommands.CmdMessageReceived,
+                        ["sender_id"] = "system",
+                        ["sender_name"] = Loc.GetString("messenger-system-name"),
+                        ["content"] = messageText,
+                        ["timestamp"] = timestamp.TotalSeconds,
+                        ["group_id"] = autoGroupProto.GroupId,
+                        ["recipient_id"] = string.Empty,
+                        ["is_read"] = false,
+                        ["message_id"] = systemMessage.MessageId
+                    };
+
+                    foreach (var memberId in group.Members)
+                    {
+                        var isMemberChatOpen = component.OpenChats.TryGetValue(memberId, out var memberOpenChatId) && memberOpenChatId == autoGroupProto.GroupId;
+
+                        if (!isMemberChatOpen)
                         {
-                            memberUnreads = new Dictionary<string, int>();
-                            component.UnreadCounts[memberId] = memberUnreads;
+                            if (!component.UnreadCounts.TryGetValue(memberId, out var memberUnreads))
+                            {
+                                memberUnreads = new Dictionary<string, int>();
+                                component.UnreadCounts[memberId] = memberUnreads;
+                            }
+                            memberUnreads.TryGetValue(autoGroupProto.GroupId, out var currentCount);
+                            memberUnreads[autoGroupProto.GroupId] = currentCount + 1;
                         }
-                        memberUnreads.TryGetValue(autoGroupProto.GroupId, out var currentCount);
-                        memberUnreads[autoGroupProto.GroupId] = currentCount + 1;
-                    }
 
-                    if (pdaFrequency.HasValue)
-                    {
-                        _deviceNetwork.QueuePacket(uid, memberId, messagePayload, frequency: pdaFrequency, network: serverDevice.DeviceNetId);
-                    }
-                    else
-                    {
-                        _deviceNetwork.QueuePacket(uid, memberId, messagePayload);
+                        if (pdaFrequency.HasValue)
+                        {
+                            _deviceNetwork.QueuePacket(uid, memberId, messagePayload, frequency: pdaFrequency, network: serverDevice.DeviceNetId);
+                        }
+                        else
+                        {
+                            _deviceNetwork.QueuePacket(uid, memberId, messagePayload);
+                        }
                     }
                 }
 
diff --git a/Content.Server/_Sunrise/Messenger/MessengerServerSystem.cs b/Content.Server/_Sunrise/Messenger/MessengerServerSystem.cs
index 89d43a519a..1eb52e4ed8 100644
--- a/Content.Server/_Sunrise/Messenger/MessengerServerSystem.cs
+++ b/Content.Server/_Sunrise/Messenger/MessengerServerSystem.cs
@@ -118,6 +118,18 @@ public sealed partial class MessengerServerSystem : EntitySystem
             case MessengerCommands.CmdGetMessages:
                 HandleGetMessages(uid, component, args);
                 break;
+            case MessengerCommands.CmdAcceptInvite:
+                HandleAcceptInvite(uid, component, args);
+                break;
+            case MessengerCommands.CmdDeclineInvite:
+                HandleDeclineInvite(uid, component, args);
+                break;
+            case MessengerCommands.CmdLeaveGroup:
+                HandleLeaveGroup(uid, component, args);
+                break;
+            case MessengerCommands.CmdDeleteMessage:
+                HandleDeleteMessage(uid, component, args);
+                break;
             default:
                 Sawmill.Warning($"Unknown command received: {command} from {args.SenderAddress}");
                 break;
diff --git a/Content.Shared/_Sunrise/CartridgeLoader/Cartridges/MessengerUiMessageEvent.cs b/Content.Shared/_Sunrise/CartridgeLoader/Cartridges/MessengerUiMessageEvent.cs
index 6f83b7dd18..df526b1a83 100644
--- a/Content.Shared/_Sunrise/CartridgeLoader/Cartridges/MessengerUiMessageEvent.cs
+++ b/Content.Shared/_Sunrise/CartridgeLoader/Cartridges/MessengerUiMessageEvent.cs
@@ -17,6 +17,7 @@ public sealed class MessengerUiMessageEvent : CartridgeMessageEvent
     public readonly string? UserId;
     public readonly string? ChatId;
     public readonly bool? IsMuted;
+    public readonly long? MessageId;
 
     public MessengerUiMessageEvent(
         MessengerUiAction action,
@@ -26,7 +27,8 @@ public sealed class MessengerUiMessageEvent : CartridgeMessageEvent
         string? groupName = null,
         string? userId = null,
         string? chatId = null,
-        bool? isMuted = null)
+        bool? isMuted = null,
+        long? messageId = null)
     {
         Action = action;
         RecipientId = recipientId;
@@ -36,6 +38,7 @@ public sealed class MessengerUiMessageEvent : CartridgeMessageEvent
         UserId = userId;
         ChatId = chatId;
         IsMuted = isMuted;
+        MessageId = messageId;
     }
 }
 
@@ -52,5 +55,9 @@ public enum MessengerUiAction
     RequestUsers,
     RequestGroups,
     RequestMessages,
-    ToggleMute
+    ToggleMute,
+    AcceptInvite,
+    DeclineInvite,
+    LeaveGroup,
+    DeleteMessage
 }
diff --git a/Content.Shared/_Sunrise/CartridgeLoader/Cartridges/MessengerUiState.cs b/Content.Shared/_Sunrise/CartridgeLoader/Cartridges/MessengerUiState.cs
index d27f7b160e..141b7a4ed8 100644
--- a/Content.Shared/_Sunrise/CartridgeLoader/Cartridges/MessengerUiState.cs
+++ b/Content.Shared/_Sunrise/CartridgeLoader/Cartridges/MessengerUiState.cs
@@ -54,6 +54,11 @@ public sealed class MessengerUiState : BoundUserInterfaceState
     /// </summary>
     public Dictionary<string, int> UnreadCounts { get; }
 
+    /// <summary>
+    /// Активные приглашения в группы
+    /// </summary>
+    public List<MessengerGroupInvite> ActiveInvites { get; }
+
     public MessengerUiState(
         bool isRegistered,
         bool serverAvailable,
@@ -63,7 +68,8 @@ public sealed class MessengerUiState : BoundUserInterfaceState
         Dictionary<string, List<MessengerMessage>> messageHistory,
         HashSet<string> mutedPersonalChats,
         HashSet<string> mutedGroupChats,
-        Dictionary<string, int> unreadCounts)
+        Dictionary<string, int> unreadCounts,
+        List<MessengerGroupInvite> activeInvites)
     {
         IsRegistered = isRegistered;
         ServerAvailable = serverAvailable;
@@ -74,5 +80,6 @@ public sealed class MessengerUiState : BoundUserInterfaceState
         MutedPersonalChats = mutedPersonalChats;
         MutedGroupChats = mutedGroupChats;
         UnreadCounts = unreadCounts;
+        ActiveInvites = activeInvites;
     }
 }
diff --git a/Content.Shared/_Sunrise/Messenger/MessengerGroupInvite.cs b/Content.Shared/_Sunrise/Messenger/MessengerGroupInvite.cs
new file mode 100644
index 0000000000..5c2b4708b2
--- /dev/null
+++ b/Content.Shared/_Sunrise/Messenger/MessengerGroupInvite.cs
@@ -0,0 +1,50 @@
+using Robust.Shared.Serialization;
+
+namespace Content.Shared._Sunrise.Messenger;
+
+/// <summary>
+/// Приглашение в группу мессенджера
+/// </summary>
+[Serializable, NetSerializable]
+public sealed class MessengerGroupInvite
+{
+    /// <summary>
+    /// ID группы, в которую приглашают
+    /// </summary>
+    public string GroupId { get; set; }
+
+    /// <summary>
+    /// Название группы
+    /// </summary>
+    public string GroupName { get; set; }
+
+    /// <summary>
+    /// ID пользователя, который отправил приглашение
+    /// </summary>
+    public string InviterId { get; set; }
+
+    /// <summary>
+    /// Имя пользователя, который отправил приглашение
+    /// </summary>
+    public string InviterName { get; set; }
+
+    /// <summary>
+    /// ID пользователя, которому отправлено приглашение
+    /// </summary>
+    public string InviteeId { get; set; }
+
+    /// <summary>
+    /// Время создания приглашения
+    /// </summary>
+    public TimeSpan CreatedAt { get; set; }
+
+    public MessengerGroupInvite(string groupId, string groupName, string inviterId, string inviterName, string inviteeId, TimeSpan createdAt)
+    {
+        GroupId = groupId;
+        GroupName = groupName;
+        InviterId = inviterId;
+        InviterName = inviterName;
+        InviteeId = inviteeId;
+        CreatedAt = createdAt;
+    }
+}
diff --git a/Resources/Locale/en-US/_strings/cartridge-loader/messenger.ftl b/Resources/Locale/en-US/_strings/cartridge-loader/messenger.ftl
index 9b7564e745..56b54b8ef5 100644
--- a/Resources/Locale/en-US/_strings/cartridge-loader/messenger.ftl
+++ b/Resources/Locale/en-US/_strings/cartridge-loader/messenger.ftl
@@ -4,6 +4,8 @@ messenger-status-connected = Connected
 messenger-search-placeholder = Search...
 messenger-tab-personal = Personal
 messenger-tab-groups = Groups
+messenger-tab-invites = Invites
+messenger-no-invites = No invites
 messenger-create-group-button = Create group
 messenger-chat-select = Select chat
 messenger-mute-tooltip = Mute
@@ -46,3 +48,13 @@ messenger-emoji-favorite-hint = ПКМ по общему списку для д
 messenger-emoji-all-title = All emojis
 messenger-user-unknown = Unknown
 messenger-system-name = System
+messenger-leave-group = Leave group
+messenger-invite-member-button = Invite
+messenger-invites-header = Invites
+messenger-invite-info = { $inviter } invites you
+messenger-invite-accept = Accept
+messenger-invite-decline = Decline
+messenger-invite-user-to-group-title = Invite to { $groupName }
+messenger-delete-message = Delete message
+messenger-system-user-joined = { $userName } joined the group
+messenger-system-user-left = { $userName } left the group
diff --git a/Resources/Locale/ru-RU/_strings/cartridge-loader/messenger.ftl b/Resources/Locale/ru-RU/_strings/cartridge-loader/messenger.ftl
index 0f4c068d0a..9634bd8050 100644
--- a/Resources/Locale/ru-RU/_strings/cartridge-loader/messenger.ftl
+++ b/Resources/Locale/ru-RU/_strings/cartridge-loader/messenger.ftl
@@ -4,6 +4,8 @@ messenger-status-connected = Подключено
 messenger-search-placeholder = Поиск...
 messenger-tab-personal = Личные
 messenger-tab-groups = Группы
+messenger-tab-invites = Приглашения
+messenger-no-invites = Нет приглашений
 messenger-create-group-button = Создать группу
 messenger-chat-select = Выберите чат
 messenger-mute-tooltip = Отключить звук
@@ -47,3 +49,13 @@ messenger-emoji-favorite-hint = ПКМ по общему списку для д
 messenger-emoji-all-title = Все смайлики
 messenger-user-unknown = Неизвестно
 messenger-system-name = Система
+messenger-leave-group = Выйти из группы
+messenger-invite-member-button = Пригласить
+messenger-invites-header = Приглашения
+messenger-invite-info = { $inviter } приглашает вас
+messenger-invite-accept = Принять
+messenger-invite-decline = Отклонить
+messenger-invite-user-to-group-title = Пригласить в { $groupName }
+messenger-delete-message = Удалить сообщение
+messenger-system-user-joined = { $userName } присоединился(ась) к группе
+messenger-system-user-left = { $userName } покинул(а) группу