Структура

backend/src/Contracts/Auth/Domain/UserStatusChangedDomainEvent.cs

@@ -0,0 +1,8 @@
+using Knot.Shared.Kernel;
+
+namespace Knot.Contracts.Auth.Domain;
+
+/// <summary>
+/// Доменное событие: изменился статус пользователя (онлайн/офлайн).
+/// </summary>
+public sealed record UserStatusChangedDomainEvent(Guid UserId, bool IsOnline, DateTime LastSeen) : IDomainEvent;

backend/src/Contracts/Conversations/Application/Abstractions/IChatsUnitOfWork.cs

@@ -0,0 +1,7 @@
+using Knot.Shared.Kernel;
+
+namespace Knot.Contracts.Conversations.Application.Abstractions;
+
+public interface IChatsUnitOfWork : IUnitOfWork
+{
+}

backend/src/Contracts/Conversations/Application/Abstractions/IUserStatusService.cs

@@ -0,0 +1,8 @@
+using System;
+
+namespace Knot.Contracts.Conversations.Application.Abstractions;
+
+public interface IUserStatusService
+{
+    bool IsUserOnline(string userId);
+}

backend/src/Contracts/Conversations/Domain/Chat.cs

@@ -0,0 +1,146 @@
+using Knot.Shared.Kernel;
+
+namespace Knot.Contracts.Conversations.Domain;
+
+public sealed record ChatCreatedDomainEvent(Chat Chat) : IDomainEvent;
+public sealed record ChatMemberAddedDomainEvent(Guid ChatId, Guid UserId) : IDomainEvent;
+
+/// <summary>
+/// Тип чата: личный или групповой.
+/// </summary>
+public enum ChatType
+{
+    Personal,
+    Group,
+    Favorites
+}
+
+/// <summary>
+/// Роль участника в чате.
+/// </summary>
+public static class ChatRole
+{
+    public const string Owner = "owner";
+    public const string Admin = "admin";
+    public const string Member = "member";
+}
+
+/// <summary>
+/// Сущность чата (Агрегат).
+/// </summary>
+public sealed class Chat : AggregateRoot<Guid>
+{
+    public ChatType Type { get; private set; }
+    public string? Name { get; private set; }
+    public string? Description { get; private set; }
+    public string? Avatar { get; private set; }
+    public DateTime CreatedAt { get; private set; }
+    public long LastMessageSequenceId { get; private set; }
+
+    private readonly List<ChatMember> _members = new();
+    public IReadOnlyCollection<ChatMember> Members => _members.AsReadOnly();
+
+    private Chat(Guid id, ChatType type, string? name, string? avatar, string? description = null) : base(id)
+    {
+        Type = type;
+        Name = name;
+        Avatar = avatar;
+        Description = description;
+        CreatedAt = DateTime.UtcNow;
+    }
+
+    public static Chat CreatePersonal()
+    {
+        var chat = new Chat(Guid.NewGuid(), ChatType.Personal, null, null);
+        chat.RaiseDomainEvent(new ChatCreatedDomainEvent(chat));
+        return chat;
+    }
+
+    public static Chat CreateGroup(string name, string? avatar = null)
+    {
+        var chat = new Chat(Guid.NewGuid(), ChatType.Group, name, avatar);
+        chat.RaiseDomainEvent(new ChatCreatedDomainEvent(chat));
+        return chat;
+    }
+
+    public static Chat Create(string? name, ChatType type, string? avatar = null, string? description = null)
+    {
+        var chat = new Chat(Guid.NewGuid(), type, name, avatar, description);
+        chat.RaiseDomainEvent(new ChatCreatedDomainEvent(chat));
+        return chat;
+    }
+
+    public void AddMember(Guid userId, string role = "member")
+    {
+        if (_members.Any(m => m.UserId == userId))
+        {
+            return;
+        }
+
+        _members.Add(new ChatMember(Id, userId, role));
+        RaiseDomainEvent(new ChatMemberAddedDomainEvent(Id, userId));
+    }
+
+    public void RemoveMember(Guid userId)
+    {
+        var member = _members.FirstOrDefault(m => m.UserId == userId);
+        if (member != null)
+        {
+            _members.Remove(member);
+        }
+    }
+
+    public void UpdateName(string name) => Name = name;
+
+    public void UpdateDescription(string? description) => Description = description;
+
+    public void UpdateAvatar(string? avatarUrl) => Avatar = avatarUrl;
+
+    public long IncrementSequenceId()
+    {
+        return ++LastMessageSequenceId;
+    }
+}
+
+/// <summary>
+/// Участник чата.
+/// </summary>
+public sealed class ChatMember : Entity<Guid>
+{
+    public Guid ChatId { get; private set; }
+    public Guid UserId { get; private set; }
+    public string Role { get; private set; }
+    public DateTime JoinedAt { get; private set; }
+    public bool IsPinned { get; private set; }
+    public bool IsMuted { get; private set; }
+    
+    public Guid? LastReadMessageId { get; private set; }
+    public long LastReadSequenceId { get; private set; }
+    public Guid? LastDeliveredMessageId { get; private set; }
+
+    private ChatMember() : base(Guid.Empty) { Role = "member"; }
+
+    internal ChatMember(Guid chatId, Guid userId, string role) : base(Guid.NewGuid())
+    {
+        ChatId = chatId;
+        UserId = userId;
+        Role = role;
+        JoinedAt = DateTime.UtcNow;
+    }
+
+    public void TogglePin() => IsPinned = !IsPinned;
+
+    public void UpdateReadCursor(Guid messageId, long sequenceId)
+    {
+        if (sequenceId > LastReadSequenceId)
+        {
+            LastReadMessageId = messageId;
+            LastReadSequenceId = sequenceId;
+        }
+    }
+
+    public void UpdateDeliveredCursor(Guid messageId)
+    {
+        LastDeliveredMessageId = messageId;
+    }
+}

backend/src/Contracts/Conversations/Domain/Folder.cs

@@ -0,0 +1,101 @@
+using System;
+using System.Collections.Generic;
+using Knot.Shared.Kernel;
+
+namespace Knot.Contracts.Conversations.Domain;
+
+/// <summary>
+/// Сущность папки для группировки чатов.
+/// </summary>
+public sealed class Folder : AggregateRoot<Guid>
+{
+    public string Name { get; private set; }
+    public string? Icon { get; private set; }
+    public bool IsDefault { get; private set; }
+    public FolderType Type { get; private set; }
+
+    public Folder(Guid id, string name, string? icon = null, bool isDefault = false, FolderType type = FolderType.Custom)
+        : base(id)
+    {
+        Name = name;
+        Icon = icon;
+        IsDefault = isDefault;
+        Type = type;
+    }
+
+    public void Update(string name, string? icon)
+    {
+        if (IsDefault) throw new InvalidOperationException("Cannot rename default folders.");
+        Name = name;
+        Icon = icon;
+    }
+}
+
+public enum FolderType
+{
+    All,
+    New,
+    Muted,
+    Custom
+}
+
+/// <summary>
+/// Настройки конкретного чата для конкретного пользователя.
+/// </summary>
+public sealed class UserChatSettings : Entity<Guid>
+{
+    public Guid UserId { get; private set; }
+    public Guid ChatId { get; private set; }
+    
+    private readonly List<Guid> _folderIds = new();
+    public IReadOnlyCollection<Guid> FolderIds => _folderIds.AsReadOnly();
+
+    public bool IsMuted { get; private set; }
+
+    private UserChatSettings() : base(Guid.NewGuid()) { }
+
+    public UserChatSettings(Guid userId, Guid chatId) : base(Guid.NewGuid())
+    {
+        UserId = userId;
+        ChatId = chatId;
+    }
+
+    public static UserChatSettings Create(Guid userId, Guid chatId) => new(userId, chatId);
+
+    public void AddToFolder(Guid folderId)
+    {
+        if (!_folderIds.Contains(folderId)) _folderIds.Add(folderId);
+    }
+
+    public void RemoveFromFolder(Guid folderId)
+    {
+        _folderIds.Remove(folderId);
+    }
+
+    public void SetMute(bool isMuted) => IsMuted = isMuted;
+}
+
+/// <summary>
+/// Глобальные настройки папок пользователя.
+/// </summary>
+public sealed class UserFolderSettings : AggregateRoot<Guid>
+{
+    public Guid UserId { get; private set; }
+    public List<Guid> HiddenDefaultFolderIds { get; private set; } = new();
+    public List<Guid> CustomFolderIds { get; private set; } = new();
+
+    public UserFolderSettings(Guid userId) : base(Guid.NewGuid())
+    {
+        UserId = userId;
+    }
+
+    public void HideFolder(Guid folderId)
+    {
+        if (!HiddenDefaultFolderIds.Contains(folderId)) HiddenDefaultFolderIds.Add(folderId);
+    }
+
+    public void ShowFolder(Guid folderId)
+    {
+        HiddenDefaultFolderIds.Remove(folderId);
+    }
+}

backend/src/Contracts/Conversations/Domain/IChatRepository.cs

@@ -0,0 +1,39 @@
+using Knot.Contracts.Conversations.Domain;
+
+namespace Knot.Contracts.Conversations.Domain;
+
+public interface IChatRepository
+{
+    void Add(Chat chat);
+    void Update(Chat chat);
+    void Remove(Chat chat);
+    Task<Chat?> GetByIdAsync(Guid id, CancellationToken cancellationToken);
+    Task<Chat?> GetFavoritesAsync(Guid userId, CancellationToken cancellationToken);
+    Task<List<Chat>> GetUserChatsAsync(Guid userId, CancellationToken cancellationToken);
+}
+
+public interface IFolderRepository
+{
+    void Add(Folder folder);
+    void Update(Folder folder);
+    void Remove(Folder folder);
+    Task<Folder?> GetByIdAsync(Guid id, CancellationToken cancellationToken);
+    Task<List<Folder>> GetUserFoldersAsync(Guid userId, CancellationToken cancellationToken);
+}
+
+public interface IUserChatSettingsRepository
+{
+    void Add(UserChatSettings settings);
+    void Update(UserChatSettings settings);
+    void Remove(UserChatSettings settings);
+    void RemoveRange(IEnumerable<UserChatSettings> settings);
+    Task<UserChatSettings?> GetAsync(Guid userId, Guid chatId, CancellationToken cancellationToken);
+    Task<List<UserChatSettings>> GetByUserIdAsync(Guid userId, CancellationToken cancellationToken);
+}
+
+public interface IUserFolderSettingsRepository
+{
+    Task<UserFolderSettings?> GetByUserIdAsync(Guid userId, CancellationToken cancellationToken);
+    Task UpdateAsync(UserFolderSettings settings, CancellationToken cancellationToken);
+    Task RemoveByUserIdAsync(Guid userId, CancellationToken cancellationToken);
+}

backend/src/Contracts/Conversations/Knot.Contracts.Conversations.csproj

@@ -8,6 +8,7 @@
 
   <ItemGroup>
     <ProjectReference Include="..\..\Shared\Knot.Shared.Kernel\Knot.Shared.Kernel.csproj" />
+    <ProjectReference Include="..\Messaging\Knot.Contracts.Messaging.csproj" />
   </ItemGroup>
 
   <ItemGroup>

backend/src/Contracts/Messaging/Application/Abstractions/IChatAccessProvider.cs

@@ -0,0 +1,11 @@
+using System;
+using System.Collections.Generic;
+using System.Threading;
+using System.Threading.Tasks;
+
+namespace Knot.Contracts.Messaging.Application.Abstractions;
+
+public interface IChatAccessProvider 
+{ 
+    Task<List<Guid>> GetValidChatIdsForUserAsync(Guid userId, CancellationToken ct); 
+}

backend/src/Contracts/Messaging/Application/Abstractions/IMessageNotifier.cs

@@ -0,0 +1,6 @@
+namespace Knot.Contracts.Messaging.Application.Abstractions;
+
+public interface IMessageNotifier 
+{ 
+    Task NotifyNewMessageAsync(Guid chatId, object messagePayload, CancellationToken cancellationToken); 
+}

backend/src/Contracts/Messaging/Application/Abstractions/IMessageRepository.cs

@@ -0,0 +1,21 @@
+using Knot.Contracts.Messaging.Domain;
+
+namespace Knot.Contracts.Messaging.Application.Abstractions;
+
+public interface IMessageRepository
+{
+    void Add(Message message);
+    Task<Message?> GetByIdAsync(Guid id, CancellationToken cancellationToken);
+    Task<List<Message>> GetChatMessagesAsync(Guid chatId, int limit, int offset, CancellationToken cancellationToken);
+    Task<Message?> GetLatestChatMessageAsync(Guid chatId, CancellationToken cancellationToken);
+    Task<List<Message>> SearchMessagesAsync(string query, Guid? chatId, Guid requestingUserId, CancellationToken cancellationToken);
+
+    Task<List<Message>> GetChatMessagesCursorAsync(Guid chatId, DateTime? cursor, int limit, CancellationToken cancellationToken);
+    Task<Message?> GetLastStoryMessageAsync(Guid chatId, Guid storyId, CancellationToken cancellationToken);
+
+    Task UpdateAsync(Message message, CancellationToken cancellationToken);
+    Task<List<Message>> GetAllMessagesAsync(CancellationToken cancellationToken);
+    Task DeleteChatMessagesAsync(Guid chatId, CancellationToken cancellationToken);
+    Task DeleteUserMessagesAsync(Guid userId, CancellationToken cancellationToken);
+    Task RemoveAsync(Guid id, CancellationToken cancellationToken);
+}

backend/src/Contracts/Messaging/Application/Abstractions/IUserStatsService.cs

@@ -0,0 +1,16 @@
+using System;
+using System.Collections.Generic;
+using System.Threading;
+using System.Threading.Tasks;
+
+namespace Knot.Contracts.Messaging.Application.Abstractions;
+
+public record UserStats(int MessageCount, long StorageSize);
+
+public interface IUserStatsService
+{
+    Task<Dictionary<Guid, UserStats>> GetStatsForUsersAsync(IEnumerable<Guid> userIds, CancellationToken ct = default);
+    Task<long> GetTotalStorageSizeAsync(CancellationToken ct = default);
+    Task<int> GetCountOrphanedMessagesAsync(HashSet<Guid> activeChatIds, CancellationToken ct = default);
+    Task<long> GetOrphanedMediaSizeAsync(HashSet<string> validFileIds, CancellationToken ct = default);
+}

backend/src/Contracts/Messaging/Domain/DeletedMessage.cs

@@ -0,0 +1,20 @@
+using Knot.Shared.Kernel;
+
+namespace Knot.Contracts.Messaging.Domain;
+
+/// <summary>
+/// Запись о том, что конкретный пользователь удалил у себя сообщение.
+/// </summary>
+public sealed class DeletedMessage : Entity<Guid>
+{
+    public Guid MessageId { get; private set; }
+    public Guid UserId { get; private set; }
+
+    internal DeletedMessage(Guid messageId, Guid userId) : base(Guid.NewGuid())
+    {
+        MessageId = messageId;
+        UserId = userId;
+    }
+
+    private DeletedMessage() : base(Guid.Empty) { }
+}

backend/src/Contracts/Messaging/Domain/IMessageReactionRepository.cs

@@ -0,0 +1,9 @@
+namespace Knot.Contracts.Messaging.Domain;
+
+public interface IMessageReactionRepository
+{
+    Task AddAsync(MessageReaction reaction, CancellationToken cancellationToken);
+    Task RemoveAsync(Guid messageId, Guid userId, string emoji, CancellationToken cancellationToken);
+    Task<List<MessageReaction>> GetReactionsForMessageAsync(Guid messageId, CancellationToken cancellationToken);
+    Task<List<MessageReaction>> GetReactionsForMessagesAsync(IEnumerable<Guid> messageIds, CancellationToken cancellationToken);
+}

backend/src/Contracts/Messaging/Domain/MediaType.cs

@@ -0,0 +1,9 @@
+namespace Knot.Contracts.Messaging.Domain;
+
+public enum MediaType
+{
+    Image,
+    Video,
+    Voice,
+    File
+}

backend/src/Contracts/Messaging/Domain/Message.cs

@@ -0,0 +1,126 @@
+using System;
+using System.Collections.Generic;
+using Knot.Shared.Kernel;
+
+namespace Knot.Contracts.Messaging.Domain;
+
+public abstract class Message : AggregateRoot<Guid>
+{
+    public Guid ChatId { get; protected set; }
+    public Guid SenderId { get; protected set; }
+    public DateTime CreatedAt { get; protected set; }
+    public long SequenceId { get; protected set; }
+    public void SetSequenceId(long sequenceId) => SequenceId = sequenceId;
+    public Guid? ReplyToId { get; protected set; }
+    public Guid? ForwardedFromId { get; protected set; }
+    public MessageState State { get; protected set; }
+    public abstract string Type { get; }
+    public abstract string? Content { get; protected set; }
+    public virtual string? Quote { get; protected set; } = null;
+    public virtual Guid? StoryId => null;
+    public virtual string? StoryMediaUrl => null;
+    public virtual string? StoryMediaType => null;
+    public virtual IReadOnlyCollection<Media> Media => Array.Empty<Media>();
+    public bool IsEdited => HasState(MessageState.IsEdited);
+    public bool IsDeleted => HasState(MessageState.IsDeleted);
+    public bool IsDeletedForUser(Guid userId) => _deletedFor.Exists(d => d.UserId == userId);
+    protected List<DeletedMessage> _deletedFor = new();
+    public IReadOnlyCollection<DeletedMessage> DeletedFor => _deletedFor.AsReadOnly();
+    protected Message() : base(Guid.Empty) { }
+    protected Message(Guid id, Guid chatId, Guid senderId, Guid? replyToId, Guid? forwardedFromId, DateTime createdAt, bool isImported) : base(id)
+    {
+        ChatId = chatId;
+        SenderId = senderId;
+        ReplyToId = replyToId;
+        ForwardedFromId = forwardedFromId;
+        CreatedAt = createdAt;
+        if (isImported) AddState(MessageState.IsImported);
+    }
+    public void AddState(MessageState state) => State |= state;
+    public void RemoveState(MessageState state) => State &= ~state;
+    public bool HasState(MessageState state) => (State & state) == state;
+    public virtual void Delete() => AddState(MessageState.IsDeleted);
+    public virtual void Edit(string newContent) { Content = newContent; AddState(MessageState.IsEdited); }
+    public void DeleteForUser(Guid userId) { if (!_deletedFor.Exists(x => x.UserId == userId)) _deletedFor.Add(new DeletedMessage(Id, userId)); }
+}
+
+public class Media
+{
+    public Guid Id { get; set; }
+    public string Type { get; set; } = string.Empty;
+    public string? Url { get; set; }
+    public string? ThumbnailUrl { get; set; }
+    public long? Size { get; set; }
+    public int Width { get; set; }
+    public int Height { get; set; }
+    public string? FileId { get; set; }
+    public string? Filename { get; set; }
+    public string? Duration { get; set; }
+}
+
+public class TextMessage : Message
+{
+    public override string Type => "text";
+    public override string? Content { get; protected set; }
+    public TextMessage() : base() { }
+    public TextMessage(Guid id, Guid chatId, Guid senderId, string content, Guid? replyToId, Guid? forwardedFromId, DateTime createdAt, bool isImported = false)
+        : base(id, chatId, senderId, replyToId, forwardedFromId, createdAt, isImported) => Content = content;
+    public TextMessage(Guid id, Guid chatId, Guid senderId, string content, Guid? replyToId, string? quote, Guid? forwardedFromId, DateTime createdAt, bool isImported = false)
+        : this(id, chatId, senderId, content, replyToId, forwardedFromId, createdAt, isImported) => Quote = quote;
+}
+
+public class MediaMessage : Message
+{
+    public override string Type => MediaType.ToString().ToLower();
+    public override string? Content { get; protected set; }
+    public string? Caption { get => Content; private set => Content = value; }
+    public MediaType MediaType { get; private set; }
+    private List<Media> _media = new();
+    public override IReadOnlyCollection<Media> Media => _media.AsReadOnly();
+    private MediaMessage() : base() { MediaType = MediaType.File; }
+    public MediaMessage(Guid id, Guid chatId, Guid senderId, MediaType mediaType, string? caption, Guid? replyToId, Guid? forwardedFromId, DateTime createdAt, bool isImported)
+        : base(id, chatId, senderId, replyToId, forwardedFromId, createdAt, isImported) { MediaType = mediaType; Caption = caption; }
+    public MediaMessage(Guid id, Guid chatId, Guid senderId, string mediaType, string? caption, Guid? replyToId, Guid? forwardedFromId, DateTime createdAt, bool isImported)
+        : this(id, chatId, senderId, Enum.TryParse<MediaType>(mediaType, true, out var mt) ? mt : MediaType.File, caption, replyToId, forwardedFromId, createdAt, isImported) { }
+    public void AddMedia(string type, string url, string? filename, long? size) => _media.Add(new Media { Type = type, Url = url, FileId = filename, Size = size });
+    public override void Edit(string newCaption) => base.Edit(newCaption);
+    public override void Delete() { Caption = null; base.Delete(); }
+}
+
+public class StoryMessage : Message
+{
+    public override string Type => "story";
+    public override string? Content { get; protected set; }
+    public override Guid? StoryId { get; }
+    public string? InternalStoryMediaUrl { get; private set; }
+    public override string? StoryMediaUrl => InternalStoryMediaUrl;
+    public override string? StoryMediaType { get; }
+    public StoryMessage() : base() { }
+    public StoryMessage(Guid id, Guid chatId, Guid senderId, Guid storyId, string? storyMediaUrl, string? storyMediaType, DateTime createdAt)
+        : base(id, chatId, senderId, null, null, createdAt, false) { StoryId = storyId; InternalStoryMediaUrl = storyMediaUrl; StoryMediaType = storyMediaType; }
+    public StoryMessage(Guid id, Guid chatId, Guid senderId, Guid storyId, string? storyMediaUrl, string? storyMediaType, string? content, Guid? replyToId, Guid? forwardedFromId, DateTime createdAt, bool isImported)
+        : this(id, chatId, senderId, storyId, storyMediaUrl, storyMediaType, createdAt) { Content = content; ReplyToId = replyToId; ForwardedFromId = forwardedFromId; if (isImported) AddState(MessageState.IsImported); }
+}
+
+public class PollMessage : Message
+{
+    public override string Type => "poll";
+    public override string? Content { get; protected set; }
+    public List<PollOption> Options { get; } = new();
+    public List<PollVote> Votes { get; } = new();
+    public bool IsMultipleChoice { get; set; }
+    public DateTime? ExpiresAt { get; set; }
+    public bool IsClosed { get; set; }
+    public PollMessage() : base() { }
+    public PollMessage(Guid id, Guid chatId, Guid senderId, string? question, List<string>? options, bool isAnonymous, bool isMultiple, DateTime? expiresAt, Guid? replyToId, Guid? forwardedFromId, DateTime createdAt, bool isImported)
+        : base(id, chatId, senderId, replyToId, forwardedFromId, createdAt, isImported)
+    {
+        Content = question ?? "Poll";
+        if (options != null) foreach (var opt in options) Options.Add(new PollOption { Text = opt });
+        IsMultipleChoice = isMultiple;
+        ExpiresAt = expiresAt;
+    }
+}
+
+public class PollOption { public string Text { get; set; } = string.Empty; public int VoteCount { get; set; } }
+public class PollVote { public Guid OptionIndex { get; set; } public Guid UserId { get; set; } public DateTime VotedAt { get; set; } }

backend/src/Contracts/Messaging/Domain/MessageEvents.cs

@@ -0,0 +1,28 @@
+using Knot.Shared.Kernel;
+
+namespace Knot.Contracts.Messaging.Domain;
+
+/// <summary>
+/// Доменное событие: сообщение отправлено.
+/// </summary>
+public sealed record MessageSentDomainEvent(Guid MessageId, Guid ChatId, Guid SenderId, string? Content) : IDomainEvent;
+
+/// <summary>
+/// Доменное событие: сообщение удалено.
+/// </summary>
+public sealed record MessageDeletedDomainEvent(Guid MessageId, Guid ChatId) : IDomainEvent;
+
+/// <summary>
+/// Доменное событие: сообщение отредактировано.
+/// </summary>
+public sealed record MessageEditedDomainEvent(Guid MessageId, Guid ChatId, string NewContent) : IDomainEvent;
+
+/// <summary>
+/// Доменное событие: реакция добавлена.
+/// </summary>
+public sealed record MessageReactionAddedDomainEvent(Guid MessageId, Guid ChatId, Guid UserId, string Emoji) : IDomainEvent;
+
+/// <summary>
+/// Доменное событие: реакция удалена.
+/// </summary>
+public sealed record MessageReactionRemovedDomainEvent(Guid MessageId, Guid ChatId, Guid UserId, string Emoji) : IDomainEvent;

backend/src/Contracts/Messaging/Domain/MessageReaction.cs

@@ -0,0 +1,25 @@
+using System;
+using Knot.Shared.Kernel;
+
+namespace Knot.Contracts.Messaging.Domain;
+
+public sealed class MessageReaction : AggregateRoot<Guid>
+{
+    public Guid MessageId { get; private set; }
+    public Guid UserId { get; private set; }
+    public string Emoji { get; private set; }
+    public DateTime CreatedAt { get; private set; }
+
+    private MessageReaction() : base(Guid.Empty) 
+    {
+        Emoji = default!;
+    }
+
+    public MessageReaction(Guid messageId, Guid userId, string emoji) : base(Guid.NewGuid())
+    {
+        MessageId = messageId;
+        UserId = userId;
+        Emoji = emoji;
+        CreatedAt = DateTime.UtcNow;
+    }
+}

backend/src/Contracts/Messaging/Domain/MessageState.cs

@@ -0,0 +1,14 @@
+namespace Knot.Contracts.Messaging.Domain;
+
+/// <summary>
+/// Состояние сообщения
+/// </summary>
+[Flags]
+public enum MessageState
+{
+    None = 0,
+    IsEdited = 1,
+    IsDeleted = 2,
+    IsImported = 4,
+    IsPinned = 8
+}

backend/src/Contracts/Messaging/Domain/Reaction.cs

@@ -0,0 +1,23 @@
+using System;
+using Knot.Shared.Kernel;
+
+namespace Knot.Contracts.Messaging.Domain;
+
+public sealed class Reaction : Entity<Guid>
+{
+    public Guid MessageId { get; private set; }
+    public Guid UserId { get; private set; }
+    public string Emoji { get; private set; }
+
+    internal Reaction(Guid messageId, Guid userId, string emoji) : base(Guid.NewGuid())
+    {
+        MessageId = messageId;
+        UserId = userId;
+        Emoji = emoji;
+    }
+
+    private Reaction() : base(Guid.Empty)
+    {
+        Emoji = string.Empty;
+    }
+}

backend/src/Contracts/Settings/Domain/SystemSettingsUpdatedDomainEvent.cs

@@ -0,0 +1,8 @@
+using Knot.Shared.Kernel;
+
+namespace Knot.Contracts.Settings.Domain;
+
+/// <summary>
+/// Доменное событие: системные настройки обновлены.
+/// </summary>
+public sealed record SystemSettingsUpdatedDomainEvent(Application.DTOs.SystemSettingsDto Settings) : IDomainEvent;