The Chat module provides multi-channel messaging with channels, members, threaded messages, mentions, read markers, and file attachments. It follows the same port/adapter pattern as other modules.

Endpoints

Endpoint	Method	Description
`/api/chat/channels`	POST	Create channel
`/api/chat/channels`	GET	List channels
`/api/chat/channels/{id}/members`	POST	Add member
`/api/chat/channels/{id}/messages`	POST	Send message
`/api/chat/channels/{id}/messages`	GET	Paginated messages
`/api/chat/channels/{id}/read`	POST	Mark as read
`/api/chat/messages/{id}`	PATCH	Edit message

Architecture

ChatEndpoints (Minimal API)
       │
       ▼
ChatService
       │
       ├── IChatRepository → SqlSugarChatRepository
       ├── IChatEventPublisher → NullChatEventPublisher
       ├── IChatRealtimeAdapter → NullChatRealtimeAdapter (roadmap: SignalR)
       └── IChatAttachmentAccessService → FileAssetChatAttachmentAccessService

Entities

Entity	Purpose
`ChatChannelEntity`	Channel definition (name, type, tenant)
`ChatMemberEntity`	Channel membership (user + role)
`ChatMessageEntity`	Messages (content, sender, edited flag)
`ChatAttachmentEntity`	Message file attachments
`ChatMentionEntity`	@mention tracking
`ChatReadMarkerEntity`	Per-user read position

Permissions

Chat uses attribute-based permissions via ChatPermissions:

public static class ChatPermissions
{
    public const string ChannelCreate = "chat.channel.create";
    public const string ChannelManage = "chat.channel.manage";
    public const string MessageSend = "chat.message.send";
    public const string MessageEdit = "chat.message.edit";
    public const string MemberManage = "chat.member.manage";
}

Message pagination

public class ChatMessagePage
{
    public IReadOnlyList<ChatMessage> Messages { get; }
    public int TotalCount { get; }
    public bool HasMore { get; }
}

Messages are loaded in reverse chronological order with cursor-based pagination.

Realtime adapter (roadmap)

public interface IChatRealtimeAdapter
{
    Task MessageCreatedAsync(ChatMessage message, CancellationToken ct);
    Task MessageEditedAsync(ChatMessage message, CancellationToken ct);
    Task MemberJoinedAsync(ChatMember member, CancellationToken ct);
}

Planned implementations: SignalR hub, Server-Sent Events, WebSocket adapter.