Groups

Group, channel, and forum conversations use the same message model as direct chats.

• type = "group" | "channel" | "forum"
• Creator is owner
• Additional users are member unless addParticipant specifies admin or moderator
• Only owners and admins can add participants
• Direct conversations cannot add participants

Mentions can be stored in metadata (for example { mentions: ["user-id"] }). There is no separate mention table; clients render them.

See community for threads and reactions, and retention for optional policy on create.