Channels & DMs

Channels are where topic-based conversations live. Direct messages (DMs) are the same plumbing scoped to specific people. They share the same storage, the same search index, and the same notification rules.

Channel types

Type	Visible to	Joinable by
Public	Everyone in the workspace (auto-listed).	Anyone, self-serve.
Private	Members only (hidden from the directory).	By invite only.
DM	Explicit participants only.	By creating a new DM.
Group DM	Up to 8 participants.	By creating a new group DM.

Creating a channel

Sidebar → + Add → New channel.

Name (alphanumeric + dashes, lowercased automatically).
Visibility (public or private).
Optional purpose and description.
Optional retention policy (see below).

Joining and leaving

Public channels: click Join from the channel directory (Cmd+K → "Browse channels").
Private channels: an existing member invites you.
Leaving: Channel menu → Leave channel. Your history is preserved; you just stop receiving notifications and lose access if the channel is private.

Members and guests

Channels distinguish between:

Members — full workspace users with the channel's default permissions.
Guests — invited to specific channels only. Can't see the rest of the workspace.

Guests are ideal for clients, contractors, or external vendors. Managed under Channel menu → Manage members.

Direct messages

DMs are found under the Direct messages section of the sidebar. Start a new one from Cmd+K → type a name → Enter.

Group DMs max out at 8 participants. Beyond that, create a private channel — it's the same data model without the member cap.

Message composition

Supported:

Markdown (bold, italic, strikethrough, code, blockquote)
Fenced code blocks with syntax highlighting
Emoji (:shortcode: or picker)
@-mentions (user, @here, @channel, @everyone)
File attachments (drag, paste, or click)
Rich link unfurls (shows preview of the linked page)
Polls via /poll slash command

Reactions and pins

Reactions: hover a message → smiley icon. Multiple users can stack on the same emoji with a count.

Pins: message menu → Pin to channel. Pinned messages show in the channel's Pinned tab — handy for the "welcome" post or an FAQ.

Archiving

Channel menu → Archive. Archived channels are read-only and hidden from the default sidebar. Members can still search them.

Unarchive anytime from Settings → Channels → Archived.

Retention policies

Per-channel retention is set under Channel menu → Settings → Retention. Options:

Keep everything (default)
Delete messages older than N days (30, 90, 180, 365)
Custom (admin-only)

The nightly comms-retention-sweeper Edge Function enforces policies. Deleted messages are soft-deleted for 7 days, then hard- deleted.

Keyboard shortcuts

Shortcut	Action
`Cmd+K`	Quick switcher.
`Cmd+Shift+A`	Mark all channels read.
`Cmd+Shift+U`	Jump to the next unread channel.
`Esc`	Close thread / dialog.
`↑` in empty composer	Edit your last message.
`T` in sidebar	Expand thread navigator.