Slack

Slack OAuth is workspace-scoped. One Connection = one workspace.

Connect

1. 1
   Open the picker

   Connections → Connect → Slack.

2. 2
   Pick workspace + approve

   Slack asks which workspace, then shows the scope list: channels:read, channels:history, chat:write, users:read, team:read.

   

3. 3
   Verify

   Back in Connections: workspace name shows, refresh token marked yes. Slack refreshes every 12h on Nomos's hourly sweep.

Commands

• /slack/channel/list, /slack/channel/info, /slack/channel/history
• /slack/message/post, /slack/message/reply, /slack/message/update, /slack/message/delete (step-up)
• /slack/user/list, /slack/user/get_by_email, /slack/user/info
• /slack/dm/open, /slack/reaction/add, /slack/reaction/remove
• /slack/pin/add, /slack/topic/set
• /slack/search/messages (admin-only)

Starter policies

• slack:read-only — channel listing, history, user lookup. No posts.
• slack:safe-default — read + post to channels matching a pattern. Delete requires step-up. Useful for a notification bot.
• slack:channel-pinned — narrow to one channel. Sandbox-friendly.

Cedar fragment

permit (
  principal,
  action in [Action::"/slack/channel/history", Action::"/slack/message/post"],
  resource
) when {
  resource.channel == "C0123ABC"  // only #ops
};

forbid (
  principal,
  action == Action::"/slack/message/delete",
  resource
) when { !context.cosigner };

Operational gotchas

• Bot can't post in a channel+

  Slack requires the bot to be invited to private channels. `/invite @nomos-bot` in the channel.
• Rate limits hit+

  Slack tier-2 rate limits (50 RPM per workspace). Nomos respects retry-after; your agent should not retry-on-deny.
• Want to attribute posts to a real user, not a bot+

  Use a user-token connection instead of bot-token. Re-connect via Slack with `user_scope=…` when prompted.