feat: Slack starter pack and profile

[dpup]

Summary

Ship a Slack profile and starter pack with rules targeting common agent-in-Slack risks: broadcast mentions, sensitive topics, DM spam, and channel scope.

Profile: profiles/slack.yaml

name: slack
aliases:
  channel: "params.channel"
  text: "params.text"
  thread: "params.thread_ts"
  recipient: "params.user"

Starter Pack: starter-packs/slack-safe-defaults.yaml

name: slack-safe-defaults
profile: slack
rules:
  - name: no-broadcast-mentions
    match:
      operation: "send_message"
      when: "text.matches('<!here>|<!channel>|<!everyone>')"
    action: deny
    message: "Broadcast mentions (@here, @channel, @everyone) are not permitted."

  - name: no-sensitive-topics
    match:
      operation: "send_message"
      when: >
        containsAny(text, ['acquisition', 'merger', 'LOI', 'term sheet',
                           'layoff', 'RIF', 'reorg'])
    action: deny
    message: "Message contains sensitive business terms. Send manually."

  - name: no-dm-spam
    match:
      operation: "send_message"
      when: >
        has(recipient)
        && rateCount('slack:dm:' + context.agent_id, '1h') > 20
    action: deny
    message: "DM rate limit exceeded. Maximum 20 direct messages per hour."

  - name: message-rate
    match:
      operation: "send_message"
      when: "rateCount('slack:msg:' + context.agent_id, '1h') > 60"
    action: deny
    message: "Message rate limit exceeded. Maximum 60 messages per hour."

  - name: audit-all
    match:
      operation: "*"
    action: log

Notes

• Slack token scopes already restrict channel access — Keep adds parameter-level filtering that tokens don't support (message content, mention patterns)
• Rate limits are conservative starting points; users override via pack overrides
• Include fixture tests covering: allow normal message, deny @here, deny sensitive topic, rate limit trigger