Group DMs (MPIMs) were classified as DMs and thereby exempted from every
operator control that shared surfaces are supposed to honor: allowed_channels,
require_mention, strict_mention, free_response_channels, and the reaction
guard. Symptom: the bot added 👀/✅ to unmentioned MPIM
messages and still invoked the agent (which then returned NO_REPLY) instead of
the gateway dropping the event before model execution. Removing an MPIM from
allowed_channels did not disable it.
Root cause is the DM classification at adapter.py:
is_dm = channel_type in {"im", "mpim"}
used for BOTH routing exemptions and reaction gating. An MPIM is a shared
surface (multiple humans can see and trigger the bot), not a private 1:1 DM,
so it must be gated like a channel.
This behavior was introduced/reinforced by a trail of Slack group-DM PRs:
- #4633 fix(slack): treat group DMs (mpim) like DMs + reaction guard
- #54632 fix(slack): subscribe to message.mpim + mpim scopes so group DMs work
- #54663 fix(slack): group DMs work OOTB + reinstall nudge
#54632/#54663 correctly made MPIM messages *reachable*; #4633 over-reached by
giving them the DM mention/reaction *exemptions*. This corrects only that
over-reach.
Fix (minimal): introduce `is_one_to_one_dm = channel_type == "im"` and key the
two EXEMPTION sites off it instead of `is_dm`:
- mention/allowlist gating block (`if not is_one_to_one_dm and bot_uid:`)
- reaction guard (`(is_one_to_one_dm or is_mentioned)`)
`is_dm` is intentionally retained for session/thread scoping and chat_type
labeling, where treating an MPIM as a persistent multi-party conversation is
correct — only the mention/reaction exemptions were wrong.
Docs: slack.md now distinguishes 1:1 DMs (mention-exempt) from group DMs
(shared surface; obey require_mention/strict_mention/allowed_channels/
free_response_channels; reactions only when @mentioned).
Tests: +7 in test_slack_mention.py (MPIM unmentioned dropped under
require_mention and strict_mention; MPIM mentioned processed; MPIM off
allowed_channels dropped; MPIM in free_response opted in; 1:1 IM still exempt;
reaction guard drops unmentioned MPIM). Updated _would_process to model the
is_one_to_one_dm gating + strict_mention. 72 passed.
accd672054