slack-a2a-rooms skill

Slack agent-to-agent rooms (SLACKA2AROOMS)

Lets two or more NanoClaw Slack bots talk to each other — and to a human — in a shared group DM (MPIM). Empirically established against live Slack: conversations.open with users=[, …] works from a bot token holding mpim:write and returns an ismpim channel, and bots receive each other's messages over their own Socket Mode connections as plain message events with channeltype: "mpim", bot_id set, and subtype null.

Canonical home. This directory on main is the skill's canonical source — the setup wizard and any direct apply read it from the checkout. The copy on the channels branch is a compatibility mirror for older checkouts whose setup fetches companions from there; edits land here, never there.

Where sibling-bot messages die today. The adapter/Chat-SDK stack's only bot filter is self-protection (isMe); a sibling bot's message arrives with isMe: false, isBot: true and flows into the Slack channel's bot-inbound guard (src/channels/slack-a2a-guard.ts, installed with /add-slack), which drops all bot-authored inbound at the bridge boundary by default — before the router, before any sender-approval flow. The guard exposes a single admission seam, setBotInboundPolicy; this skill registers the policy that opens it up selectively:

to the user id slack:bot:, under a consecutive-hop limit.

• Rooms listed in SLACKA2AROOMS: bot-authored inbound passes, attributed

as the guard's default already does.

• Everywhere else: bot-authored inbound stays dropped at the bridge, exactly

Loop safety. After N consecutive bot-authored inbound messages in an A2A room without a human message (N = SLACKA2AMAX_HOPS, default 6), further bot messages are dropped with a log line until a human speaks. The counter is per bot identity and per room; any human message resets it.

Requires:

bot-inbound guard (src/channels/slack-a2a-guard.ts with the setBotInboundPolicy seam). The default drop arrives with that payload; this skill only adds the allowlisted-room admission on top.

• The Slack channel installed (/add-slack), current enough to ship the

hosts sharing the workspace). Named identities are registered natively by the adapter from SLACKINSTANCES — see the slack-multi-instance skill for the env-key format. scripts/open-a2a-room.ts reads tokens by that convention (SLACKBOTTOKEN; default → SLACKBOTTOKEN).

• At least two Slack bot identities on this host (or sibling bots on other

mpim:write (open the room), mpim:history + mpim:read (see it), and the message.mpim bot event (hear it). Apps provisioned through the managed flow (apps.manifest.create + apps.managedInstall) already include all of these.

• Every participating app's manifest must carry the MPIM scopes and event:

Apply

1. Verify the installed Slack channel ships the bot-inbound guard

The policy module copied next imports setBotInboundPolicy from the installed src/channels/slack-a2a-guard.ts. On a Slack payload that predates the guard, that import takes down the channel barrel — and with it every adapter — so verify the seam first. If the check fails, stop: re-run /add-slack from a channels branch that ships the guard, then re-apply this skill.

grep -sq 'export function setBotInboundPolicy' src/channels/slack-a2a-guard.ts || { echo 'slack-a2a-rooms: src/channels/slack-a2a-guard.ts is missing or does not export setBotInboundPolicy. Installing anyway would break the channel barrel and take down every channel adapter. Update the installed Slack channel first (re-run /add-slack from a channels branch that ships the bot-inbound guard), then re-apply this skill.' >&2; exit 1; }

2. Copy the policy module, its guard test, and the room-opener script

This skill ships three files alongside this document; copy them into the tree at the same relative paths (overwrite; the skill's copies are canonical):

src/channels/slack-a2a.ts
src/channels/slack-a2a.test.ts
scripts/open-a2a-room.ts

SLACKA2AMAX_HOPS parsing (re-read with a ~30s cache so a freshly opened room needs no restart), the per-room, per-identity consecutive-hop counter with human reset, and the slack:bot: re-attribution. The module registers itself onto the guard's admission seam on import.

• slack-a2a.ts — the admission policy: SLACKA2AROOMS /

real bot-inbound guard end-to-end (see step 4 for what it pins).

• slack-a2a.test.ts — the guard: drives the real channel barrel and the

• open-a2a-room.ts — operator CLI to open a room (see Configuration).

3. Register the policy module

Append the self-registration import to the channel barrel (skipped if the line is already present). Appending at the end keeps it after the Slack channel's own imports:

import './slack-a2a.js';

4. Build and validate

Build first — it guards the typed setBotInboundPolicy call against guard drift. The test imports the real channel barrel (a deleted or broken barrel line goes red) and asserts the policy end-to-end: allowlisted-room admission with slack:bot: re-attribution, non-listed-room drop, the hop limit with human reset, per-room/per-identity budgets, and that a downstream throw consumes no hop budget:

pnpm run build

pnpm exec vitest run src/channels/slack-a2a.test.ts

Configuration

.env keys (both re-read with a ~30s cache — no restart needed after edits):

opener script prints, e.g. G0AAAAAAA — note MPIM ids may start with G or C depending on workspace vintage). Only these rooms admit bot-authored inbound.

• SLACKA2AROOMS — comma-separated raw Slack channel ids (the MPIM ids the

an A2A room without a human message before further bot messages are dropped. Default 6.

• SLACKA2AMAX_HOPS — consecutive bot-authored inbound messages allowed in

Opening a room

pnpm exec tsx scripts/open-a2a-room.ts --instances dana,eli --user U0AAAAAAA

The first listed instance opens the conversation (via conversations.open with the human + the other bots' user ids, resolved through auth.test per token) and posts an intro message. The script prints the channel id and appends it to SLACKA2AROOMS in .env. Without --user you get a bots-only room, which needs at least three instances (Slack collapses a two-party open into a 1:1 IM).

Letting bot senders through the access gate

The room allowlist gets bot messages to the router; the permissions module still gates them like any sender. Bot senders arrive as user id slack:bot:, which starts unknown. After the first human mention in the room auto-creates its messaging group, either set the room public:

pnpm exec tsx scripts/q.ts data/v2.db "UPDATE messaging_groups SET unknown_sender_policy='public' WHERE platform_id='slack:<channel id>'"

or keep request_approval and approve each slack:bot: sender once (or add them as members of the agent group). A private A2A room with known humans is a reasonable place for public.

Engagement: A2A conversation is mention-driven

An MPIM is a group context in NanoClaw's channel-defaults model (Slack DMs are only D… channels), so the Slack group defaults apply: engagemode: mention-sticky, per-thread stickiness. That means a bot replies when it is @-mentioned (then stays engaged in that thread) — it does not answer every room message. Bot-to-bot conversation is therefore mention-driven by design: bot A's reply reaches bot B's agent when it @-mentions bot B, and the chain continues only as long as each reply mentions the next speaker. Slack does not emit appmention for bot-authored messages, but mention detection still works: the Chat SDK's text-level detector matches the bot's own <@U…> token, which the adapter deliberately leaves unresolved in the text. This is the intended loop governor alongside the hop limit — prompt the agents (group CLAUDE.md / personality) to @-mention the sibling they want an answer from, and to stop mentioning anyone when the exchange has converged.

Remove

src/channels/slack-a2a.test.ts, scripts/open-a2a-room.ts.

1. Delete the three copied files: src/channels/slack-a2a.ts,

unknownsenderpolicy='public', and archive/leave the MPIMs from Slack (the rooms themselves are ordinary Slack conversations; NanoClaw holds no other state for them beyond the usual messaging-group/session rows).

1. Delete the import './slack-a2a.js'; line from src/channels/index.ts.
2. Remove SLACKA2AROOMS and SLACKA2AMAX_HOPS from .env.
3. Optionally re-tighten any messaging groups you set to

1. Rebuild (pnpm run build).

With the skill removed, the channel guard's default applies everywhere again: bot-authored inbound is dropped in every room.

Notes

drops bot-authored messages in rooms not listed in SLACKA2AROOMS at the bridge — before the router and before any sender-approval flow — with or without this skill applied. If an install relies on a bot sender (another workspace app posting into a channel the agent watches), add that room to SLACKA2AROOMS. Human messages are never affected.

• Bot senders outside A2A rooms: the Slack channel's bot-inbound guard