@memberjunction/ai-bridge-slack

The Slack huddle Realtime Bridge driver in MemberJunction's Realtime Bridges program. It connects the one realtime agent engine to a Slack huddle: bidirectional audio (and directional video + screen, since modern huddles do full AV), a diarized participant roster, participant mute, huddle/thread chat, and a Meeting Controls facilitator channel — all behind an injectable Slack huddle SDK seam so the driver builds and unit-tests with no network and no real Slack / Chime SDK. It is a structural mirror of the reference @memberjunction/ai-bridge-zoom driver.

See the Realtime Bridges Guide and /plans/realtime/realtime-bridges-architecture.md (§3 provider abstraction, §4b channels, §8 Slack capability row) for the full architecture.

🚨 REAL-API RISK — the huddle MEDIA API is the gating unknown 🚨

This is the one Realtime Bridge driver with a genuine API-availability risk, not merely a binding TODO.

Unlike Zoom and Teams — where binding the real SDK is a known, documented deployment step — Slack does not publicly document a supported bot-join-with-media path for huddles. There is no published way for an app/bot to join a huddle as a media participant and pull per-participant PCM audio / push synthesized audio back. Because huddles run on Amazon Chime under the hood, production media access may require a Chime-level integration (a Chime SDK media pipeline / app instance) and/or an entitlement Slack does not expose through its standard developer surface.

What this means:

• On firm public-API ground (signaling + chat): huddle membership/roster, huddle start/end events, chat.postMessage, and participant mute. The driver's roster, chat, and Meeting-Controls perception for these work against documented Slack Web API + Events/Socket Mode surfaces.
• At risk (media): audio in/out and diarized speaking — these depend on the unverified huddle media path.

The driver and its ISlackHuddleSdk seam are deliberately built as if the media path exists, so the moment huddle media access is verified/obtained, binding it is a thin adapter with no driver changes. But the provider must stay Disabled until someone confirms a supported bot-join-with-media path (or stands up the Chime-level pipeline). The risk is flagged in three places in code: the ISlackHuddleSdk seam header (slack-sdk.ts), the SlackBridge class doc (slack-bridge.ts), and a // REAL-API RISK: comment on the default (unbound) SDK factory whose thrown error names the huddle-media requirement.

Install

npm install @memberjunction/ai-bridge-slack

What it provides

• SlackBridge — @RegisterClass(BaseRealtimeBridge, 'SlackBridge'). The MJ: AI Bridge Providers row with DriverClass = 'SlackBridge' resolves to this driver via the ClassFactory. Implements the four BaseRealtimeBridge abstracts (Connect / Disconnect / SendMedia / OnMedia) and the capability-gated virtuals Slack supports (GetParticipants, OnParticipantChange), plus GetMeetingControlsEventSource for the facilitator channel and a PostChatMessage helper.
• ISlackHuddleSdk — the injectable seam the driver depends on instead of the real SDK, named after Slack huddle concepts. See the REAL-API RISK above — its media operations are the gating unknown.
• SlackMeetingControlsEventSource — adapts the seam's roster / hand-raise / speaking / mute into the bridge's IBridgeMeetingControlsEventSource, so the engine wires the Meeting Controls channel.

Capability coverage (the Slack seed row)

| Capability | Status | |---|---| | On-demand + scheduled + invite join | ✅ (invite ⚠️ per the seed) | | Inbound routing | ⚠️ advertised; subject to the same huddle-access caveats | | Audio in / out | ✅ at the seam — ⚠️ depends on the gating-unknown huddle media path | | Video in/out, Screen in/out (directional flags) | ✅ (transport carries them; models light audio first — ⚠️ media path) | | Speaker diarization (roster + per-speaker labels) | ✅ at the seam — ⚠️ per-speaker audio depends on the huddle media path | | Participant mute (Meeting Controls) | ✅ | | Huddle / thread chat | ✅ | | Native raised-hand | ⚠️ Partial — wired where Slack surfaces it to apps; tolerant of it never firing | | DTMF / call transfer / recording | ➖ not Slack-huddle features here — the gated base methods throw BridgeCapabilityNotSupportedError |

Capability gating is two-layer (defense-in-depth): the engine checks the provider's SupportedFeatures first, and the driver re-asserts each flag with RequireFeature at the top of its overrides.

Slack vs. Zoom capability differences

Slack advertises everything Zoom does, plus InviteJoin and InboundRouting (⚠️ in the seed). It does not advertise NativeInvite (unlike Teams). The decisive difference, however, is not a capability flag but the media-API availability risk above: Zoom's media binding is a documented deployment TODO, whereas Slack's huddle media binding is genuinely unverified.

The Slack huddle SDK seam (ISlackHuddleSdk)

The driver never imports the real Slack / Chime SDK. It depends only on this minimal interface, named after Slack huddle concepts (huddles do full audio + video + screen and run on Amazon Chime under the hood):

export interface ISlackHuddleSdk {
    join(args: SlackJoinArgs): Promise<SlackJoinResult>;
    leave(): Promise<void>;
    sendAudioFrame(pcm: ArrayBuffer): void;                                 // ⚠️ agent's voice out — huddle media path (Chime)
    onAudioFrame(cb: (frame: SlackAudioFrame) => void): void;               // ⚠️ raw per-participant audio in — huddle media path
    onParticipantJoin(cb: (p: SlackParticipant) => void): void;
    onParticipantLeave(cb: (id: string) => void): void;
    onHandRaise(cb: (id: string, raised: boolean) => void): void;           // ⚠️ partial on Slack
    getParticipants(): Promise<SlackParticipant[]>;
    postChatMessage(text: string): Promise<void>;                           // huddle / thread chat
    muteParticipant(participantId: string): Promise<void>;
    onMeetingEnded(cb: () => void): void;
}

Production binding (deployment — gated on the REAL-API RISK above)

In production this is bound to a thin adapter over the Slack Web API + Events/Socket Mode (membership, roster events, chat, mute) plus a verified huddle media path (likely an Amazon Chime-level integration) for per-participant PCM audio in/out. Supply a factory via the creation seam:

import { SlackBridge } from '@memberjunction/ai-bridge-slack';

// Once, where bridge drivers are configured:
//   bridge.SetSdkFactory((config) => new RealSlackHuddleSdkAdapter(config));
// The adapter implements ISlackHuddleSdk over the real Slack SDK + a verified huddle media path.
// The driver + its tests do not change.

Out of the box, SlackBridge ships without the real SDK adapter — Connect throws an explicit "bind the real Slack huddle SDK … plus a verified huddle MEDIA path" error until SetSdkFactory is called. Tests inject a FakeSlackHuddleSdk. Do not promote the provider from Disabled until the huddle media path is verified/obtained (see the REAL-API RISK section).

Usage (engine-driven)

The bridge is not used directly — AIBridgeEngine.StartBridgeSession (@memberjunction/ai-bridge-server) resolves it from the provider's DriverClass, wires the transport seam to the injected IRealtimeSession, and (when a channel host is supplied) wires the Meeting Controls channel from GetMeetingControlsEventSource. See the bridge-server package and the guide's "Channel plane" section.

Testing

FakeSlackHuddleSdk (in src/__tests__/) is an in-memory ISlackHuddleSdk with drive helpers and capture sinks — it stands in for the gating-unknown huddle media path so the driver can be fully exercised today, ahead of any verified production media binding. The suite covers connect/disconnect (incl. parsing the channel id out of the huddle link and the explicit huddle-media error when no SDK is bound), audio in→OnMedia (speaker labels) and out→seam, participant join/leave → roster + event source, native hand-raise → Meeting Controls perception, capability gating (a feature Slack lacks throws; the Slack feature set propagates), and chat — all with no network.

cd packages/AI/Providers/BridgeSlack && npm run test