feat: add Slack channel adapter (Phase 3b)

Implement ChannelAdapter for Slack using @slack/bolt with Socket Mode:
- Thread-aware peer IDs (channelId:threadTs)
- Bot message and channel allowlist filtering
- Bot mention stripping (<@U\w+> pattern)
- Message chunking at 4000 chars for readability
- Error handling in connect/disconnect lifecycle
- Typed SlackMessageEvent interface
- 22 tests covering all behaviors
This commit is contained in:
William Valentin
2026-02-06 14:24:17 -08:00
parent 00db84f6a1
commit eeaec53893
3 changed files with 596 additions and 0 deletions
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import { describe, it, expect, vi, beforeEach } from 'vitest';
// ── Mock @slack/bolt before importing adapter ──────────────────────
let capturedMessageHandler: ((args: Record<string, unknown>) => Promise<void>) | null = null;
const mockPostMessage = vi.fn();
const mockStart = vi.fn();
const mockStop = vi.fn();
/** Create a fresh mock Bolt App instance. */
function createMockApp() {
capturedMessageHandler = null;
return {
message: vi.fn((handler: (args: Record<string, unknown>) => Promise<void>) => {
capturedMessageHandler = handler;
}),
start: mockStart,
stop: mockStop,
client: {
chat: {
postMessage: mockPostMessage,
},
},
};
}
let mockApp = createMockApp();
vi.mock('@slack/bolt', () => ({
App: vi.fn().mockImplementation(() => mockApp),
}));
import { SlackAdapter, type SlackAdapterConfig } from './adapter.js';
import type { InboundMessage } from '../types.js';
const baseConfig: SlackAdapterConfig = {
botToken: 'xoxb-test-token',
appToken: 'xapp-test-token',
signingSecret: 'test-signing-secret',
};
/** Helper: simulate a Slack message event through the captured handler. */
async function simulateMessage(message: Record<string, unknown>) {
if (!capturedMessageHandler) throw new Error('No message handler captured — call connect() first');
await capturedMessageHandler({ message });
}
describe('SlackAdapter', () => {
let adapter: SlackAdapter;
beforeEach(async () => {
vi.clearAllMocks();
mockApp = createMockApp();
// Re-wire the App mock to return the fresh mockApp
const { App } = vi.mocked(await import('@slack/bolt'));
(App as unknown as ReturnType<typeof vi.fn>).mockImplementation(() => mockApp);
adapter = new SlackAdapter(baseConfig);
});
// ── Basic properties ──────────────────────────────────────────
it('has name "slack"', () => {
expect(adapter.name).toBe('slack');
});
it('starts as disconnected', () => {
expect(adapter.status).toBe('disconnected');
});
// ── connect / disconnect ──────────────────────────────────────
it('connect creates Bolt App with Socket Mode and sets connected status', async () => {
await adapter.connect();
expect(adapter.status).toBe('connected');
const { App } = await import('@slack/bolt');
expect(App).toHaveBeenCalledWith({
token: 'xoxb-test-token',
appToken: 'xapp-test-token',
signingSecret: 'test-signing-secret',
socketMode: true,
});
expect(mockStart).toHaveBeenCalledTimes(1);
});
it('connect registers message handler via app.message()', async () => {
await adapter.connect();
expect(mockApp.message).toHaveBeenCalledTimes(1);
expect(capturedMessageHandler).toBeTypeOf('function');
});
it('disconnect stops app and sets disconnected', async () => {
await adapter.connect();
expect(adapter.status).toBe('connected');
await adapter.disconnect();
expect(mockStop).toHaveBeenCalledTimes(1);
expect(adapter.status).toBe('disconnected');
});
it('disconnect is safe when not connected', async () => {
await adapter.disconnect();
expect(adapter.status).toBe('disconnected');
// No app to stop — should not throw
});
// ── send ──────────────────────────────────────────────────────
it('send throws when not connected', async () => {
await expect(adapter.send('C123:1234.5678', { text: 'hello' })).rejects.toThrow(
'Slack adapter not connected',
);
});
it('send delivers a short message with correct channel and thread_ts', async () => {
await adapter.connect();
await adapter.send('C123:1234.5678', { text: 'Hello there' });
expect(mockPostMessage).toHaveBeenCalledTimes(1);
expect(mockPostMessage).toHaveBeenCalledWith({
channel: 'C123',
text: 'Hello there',
thread_ts: '1234.5678',
});
});
it('send chunks long messages (>4000 chars)', async () => {
await adapter.connect();
// Create a message longer than 4000 chars — two halves joined by a newline
const half = 'A'.repeat(3000);
const longMessage = `${half}\n${'B'.repeat(3000)}`;
await adapter.send('C123:1234.5678', { text: longMessage });
// Should have been split into at least 2 chunks
expect(mockPostMessage.mock.calls.length).toBeGreaterThanOrEqual(2);
// All calls should target the same channel and thread
for (const call of mockPostMessage.mock.calls) {
expect(call[0].channel).toBe('C123');
expect(call[0].thread_ts).toBe('1234.5678');
}
});
it('send throws on invalid peer ID format (no colon)', async () => {
await adapter.connect();
await expect(adapter.send('invalid-no-colon', { text: 'hello' })).rejects.toThrow(
'Invalid peer ID format: invalid-no-colon',
);
});
// ── onMessage / inbound handling ──────────────────────────────
it('inbound message triggers handler with correct peerId (channelId:threadTs)', async () => {
const handler = vi.fn();
adapter.onMessage(handler);
await adapter.connect();
await simulateMessage({
ts: '1234.5678',
thread_ts: '1111.0000',
channel: 'C123',
user: 'U456',
text: 'Hello Flynn',
});
expect(handler).toHaveBeenCalledTimes(1);
const msg: InboundMessage = handler.mock.calls[0][0];
expect(msg.channel).toBe('slack');
expect(msg.senderId).toBe('C123:1111.0000');
expect(msg.senderName).toBe('U456');
expect(msg.text).toBe('Hello Flynn');
expect(msg.id).toBe('1234.5678');
});
it('inbound message uses thread_ts for peer ID when in thread', async () => {
const handler = vi.fn();
adapter.onMessage(handler);
await adapter.connect();
await simulateMessage({
ts: '2222.3333',
thread_ts: '1111.0000',
channel: 'C123',
user: 'U456',
text: 'Threaded reply',
});
const msg: InboundMessage = handler.mock.calls[0][0];
expect(msg.senderId).toBe('C123:1111.0000');
});
it('inbound message falls back to ts when no thread_ts', async () => {
const handler = vi.fn();
adapter.onMessage(handler);
await adapter.connect();
await simulateMessage({
ts: '2222.3333',
channel: 'C123',
user: 'U456',
text: 'Top-level message',
});
const msg: InboundMessage = handler.mock.calls[0][0];
expect(msg.senderId).toBe('C123:2222.3333');
});
it('ignores bot messages (bot_id present)', async () => {
const handler = vi.fn();
adapter.onMessage(handler);
await adapter.connect();
await simulateMessage({
ts: '1234.5678',
channel: 'C123',
user: 'U456',
text: 'Bot message',
bot_id: 'B789',
});
expect(handler).not.toHaveBeenCalled();
});
it('ignores bot messages (subtype === "bot_message")', async () => {
const handler = vi.fn();
adapter.onMessage(handler);
await adapter.connect();
await simulateMessage({
ts: '1234.5678',
channel: 'C123',
user: 'U456',
text: 'Bot message',
subtype: 'bot_message',
});
expect(handler).not.toHaveBeenCalled();
});
it('ignores messages in disallowed channels', async () => {
const restrictedAdapter = new SlackAdapter({
...baseConfig,
allowedChannelIds: ['C-allowed'],
});
const handler = vi.fn();
restrictedAdapter.onMessage(handler);
await restrictedAdapter.connect();
await simulateMessage({
ts: '1234.5678',
channel: 'C-not-allowed',
user: 'U456',
text: 'Hello',
});
expect(handler).not.toHaveBeenCalled();
});
it('strips bot mentions (<@U\\w+> pattern)', async () => {
const handler = vi.fn();
adapter.onMessage(handler);
await adapter.connect();
await simulateMessage({
ts: '1234.5678',
channel: 'C123',
user: 'U456',
text: '<@UBOT123> What is the weather?',
});
expect(handler).toHaveBeenCalledTimes(1);
const msg: InboundMessage = handler.mock.calls[0][0];
expect(msg.text).toBe('What is the weather?');
});
it('!reset command delivers reset metadata', async () => {
const handler = vi.fn();
adapter.onMessage(handler);
await adapter.connect();
await simulateMessage({
ts: '1234.5678',
channel: 'C123',
user: 'U456',
text: '!reset',
});
expect(handler).toHaveBeenCalledTimes(1);
const msg: InboundMessage = handler.mock.calls[0][0];
expect(msg.text).toBe('!reset');
expect(msg.metadata).toEqual({ isCommand: true, command: 'reset' });
});
it('"reset" text (without !) delivers reset metadata', async () => {
const handler = vi.fn();
adapter.onMessage(handler);
await adapter.connect();
await simulateMessage({
ts: '1234.5678',
channel: 'C123',
user: 'U456',
text: 'reset',
});
expect(handler).toHaveBeenCalledTimes(1);
const msg: InboundMessage = handler.mock.calls[0][0];
expect(msg.text).toBe('!reset');
expect(msg.metadata).toEqual({ isCommand: true, command: 'reset' });
});
it('does nothing when no message handler is registered', async () => {
// Don't call onMessage — no handler registered
await adapter.connect();
// Should not throw
await simulateMessage({
ts: '1234.5678',
channel: 'C123',
user: 'U456',
text: 'Hello',
});
});
it('messages with no text property are handled (empty string)', async () => {
const handler = vi.fn();
adapter.onMessage(handler);
await adapter.connect();
await simulateMessage({
ts: '1234.5678',
channel: 'C123',
user: 'U456',
// no text property
});
expect(handler).toHaveBeenCalledTimes(1);
const msg: InboundMessage = handler.mock.calls[0][0];
expect(msg.text).toBe('');
});
it('allowed channel messages pass through when allowedChannelIds configured', async () => {
const restrictedAdapter = new SlackAdapter({
...baseConfig,
allowedChannelIds: ['C-allowed'],
});
const handler = vi.fn();
restrictedAdapter.onMessage(handler);
await restrictedAdapter.connect();
await simulateMessage({
ts: '1234.5678',
channel: 'C-allowed',
user: 'U456',
text: 'Hello',
});
expect(handler).toHaveBeenCalledTimes(1);
const msg: InboundMessage = handler.mock.calls[0][0];
expect(msg.text).toBe('Hello');
});
});
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/**
* Slack channel adapter.
*
* Implements the ChannelAdapter interface using @slack/bolt with Socket Mode.
* Thread-aware: each channel+thread gets its own session via channelId:threadTs peer IDs.
* Messages are chunked at 4000 chars for readability.
*/
import { App } from '@slack/bolt';
import type {
InboundMessage,
OutboundMessage,
ChannelAdapter,
ChannelStatus,
} from '../types.js';
/** Configuration for the Slack channel adapter. */
export interface SlackAdapterConfig {
botToken: string;
appToken: string;
signingSecret: string;
/** Channel IDs to respond in. Empty = all channels. */
allowedChannelIds?: string[];
}
/** Minimal shape of a Slack message event from Bolt. */
interface SlackMessageEvent {
ts?: string;
thread_ts?: string;
channel?: string;
user?: string;
text?: string;
bot_id?: string;
subtype?: string;
}
/**
* Split a long message into chunks that respect Slack's readability limit.
* Prefers splitting at newlines, then spaces, then hard-cuts.
*/
function splitMessage(text: string, maxLength: number): string[] {
const chunks: string[] = [];
let remaining = text;
while (remaining.length > 0) {
if (remaining.length <= maxLength) {
chunks.push(remaining);
break;
}
// Try to split at a newline within the allowed window
let splitIndex = remaining.lastIndexOf('\n', maxLength);
if (splitIndex === -1 || splitIndex < maxLength / 2) {
splitIndex = remaining.lastIndexOf(' ', maxLength);
}
if (splitIndex === -1 || splitIndex < maxLength / 2) {
splitIndex = maxLength;
}
chunks.push(remaining.slice(0, splitIndex));
remaining = remaining.slice(splitIndex).trimStart();
}
return chunks;
}
/**
* Slack channel adapter backed by @slack/bolt.
*
* Handles channel filtering, thread-aware peer IDs,
* and message chunking for readability (4000 chars).
*/
export class SlackAdapter implements ChannelAdapter {
readonly name = 'slack';
private _status: ChannelStatus = 'disconnected';
private app: App | null = null;
private messageHandler?: (msg: InboundMessage) => void;
private config: SlackAdapterConfig;
get status(): ChannelStatus {
return this._status;
}
constructor(config: SlackAdapterConfig) {
this.config = config;
}
/** Register the inbound message handler. Called by the registry before connect(). */
onMessage(handler: (msg: InboundMessage) => void): void {
this.messageHandler = handler;
}
/** Create the Bolt app with Socket Mode, wire up event handlers, and start. */
async connect(): Promise<void> {
this._status = 'connecting';
try {
this.app = new App({
token: this.config.botToken,
appToken: this.config.appToken,
signingSecret: this.config.signingSecret,
socketMode: true,
});
// Register message event handler
this.app.message(async ({ message }) => {
this.handleMessage(message as unknown as SlackMessageEvent);
});
await this.app.start();
this._status = 'connected';
console.log('Slack bot connected via Socket Mode');
} catch (error) {
this._status = 'error';
throw error;
}
}
/** Stop the Bolt app and clean up. */
async disconnect(): Promise<void> {
if (this.app) {
try {
await this.app.stop();
} finally {
this.app = null;
}
}
this._status = 'disconnected';
}
/** Send an outbound message, automatically chunking if it exceeds 4000 chars. */
async send(peerId: string, message: OutboundMessage): Promise<void> {
if (!this.app) throw new Error('Slack adapter not connected');
// Parse peerId: "channelId:threadTs"
const colonIndex = peerId.indexOf(':');
if (colonIndex === -1) throw new Error(`Invalid peer ID format: ${peerId}`);
const channel = peerId.slice(0, colonIndex);
const threadTs = peerId.slice(colonIndex + 1);
if (!channel || !threadTs) throw new Error(`Invalid peer ID format: ${peerId}`);
const text = message.text;
if (text.length <= 4000) {
await this.app.client.chat.postMessage({
channel,
text,
thread_ts: threadTs,
});
} else {
const chunks = splitMessage(text, 4000);
for (const chunk of chunks) {
await this.app.client.chat.postMessage({
channel,
text: chunk,
thread_ts: threadTs,
});
}
}
}
/** Internal: process an inbound Slack message event. */
private handleMessage(message: SlackMessageEvent): void {
if (!this.messageHandler) return;
// Ignore bot messages
if (message.bot_id || message.subtype === 'bot_message') return;
const channelId = message.channel;
if (!channelId) return;
// Check allowed channel IDs
if (
this.config.allowedChannelIds &&
this.config.allowedChannelIds.length > 0 &&
!this.config.allowedChannelIds.includes(channelId)
) {
return;
}
// Build peer ID: channelId:threadTs (thread-aware)
const threadTs = message.thread_ts ?? message.ts ?? '';
const peerId = `${channelId}:${threadTs}`;
// Strip bot mentions: <@U\w+> pattern
let text = (message.text ?? '').replace(/<@U\w+>/g, '').trim();
// TODO: message.user is a Slack user ID (e.g. U0123ABC), not a display name.
// To resolve display names, use this.app.client.users.info() with caching.
const senderName = message.user;
// Detect reset command
if (text === '!reset' || text === 'reset') {
this.messageHandler({
id: message.ts ?? '',
channel: 'slack',
senderId: peerId,
senderName,
text: '!reset',
timestamp: Date.now(),
metadata: { isCommand: true, command: 'reset' },
});
return;
}
// Regular message
this.messageHandler({
id: message.ts ?? '',
channel: 'slack',
senderId: peerId,
senderName,
text,
timestamp: Date.now(),
});
}
}
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export { SlackAdapter, type SlackAdapterConfig } from './adapter.js';