fix: remove slack new chat message

.changeset/bright-garlics-lick.md

@@ -0,0 +1,6 @@
+---
+'slack-example': patch
+'@callstack/byorg-slack': patch
+---
+
+Added useful plugins for normalizing threads (Slack started adding "New chat" message). Updated example slack app.

examples/slack/src/index.ts

@@ -1,7 +1,7 @@
 import { VercelChatModelAdapter, createApp } from '@callstack/byorg-core';
 import { createOpenAI } from '@ai-sdk/openai';
 import { logger, requireEnv } from '@callstack/byorg-utils';
-import { createSlackApp } from '@callstack/byorg-slack';
+import { createSlackApp, slackThreadNormalizerPlugin } from '@callstack/byorg-slack';
 
 const LANGUAGE_MODEL = 'gpt-4o-2024-11-20';
 const API_KEY = requireEnv('OPENAI_API_KEY');
@@ -27,6 +27,7 @@ const SYSTEM_PROMPT = 'Your name is Byorg. You are a helpful AI Assistant.';
 const app = createApp({
   chatModel,
   systemPrompt: SYSTEM_PROMPT,
+  plugins: [slackThreadNormalizerPlugin],
 });
 
 const slack = createSlackApp({

packages/slack/src/__tests__/plugins.test.ts

@@ -0,0 +1,24 @@
+import { createApp, createMockChatModel, Message } from '@callstack/byorg-core';
+import { describe, expect, it, vitest } from 'vitest';
+import { slackThreadNormalizerPlugin } from '../plugins/thread-normalization.js';
+
+describe('threadNormalizer', () => {
+  it('should remove slack "New chat" initial message', async () => {
+    const messages: Message[] = [
+      { role: 'user', content: 'New chat\n' },
+      { role: 'user', content: 'Hello!' },
+    ];
+    const baseModel = createMockChatModel({ delay: 0, seed: 3 });
+
+    const modelSpy = vitest.spyOn(baseModel, 'generateResponse');
+
+    const app = createApp({
+      chatModel: baseModel,
+      plugins: [slackThreadNormalizerPlugin],
+    });
+
+    await app.processMessages(messages);
+
+    expect(modelSpy.mock.calls[0][0]['messages']).toEqual([{ role: 'user', content: 'Hello!' }]);
+  });
+});

packages/slack/src/index.ts

@@ -6,3 +6,4 @@ export {
   slackEntityResolverPlugin,
   extractUserMentionsFromMessage,
 } from './plugins/entity-resolver.js';
+export { slackThreadNormalizerPlugin } from './plugins/thread-normalization.js';

packages/slack/src/plugins/thread-normalization.ts

@@ -0,0 +1,20 @@
+import { ApplicationPlugin, MessageResponse } from '@callstack/byorg-core';
+import { logger } from '@callstack/byorg-utils';
+
+/**
+ * Slack plugin for normalizing messages coming from Slack [AI apps](https://api.slack.com/docs/apps/ai). 
+ */
+export const slackThreadNormalizerPlugin: ApplicationPlugin = {
+  name: 'slack-thread-normalizer',
+  middleware: async (context, next): Promise<MessageResponse> => {
+    const { messages } = context;
+
+    if (messages[0].content === 'New chat\n' && messages[1]?.role === 'user') {
+      context.messages = messages.slice(1);
+      logger.debug('Removed Slack "New Chat" message');
+    }
+
+    // Continue middleware chain
+    return await next();
+  },
+};