feat: add group chat and mention-gating to channel adapters

Slack: add requireMention option, resolve bot user ID on connect.
Telegram: add group chat mention/reply-to-bot detection, strip @mention
from message text, default requireMention=true for groups.
WhatsApp: add allowedGroupIds for group chat support, mention detection
via mentionedIds and body text, strip bot mention from messages.

src/channels/telegram/adapter.ts

@@ -15,6 +15,8 @@ import { splitMessage } from '../utils.js';
 export interface TelegramAdapterConfig {
   botToken: string;
   allowedChatIds: number[];
+  /** Require bot mention or reply-to-bot to respond in group chats (default: true). */
+  requireMention?: boolean;
   hookEngine?: HookEngine;
 }
 
@@ -32,6 +34,7 @@ export class TelegramAdapter implements ChannelAdapter {
   private bot: Bot | null = null;
   private messageHandler?: (msg: InboundMessage) => void;
   private config: TelegramAdapterConfig;
+  private botInfo?: { id: number; username?: string };
 
   get status(): ChannelStatus {
     return this._status;
@@ -120,7 +123,33 @@ export class TelegramAdapter implements ChannelAdapter {
     this.bot.on('message:text', async (ctx) => {
       if (!this.messageHandler) return;
 
-      const text = ctx.message.text;
+      // Group chat mention gating
+      const isGroup = ctx.chat.type === 'group' || ctx.chat.type === 'supergroup';
+      const requireMention = this.config.requireMention ?? true;
+
+      if (isGroup && requireMention && this.botInfo) {
+        const rawText = ctx.message.text;
+        const username = this.botInfo.username;
+
+        // Check for @bot_username mention
+        const isMentioned = username
+          ? rawText.includes(`@${username}`)
+          : false;
+
+        // Also allow replies to bot messages
+        const isReplyToBot = ctx.message.reply_to_message?.from?.id === this.botInfo.id;
+
+        if (!isMentioned && !isReplyToBot) {
+          return;
+        }
+      }
+
+      let text = ctx.message.text;
+
+      // Strip bot mention from text
+      if (isGroup && this.botInfo?.username) {
+        text = text.replace(new RegExp(`@${this.botInfo.username}\\b`, 'g'), '').trim();
+      }
 
       // Show typing indicator while processing
       await ctx.replyWithChatAction('typing');
@@ -140,6 +169,7 @@ export class TelegramAdapter implements ChannelAdapter {
     this.bot.start({
       onStart: (botInfo) => {
         console.log(`Telegram bot started: @${botInfo.username}`);
+        this.botInfo = { id: botInfo.id, username: botInfo.username };
         this._status = 'connected';
       },
     });