Summary

When someone replies to the bot in a Slack thread, the bot's response goes to the channel root instead of staying in the thread.

Expected behavior

If incoming message has thread_ts, the auto-reply should use that as thread_ts to reply in-thread.

Current behavior

The ReplyToId is captured from message.thread_ts ?? message.ts in monitor.ts, but the auto-reply doesn't seem to use it when sending responses.

Steps to reproduce

1. Bot is in a Slack channel
2. User sends a message, bot replies (in channel root - fine)
3. User replies to bot's message in a thread
4. Bot responds in channel root instead of the thread