assistant_thread_started not fired when user clicks "+" to open a new thread from history in an already-open assistant container

[anton-chernov-nrich]

Summary

When a user opens a new assistant thread for the first time, assistant_thread_started fires correctly. However, if the user already has an existing conversation, opens the history panel, and clicks "+" to create a new thread, no event fires at all — not assistant_thread_started, not assistant_thread_context_changed, nothing. The thread shows "Waiting for [Bot] to start a conversation…" permanently and the user cannot type.

Steps to Reproduce

1. User opens the assistant DM → assistant_thread_started fires, bot sends greeting ✓
2. User sends a message → bot responds ✓
3. User clicks the history (clock) icon at the top of the assistant panel
4. User clicks "+" to start a new thread
5. Thread shows "Waiting for [Bot] to start a conversation…" and input is blocked permanently

No event ever fires. Verified with a catch-all raw event listener (app.event(/.*/, ...)) — zero events of any type are received when "+" is clicked.

Evidence

// First thread — works correctly:
[slack] threadStarted: fired {"type":"assistant_thread_started","assistant_thread":{"thread_ts":"1772128275.802869",...}}
[slack] threadStarted: say() done
[slack] threadContextChanged: fired {"type":"assistant_thread_context_changed","assistant_thread":{"thread_ts":"1772128275.802869",...}}
[slack] user=Anton duration=10636ms status=ok

// User clicks "+" for a second new thread — complete silence:
// [nothing received — no events of any type]

Impact

The thread is permanently stuck. Slack's UI blocks user input until the bot sends the first message, but since no event fires, the bot has no way to know a new thread was created. The user cannot recover without closing and reopening the assistant panel.

Reproducible in both Slack desktop app and Slack web browser.

Environment

• @slack/bolt: 4.6.0 (latest)
• Node.js: v22.22.0
• Socket Mode: yes

[zimeg]

Hey @anton-chernov-nrich! 👋 Thanks for sharing this detailed report 🙏 ✨

I can confirm new threads keep loading and will share with the team for search toward the cause. Let's keep this issue open in the meantime!

[github-actions]

👋 It looks like this issue has been open for 30 days with no activity. We'll mark this as stale for now, and wait 10 days for an update or for further comment before closing this issue out. If you think this issue needs to be prioritized, please comment to get the thread going again! Maintainers also review issues marked as stale on a regular basis and comment or adjust status if the issue needs to be reprioritized.

[github-actions]

As this issue has been inactive for more than one month, we will be closing it. Thank you to all the participants! If you would like to raise a related issue, please create a new issue which includes your specific details and references this issue number.