[BUG] Subagents going idle

Preflight Checklist

• [x] I have searched existing issues and this hasn't been reported yet
• [x] This is a single bug report (please file separate reports for different bugs)
• [x] I am using the latest version of Claude Code

What's Wrong?

When subagents are spawned, they seem to just take a break... I remember hitting this when Agent Teams came out and so I disabled that so only subagents would be used.

But it seems to plague subagents now.

I don't have any logs to show this but it is the same behavior. I'll kick off a workflow and come back 3 hours later. The same subagent is running, timer going up, no token usage.

I use the down arrow keys to switch to the subagent, type some random characters (don't actually submit a prompt), and bam the subagent starts working again.

Subagents are going idle, this has been happening to me since yesterday (June 25). It doesn't happen 100% of the time.

What Should Happen?

Subagents should not go idle.

Error Messages/Logs

Steps to Reproduce

Spawn a subagent for a long-ish running task

Claude Model

Sonnet (default)

Is this a regression?

Yes, this worked in a previous version

Last Working Version

_No response_

Claude Code Version

2.1.19

Platform

Anthropic API

Operating System

macOS

Terminal/Shell

Terminal.app (macOS)

Additional Information

_No response_