[BUG] VS Code extension: unattended in-chat question causes native binary to spin at ~99% CPU indefinitely

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?

Related: #19393, #30807 — but this report specifically isolates the trigger (an unanswered in-chat question in the VS Code extension) rather than general idle state.

Description:
When Claude Code (VS Code extension) asks a question in the chat panel and the user does not respond, the underlying native binary process keeps running and consumes ~99-100% CPU continuously, seemingly indefinitely, until manually killed.

Environment:

• Extension: anthropic.claude-code v2.1.179 (darwin-x64)
• OS: macOS (MacBook Pro)
• Process: .../native-binary/claude --output-format stream-json

Observed behavior:
The claude process (native binary spawned by the extension) shows sustained ~99.5% CPU usage. In my case it accumulated 2:47:36 of CPU time while idle-waiting for a response, and the fan ran continuously / MacBook got noticeably hot.

What Should Happen?

Expected behavior:
While waiting for user input on an open question, the process should idle at ~0% CPU rather than actively spinning.

Error Messages/Logs

Steps to Reproduce

1. Start a Claude Code session in the VS Code chat panel
2. Claude asks a question mid-task (e.g. "Do you want me to build this section in the Studio modal?")
3. Leave the question unanswered (switch away, don't respond)
4. Check Activity Monitor after some time

Claude Model

Not sure / Multiple models

Is this a regression?

Yes, this worked in a previous version

Last Working Version

_No response_

Claude Code Version

anthropic.claude-code v2.1.179 (darwin-x64)

Platform

Anthropic API

Operating System

macOS

Terminal/Shell

VS Code integrated terminal

Additional Information

Confirmed via:

ps -p <39893> -o command

returned:

/Users/.../.vscode/extensions/anthropic.claude-code-2.1.179-darwin-x64/resources/native-binary/claude --output-format stream-json

lsof -p <> showed no unusual open files being actively written; process was purely CPU-bound while waiting.

Answering the question "Do you want me to build this section in the Studio modal?"
by prompting <No>
resolved the issue immediately.