[BUG] Claude cannot see any `npm run` outputs anymore

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?

After update to last version claude stopped being able to see output of commands in bash. It sees partial output, but not complete.

What Should Happen?

Claude should see npm output and work on it.

Error Messages/Logs

Steps to Reproduce

1. setup minimal nodejs project
2. ask claude to do something like: run npm run test in frontend folder and summarize results

It would see some stuff, but mostly empty output. Looks like an issue with capturing stderr.

Claude Model

None

Is this a regression?

Yes, this worked in a previous version

Last Working Version

2.1.7

Claude Code Version

2.1.12

Platform

Anthropic API

Operating System

Windows

Terminal/Shell

VS Code integrated terminal

Additional Information

I tried instructing it to do experiments with "echo", but it sees all output from bash:

● Bash(echo "this is stdout" && echo "this is stderr" 1>&2)
  ⎿  this is stdout
     this is stderr

● Both stdout and stderr are captured correctly.