[BUG] Sandbox incorrectly escapes the '!' character when present in a Bash tool call

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?

Certain bash tool calls might have a ! present in them, e.g. with Maven you can ignore certain modules with !.

However, the sandbox will escape the ! regardless of where it is in the call, even if it is within a string

mvn clean install -DskipTests -T1C -pl '!python'

What Should Happen?

The ! character should not be escaped when it is inside of a string

Error Messages/Logs

Steps to Reproduce

Run Claude Code within a sandbox (/sandbox), and then ask Claude to execute a bash command with a ! within a string.

echo "hello!"

this outputs, incorrectly

hello\!

Claude Model

Opus

Is this a regression?

I don't know

Last Working Version

_No response_

Claude Code Version

2.1.85

Platform

Anthropic API

Operating System

Other Linux

Terminal/Shell

Xterm

Additional Information

_No response_