[BUG] Shell parser crash on Math.round - Bad substitution error

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?

Claude Code crashes with a shell parsing error when encountering Math.round in JavaScript code. The crash occurs in the shell command
parsing logic with the error: Error: Bad substitution: Math.round.

## Stack Trace
Error: Bad substitution: Math.round
at D (file:///home/robertspeer/.claude/local/node_modules/@anthropic-ai/claude-code/cli.js:80:79195)
at file:///home/robertspeer/.claude/local/node_modules/@anthropic-ai/claude-code/cli.js:80:79854
at Array.map ()
at eZ9 (file:///home/robertspeer/.claude/local/node_modules/@anthropic-ai/claude-code/cli.js:80:78933)
at Object.A (file:///home/robertspeer/.claude/local/node_modules/@anthropic-ai/claude-code/cli.js:80:80018)
at _j6 (file:///home/robertspeer/.claude/local/node_modules/@anthropic-ai/claude-code/cli.js:1757:29074)
at fj6 (file:///home/robertspeer/.claude/local/node_modules/@anthropic-ai/claude-code/cli.js:1757:32565)
at file:///home/robertspeer/.claude/local/node_modules/@anthropic-ai/claude-code/cli.js:1757:33114
at Array.every ()
at Q0B (file:///home/robertspeer/.claude/local/node_modules/@anthropic-ai/claude-code/cli.js:1757:33052)

## Environment

• Platform: Linux 6.12.10-76061203-generic
• Working Directory: /home/robertspeer/Projects/GitRepo/nearest-nice-weather
• Project Type: Node.js/JavaScript project

## Root Cause Analysis
The shell command parser incorrectly interprets Math.round as a variable substitution pattern (like ${variable}) instead of treating it
as literal JavaScript code. The parser fails when trying to process this as a shell variable substitution.

## Reproduction
This appears to occur when:

1. Working with JavaScript code containing Math.round
2. Claude Code attempts to parse or validate shell commands
3. The Math.round text gets passed through the shell parser incorrectly

## Expected Behavior
Math.round in JavaScript code should not be interpreted as shell variable substitution syntax.

## Actual Behavior
Claude Code crashes with "Bad substitution" error and becomes unresponsive.

## Suggested Fix
The shell parser should properly escape or handle JavaScript expressions to avoid misinterpreting them as shell syntax.

---

Personal Note: @Boris @Cat - Thank you both for your excellent work on Claude Code! Really appreciate all the effort you put into making
this tool amazing. 🙏

I was unable to recreate the issue.

What Should Happen?

not crashing and kicking me out of Claude Code

Error Messages/Logs

Error: Bad substitution: Math.round
      at D (file:///home/robertspeer/.claude/local/node_modules/@anthropic-ai/claude-code/cli.js:80:79195)
      at file:///home/robertspeer/.claude/local/node_modules/@anthropic-ai/claude-code/cli.js:80:79854
      at Array.map (<anonymous>)
      at eZ9 (file:///home/robertspeer/.claude/local/node_modules/@anthropic-ai/claude-code/cli.js:80:78933)
      at Object.A (file:///home/robertspeer/.claude/local/node_modules/@anthropic-ai/claude-code/cli.js:80:80018)
      at _j6 (file:///home/robertspeer/.claude/local/node_modules/@anthropic-ai/claude-code/cli.js:1757:29074)
      at fj6 (file:///home/robertspeer/.claude/local/node_modules/@anthropic-ai/claude-code/cli.js:1757:32565)
      at file:///home/robertspeer/.claude/local/node_modules/@anthropic-ai/claude-code/cli.js:1757:33114
      at Array.every (<anonymous>)
      at Q0B (file:///home/robertspeer/.claude/local/node_modules/@anthropic-ai/claude-code/cli.js:1757:33052)

Steps to Reproduce

I was unable to reproduce

Claude Model

Sonnet (default)

Is this a regression?

I don't know

Last Working Version

_No response_

Claude Code Version

v1.0.110

Platform

Anthropic API

Operating System

Other Linux

Terminal/Shell

Other

Additional Information

happened working on this repository:
https://github.com/PrairieAster-Ai/nearest-nice-weather