[BUG] Sandbox: Bash cwd tracking writes to blocked /tmp/ path causing error noise on all commands

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 sandbox mode is enabled, every bash command fails with exit code 1 and error message /tmp/claude-{random}-cwd: Read-only file system, even though the actual command succeeds. This pollutes logs and makes successful test runs appear failed.

The bash integration writes cwd tracking files to /tmp/claude-{random}-cwd which is outside the sandbox-allowed /tmp/claude/ directory, causing write failures.

What Should Happen?

Bash cwd tracking files should be written to /tmp/claude/cwd-{random} (inside sandbox-allowed directory) and commands should return clean exit codes when operations succeed.

Error Messages/Logs

Error: Exit code 1
/bin/bash: line 4: /tmp/claude-a1b2-cwd: Read-only file system

[actual command output here - successful]

Steps to Reproduce

1. Enable sandbox mode in settings
2. Run any bash command (e.g., ls, git status, pytest)
3. Observe error in output despite command succeeding

Claude Model

Sonnet (default)

Is this a regression?

I don't know

Last Working Version

_No response_

Claude Code Version

2,0,37

Platform

Anthropic API

Operating System

Other Linux

Terminal/Shell

Other

Additional Information

OS: manjaro.
Terminal: konsole (zsh)

Proposed Solution:

Update bash tool integration to write cwd tracking files to ${TMPDIR}/cwd-{random} or hardcode /tmp/claude/cwd-{random} when sandbox is enabled.

One-line fix in bash tool code:
// Current: /tmp/claude-{id}-cwd
// Fixed: /tmp/claude/cwd-{id} or ${TMPDIR}/cwd-{id}

● Bash(echo a hello world)
  ⎿  Error: Exit code 1
     /bin/bash: line 4: /tmp/claude-f365-cwd: Read-only file system

     a hello world