[BUG]

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?

Problem
The Edit and Write tools do not preserve file ownership and permissions. When editing a file owned by e.g. root:apache with mode 640, the file becomes root:root with mode 644 after the edit.

This indicates the tools replace the file (write new file + rename) rather than modifying it in-place, which resets ownership to the process owner.

Impact
On systems where file ownership matters — particularly web servers running PHP — this causes immediate breakage:

• Blank pages / HTTP 500 errors when the web server (running as apache) can no longer read PHP files that were changed to root:root 640
• Every single edit requires a manual chown/chmod fix afterward
• Easy to forget, leading to hard-to-diagnose production issues
• Must be documented in CLAUDE.md as a workaround, adding cognitive overhead to every session

What Should Happen?

The Edit and Write tools should preserve the original file's ownership (uid:gid) and permissions (mode) after modification — the same way sed -i, patch, or any in-place editor does.

Suggested fix
After writing the file, restore the original ownership and permissions:

  import os, stat

  # Before writing: capture original metadata
  st = os.stat(filepath)
  original_uid = st.st_uid
  original_gid = st.st_gid
  original_mode = stat.S_IMODE(st.st_mode)

perform the write/replace ...

After writing: restore metadata

  os.chown(filepath, original_uid, original_gid)
  os.chmod(filepath, original_mode)

Alternatively, write to the file in-place (open + truncate + write) instead of using a temp file + rename pattern.

Environment

• Claude Code CLI running as root on RHEL 9
• Editing PHP files owned by root:apache with mode 640
• Both Edit and Write tools exhibit this behavior

Error Messages/Logs

Steps to Reproduce

Create a file with specific ownership

echo "test" > /tmp/testfile.txt
chown root:apache /tmp/testfile.txt
chmod 640 /tmp/testfile.txt
ls -la /tmp/testfile.txt
# -rw-r----- root apache

Use the Claude Code Edit tool to modify the file

 ls -la /tmp/testfile.txt
 -rw-r--r-- root root   _**<-- ownership and permissions changed**_

Claude Model

Opus

Is this a regression?

No, this never worked

Last Working Version

_No response_

Claude Code Version

2.1.79 (Claude Code)

Platform

Anthropic API

Operating System

Other Linux

Terminal/Shell

Xterm

Additional Information

_No response_