[BUG] File Unexpectedly Modified when file timestamp changes

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?

Whenever file timestamp (updated at) changes, Claude Code errors out and needs to read the file again.
I believe this is a bug.

When Claude Code needs to read the file _contents_, it shouldn't fail due to file _metadata_ changing.

Please fix as this is making Claude Code slower.

What Should Happen?

If file _contents_ didn't change, as far as Claude Code is concerned, the file didn't change.

Error Messages/Logs

Steps to Reproduce

1. Tell Claude Code to update a certain file
2. After Claude Code reads the file, but before it makes any edits, save the file

You can repeat this process as many times as you want.
Think if there was an automated file watcher that automatically runs some formatter that, unfortunately, modifies file timestamp even if the contents didn't change.

Claude Model

None

Is this a regression?

No, this never worked

Last Working Version

_No response_

Claude Code Version

v2.0.44

Platform

Anthropic API

Operating System

macOS

Terminal/Shell

Cursor

Additional Information

_No response_