[Bug] Edit tool reports file modified when hash unchanged on Windows with autocrlf

Bug Description
Bug Report Summary

Issue: Edit tool reports "File has been unexpectedly modified" when the file hasn't actually changed

Evidence:

• md5sum shows file hash remains constant across multiple reads
• No external processes modifying files (verified by killing Jest watcher)
• VS Code was closed during testing
• package.json edits work fine, but .ts and .md files consistently fail
• Issue persists even with empty file watcher list

Environment:

• Windows 10 (version 10.0.26200.7171)
• Git Bash shell
• core.autocrlf=true in git config
• Claude Code CLI via npm

Steps to reproduce:

1. Read a .ts or .md file
2. Immediately attempt an Edit
3. Error occurs even though file hasn't changed

Workaround: Use Write to create new file + mv to replace, or use sed for inline edits

Environment Info

• Platform: win32
• Terminal: null
• Version: 2.0.55
• Feedback ID: 6507f856-8081-4bb6-b62e-a593f1c7d6bb

Errors