[BUG] IDE auto-save buffer conflict still occurs in v2.1.74 (Cursor IDE, Windows)

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?

The IDE auto-save buffer conflict issue reported in #10882 and #32405 still reproduces in Claude Code v2.1.74 when using Cursor IDE on Windows.

Cursor IDE's auto-save overwrites Claude Code's Write/Edit results with the previous buffer content. This occurs when the IDE has the same file open that Claude Code is editing, particularly in multi-session scenarios.

Key difference from #10882: The original issue was reported with VSCode and was marked as fixed in a subsequent release. However, the same root cause persists in Cursor IDE (a VSCode fork), suggesting the fix may not fully cover all IDE variants or file-watching mechanisms.

What Should Happen?

Claude Code's Edit/Write operations should successfully persist to disk without being reverted by the IDE's auto-save or file watcher.

Steps to Reproduce

1. Open a project in Cursor IDE (Windows) with Claude Code CLI active
2. Have a file open in the Cursor editor (e.g., src/components/example.tsx)
3. Ask Claude Code to edit that file using the Edit tool
4. Claude reads the file, applies the edit → Edit succeeds momentarily
5. Cursor IDE's auto-save triggers within ~100-500ms, reverting the file to its previous buffer state
6. The edit is silently lost — git diff shows no changes

Workaround currently in use:

• Set files.autoSave: "off" in both project and user-level VSCode/Cursor settings
• This mitigates but doesn't fully prevent the issue in multi-session scenarios

Reproduction Rate

~30-50% of Edit operations when Cursor has the target file open. Higher rate when:

• Multiple Claude Code sessions are active
• The file was recently edited in the IDE
• The file has formatters (Prettier/ESLint) configured

Error Messages/Logs

No explicit error message — the edit appears to succeed but is silently reverted by the IDE. The only indication is:

$ git diff --stat
# (empty — no changes)

When the Edit tool output showed successful modification.

Claude Model

claude-sonnet-4-20250514

Is this a regression?

Yes — #10882 was closed as fixed, but the issue persists in Cursor IDE

Last Working Version

_Not applicable — issue has persisted across versions_

Claude Code Version

Claude Code v2.1.74

Platform

Anthropic API

Operating System

Windows 11

Terminal/Shell

PowerShell / Git Bash

Additional Information

• Related issues: #10882 (closed as fixed), #32405 (closed as duplicate of #10882), #7918 (path tracking)
• IDE: Cursor (VSCode fork) — may have different file-watching behavior than vanilla VSCode
• Mitigation: files.autoSave: "off" + avoiding opening files being edited by Claude in the IDE
• Impact: Silent data loss — edits appear to succeed but are reverted, causing significant reliability issues in development workflows