Cursor AI edits corrupt Windows-1252 encoding in C++ projects (even when editor shows 1252)

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1

Where does the bug appear (feature/product)?

Cursor IDE

Describe the Bug

Hello Cursor team,

I’m reporting a reproducible encoding corruption issue affecting C++ projects that use Windows-1252 (ANSI).

Environment

Cursor 2.4.27 (Stable)

VSCode 1.105.1

OS: Windows 10 x64

Project type: C++ (legacy codebase)

File encoding: Windows-1252

Line endings: CRLF

Project constraints

This is a legacy C++ project that must remain in Windows-1252 for compatibility reasons (toolchain, resource files, existing assets). Migrating to UTF-8 is not currently an option.

Configuration already applied

files.encoding = windows1252

files.autoGuessEncoding = false

EditorConfig with charset = windows-1252

.gitattributes with * text=auto

No format-on-save, no code actions on save

The problem

If I manually edit and save the file → no corruption

If I ask Cursor AI to do a minimal change (e.g. remove a single line) and apply it:

The entire file content gets corrupted

Accented characters (ç, ã, é, etc.) turn into ç, ã, é, etc.

Status bar still shows “Windows-1252”, even though the bytes were clearly rewritten incorrectly

This strongly suggests that the AI apply / patch mechanism rewrites the file as UTF-8 internally, ignoring the original encoding, while the UI continues to report Windows-1252.

Key observation

The corruption does not happen on open or manual save — it happens only when Cursor AI applies changes.

Expected behavior

When applying AI edits:

Preserve the original file encoding

Or at least detect non-UTF-8 encodings and avoid rewriting the full file

Impact

This makes Cursor unsafe to use on C++ legacy projects with non-UTF-8 encodings, as a single AI edit can silently corrupt the entire file.

Request

Is this a known issue?

Is there a setting or flag to force AI edits to respect the file’s original encoding?

If not, please consider this a bug report, as it breaks real-world C++ legacy codebases.

I’m happy to provide a minimal repro if needed.

Thanks.

Steps to Reproduce

Cursor 2.4.27 (Stable)

VSCode 1.105.1

OS: Windows 10 x64

Project type: C++ (legacy codebase)

File encoding: Windows-1252

Line endings: CRLF

Expected Behavior

…

Operating System

Windows 10/11

Version Information

Cursor 2.4.27 (Stable)

VSCode 1.105.1

OS: Windows 10 x64

Project type: C++ (legacy codebase)

File encoding: Windows-1252

Line endings: CRLF

Does this stop you from using Cursor

Yes - Cursor is unusable

3

Hey, thanks for the detailed report.

Related threads:

What definitely DOESN’T work (other users tried it):

  • Manual “Reopen/Save with Encoding”
    • The corruption already happened on the server before the diff came back to the editor
  • User rules in .cursorrules
    • Doesn’t help because the corruption happens in the apply pipeline, not in the prompt
  • files.encoding settings and .editorconfig
    • They get ignored

What works right now:
Downgrade to version 2.3.41 from Download · Cursor and turn off auto-update. A few users in the threads above confirmed the issue doesn’t reproduce on 2.3.x.

4

This version is also having problems. What’s going on? Why aren’t you fixing this? There are already a lot of complaints and nobody is resolving it; I’m going to cancel my plan

.