[BUG] support for non-UTF-8 file encodings (e.g., GB2312) to prevent file corruption

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?

When using Claude Code to edit local files encoded in GB2312 (common in Chinese environments), the tool writes content back in UTF-8 without converting the existing encoding. This results in Chinese characters becoming garbled (mojibake) and corrupts the source files.

What Should Happen?

Claude Code should:

Automatically detect the file's encoding before reading/writing.

Or, provide a configuration option (e.g., in a .claudecodeconfig or via flag) to specify the project's default encoding.

Or, at least warn the user if the file is not UTF-8 encoded.

Error Messages/Logs

Steps to Reproduce

Open a project where source files are encoded in GB2312.

Ask Claude Code to modify a file containing Chinese characters.

Claude Code applies the edit.

Open the file in an editor; all Chinese characters are corrupted.

Claude Model

None

Is this a regression?

Yes, this worked in a previous version

Last Working Version

_No response_

Claude Code Version

v2.1.79

Platform

Anthropic API

Operating System

Windows

Terminal/Shell

PowerShell

Additional Information

_No response_