Chinese characters in code are garbled in recent Codex versions

What version of Codex is running?

codex-cli 0.42.0

Which model were you using?

gpt-5-codex high

What platform is your computer?

Windows 11 Home 64-bit

What steps can reproduce the bug?

When generating code that contains Chinese characters (for example, comments or strings), Codex outputs garbled text instead of proper Chinese.

Steps to reproduce:

1. Ask Codex to generate a simple program with Chinese comments or string literals.

Example prompt: "Write a Python program that prints '你好世界' and add a Chinese comment."

1. The output code will show corrupted characters instead of correct Chinese.

Expected behavior:
Codex should output proper UTF-8 encoded Chinese characters in the generated code.

Actual behavior:
Codex outputs garbled/unreadable characters (mojibake) instead of Chinese.

What is the expected behavior?

Codex should correctly generate and display Chinese characters (UTF-8 encoding) inside code, including comments and string literals. For example, when generating:

print("首頁")

It should show exactly as above.

What do you see instead?

Instead of showing correct Chinese characters, Codex outputs corrupted/garbled text (mojibake). For example, the above code becomes something like:

print("����'")

Additional information

• This issue started happening in recent versions of Codex. Older versions could display Chinese correctly.
• The problem occurs consistently on Windows 11 (64-bit) environment.
• The bug makes it difficult for developers who use Chinese (or other non-Latin scripts) to generate code with comments or string literals in their own language.
• It seems to be an encoding regression, possibly related to UTF-8 handling.