charset-fix

Windows Character Encoding Fix for AI Agents

Fix garbled Chinese/Unicode text output when running AI agents on Windows through POSIX-compatible shells.

Problem

When AI agents run commands on Windows through POSIX shells (Git Bash, MSYS2, BusyBox, or any Unix-like shell layer), text output containing Chinese or extended Unicode characters often appears garbled:

$ python3 -c "print('中文测试')"
���Ĳ���  ← garbled
$ echo "中文测试"
中文测试       ← correct

Root Cause

Layer	Encoding	Why
Windows system	GBK/GB2312 (CP936)	Default code page for Chinese Windows
Python 3	GBK	`sys.stdout.encoding` auto-detects system code page
PowerShell (powershell.exe)	GB2312	`[Console]::OutputEncoding` defaults to system CP
cmd.exe	GBK	Native Windows command processor
POSIX shell (Git Bash, BusyBox, MSYS2)	UTF-8	Expects UTF-8 input
PowerShell Core (pwsh.exe)	UTF-8	✅ Defaults to UTF-8, no fix needed

The mismatch: Windows-native tools output GBK-encoded text, but the POSIX shell terminal reads it as UTF-8, producing garbled characters.

Quick Fix

Python

PYTHONIOENCODING=utf-8 python3 -c "print('中文测试 ✅')"

Set it for the whole session:

export PYTHONIOENCODING=utf-8
python3 script.py

PowerShell (Windows PowerShell, not Core)

powershell.exe -NoProfile -Command "[Console]::OutputEncoding = [System.Text.Encoding]::UTF8; Write-Host '中文测试'"

cmd.exe / Windows native tools

Use Python's subprocess as a GBK→UTF-8 bridge:

PYTHONIOENCODING=utf-8 python3 -c "
import subprocess
r = subprocess.run(['cmd.exe', '/c', 'systeminfo | findstr 系统'],
    capture_output=True, text=True, encoding='gbk')
print(r.stdout)
"

Code-level fix (Python)

import sys, io
sys.stdout = io.TextIOWrapper(sys.stdout.buffer, encoding='utf-8')

Verification

PYTHONIOENCODING=utf-8 python3 -c "print('charset-fix: 中文测试成功 ✅')"

Expected: charset-fix: 中文测试成功 ✅

How It Works

Fix	Mechanism
`PYTHONIOENCODING=utf-8`	Overrides Python's stdout encoding detection
`[Console]::OutputEncoding = UTF8`	Sets PowerShell's console output to UTF-8
`subprocess(..., encoding='gbk')`	Decodes cmd.exe output correctly, then emits as UTF-8

Compatibility

Platform	Status
Windows + Git Bash	✅ Works
Windows + BusyBox	✅ Works
Windows + MSYS2	✅ Works
Windows + WSL	✅ Works
macOS / Linux	⬜ Not needed
PowerShell Core (pwsh)	⬜ Not needed

Works with: Claude Code, Codex CLI, Cline, Cursor, GitHub Copilot, OpenClaw agents.

Debugging

# Check code page
powershell.exe -NoProfile -Command "chcp"

# Check Python encoding
python3 -c "import sys; print(sys.stdout.encoding)"

# Test raw shell output
echo "中文测试"

License

MIT