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