Powershell Utf8 Fixer

---
name: powershell-utf8-fixer
description: Detect and fix PowerShell script encoding issues that cause Korean and other non-ASCII characters to display incorrectly on Windows. Use when (1) PowerShell scripts display garbled Korean/non-ASCII text, (2) creating new .ps1 files with non-ASCII content, (3) validating encoding before committing PowerShell scripts, or (4) troubleshooting character display issues in PowerShell output.
model: claude-haiku-4-5-20251001
---

# PowerShell UTF-8 Fixer

## Problem

PowerShell on Windows requires UTF-8 with BOM encoding for scripts containing non-ASCII characters (Korean, Chinese, Japanese, emoji, etc.). Without the BOM (Byte Order Mark), PowerShell interprets the file using the system's default encoding (typically CP949 on Korean Windows), causing character display issues.

**Symptoms:**
- Korean text appears as `???` or garbled characters
- Emoji and special characters don't display correctly
- `Write-Host` output shows corrupted text
- One script works fine while another with identical code shows garbled text

**Root cause:** File encoding mismatch
- ✓ UTF-8 with BOM (EF BB BF): PowerShell reads correctly
- ✗ UTF-8 without BOM: PowerShell uses system default encoding → garbled text

## Quick Fix

When encountering encoding issues in PowerShell scripts:

1. **Check encoding:**

```bash
node scripts/check_powershell_encoding.js <file_or_directory>
# Or with npm:
npm run check <file_or_directory>
```

2. **Fix encoding:**

```bash
node scripts/fix_powershell_encoding.js <file_or_directory>
# Or with npm:
npm run fix <file_or_directory>
```

## Workflow

### When Creating New PowerShell Scripts

After creating any `.ps1` file with non-ASCII characters:

```bash
node scripts/fix_powershell_encoding.js script.ps1
```

This ensures the file is saved with UTF-8 BOM from the start.

### When Diagnosing Display Issues

If a PowerShell script shows garbled text:

1. Check the encoding:

```bash
node scripts/check_powershell_encoding.js problematic_script.ps1
```

2. If it shows "UTF-8 without BOM", fix it:

```bash
node scripts/fix_powershell_encoding.js problematic_script.ps1
```

3. Test the script again - text should now display correctly

### Batch Processing

To check/fix all PowerShell scripts in a directory:

```bash
# Check all scripts
node scripts/check_powershell_encoding.js scripts/windows/

# Fix all scripts that need it
node scripts/fix_powershell_encoding.js scripts/windows/
```

## Prevention

To prevent encoding issues in the future:

1. **Before committing:** Run the checker on modified `.ps1` files
2. **In CI/CD:** Add encoding validation to your pipeline
3. **Editor settings:** Configure your editor to save `.ps1` files as UTF-8 with BOM

### Editor Configuration Examples

**VS Code** (settings.json):
```json
{
  "[powershell]": {
    "files.encoding": "utf8bom"
  }
}
```

**Cursor** (settings.json):
```json
{
  "[powershell]": {
    "files.encoding": "utf8bom"
  }
}
```

## Scripts

### check_powershell_encoding.js

Diagnoses encoding issues without modifying files.

**Usage:**
```bash
node scripts/check_powershell_encoding.js <file_or_directory>
```

**Output:**
- ✓ UTF-8 with BOM: File is correctly encoded
- ⚠ UTF-8 without BOM: File needs fixing
- ⚠ UTF-16: File uses UTF-16 encoding
- ✗ Unknown: Unable to detect encoding

**Exit codes:**
- 0: All files have UTF-8 BOM
- 1: Some files need fixing or have errors

### fix_powershell_encoding.js

Adds UTF-8 BOM to PowerShell files that don't have it.

**Usage:**
```bash
node scripts/fix_powershell_encoding.js <file_or_directory>
```

**Behavior:**
- Reads file content as UTF-8
- Writes back with UTF-8 BOM (utf-8-sig)
- Skips files that already have UTF-8 BOM
- Processes `.ps1` files recursively in directories

**Exit codes:**
- 0: All files processed successfully
- 1: Errors occurred during processing

## Technical Details

**UTF-8 BOM:** The byte sequence `EF BB BF` at the start of a file signals UTF-8 encoding to PowerShell and other Windows applications.

**Why PowerShell needs BOM:**
- Without BOM, PowerShell uses `[Console]::OutputEncoding` (often CP949/CP1252)
- With BOM, PowerShell correctly identifies the file as UTF-8
- This is specific to Windows PowerShell's file reading behavior

**Alternative workarounds** (not recommended):
- Adding encoding commands to each script (verbose, error-prone)
- Using `-Encoding UTF8` parameters (doesn't help with file reading)
- Avoiding non-ASCII characters (limits usability)

The proper solution is to save files with UTF-8 BOM.