Claude and Powershell 5 - Fixing PS1 files with Japanese and no BOM mark

Fixing PS1 files utf8 encoded files with no BOM mark and Japanese culture.md

I found these CLAUDE.md examples that help mitigate when claude or external tools are executed ie: Cases where you can't just modify your profile

The problem is powerh

Traditional fix for current user

In the file $Profile.CurrentUserAllHosts add

# This same line works on Powershell 5.1 and Pwsh 7+
$OutputEncoding = 
     [Console]::OutputEncoding = [Console]::InputEncoding =
     [System.Text.UTF8Encoding]::new( <# bool: encoderShouldEmitUTF8Identifier #> )

Or even set your global default like chcp 65001. But that can affect legacy apps if they force the culture as the implicit encoding type.

CLAUDE.md fixes

# Windows PowerShell Parameter Constraints
CRITICAL GLOBAL RULE: The host machine uses a Japanese system locale (CP932/Shift-JIS). 

Whenever you invoke external commands via the Windows PowerShell execution tool boundary that pass Japanese string arguments, you MUST prepend an explicit UTF-8 memory boundary wrapper. 

Never call parameters raw. Instead, format every shell invoke command like this:
powershell -NoProfile -Command "[Console]::InputEncoding = [System.Text.Encoding]::UTF8; [Console]::OutputEncoding = [System.Text.Encoding]::UTF8; <Your-Command-Here>"

~/.claude/settings.json fixes

{
  "hooks": {
    "PreToolUse": "[Console]::InputEncoding = [System.Text.Encoding]::UTF8; [Console]::OutputEncoding = [System.Text.Encoding]::UTF8;"
  }
}

Other things to try

When I've had issues with commands related to encoding, some of these have helped. They might be overlap with your case

• if wsl is involved -- that ignores encodings when piping. It forces utf-16le breaking the output streams. ( one fix: https://www.reddit.com/r/PowerShell/comments/1ijvi0g/comment/mbhixhr ) -- Or use a wrapper that switches switches to encoding utf-16le before piping from wsl then switch back to your original enocding
• Setting $ENV:LANG = 'C.UTF-8'
• (from above) Setting $OutputEncoding, and all [Console]::Input/Output encodings
  • I use [System.Text.UTF8Encoding]::new( $false ) intentionally because some cli apps break if you use the BOM version named [System.Text.UTF8Encoding]

$ENV:LANG = 'C.UTF-8'