[BUG] barber pole looking color corruption

Preflight Checklist

• [x] I have searched existing issues and this hasn't been reported yet
• [x] This is a single bug report (please file separate reports for different bugs)
• [x] I am using the latest version of Claude Code

What's Wrong?

on my windows machine, output renders in arbitrary colors in weird patterns, in what appears intermittent. This is first time setting up claude w/ windows , so i am not sure if this has been this way before, or something wrong with my shell, or something wrong with claude. I pasted a screen shot of the terminal output and part of /export of chat.

exploring the issue w/ claude - seems to think the issue is claude code

What Should Happen?

claude only outputs markdown therefore something in rendering the markdown to the shell may be adding color in unexpected ways

Error Messages/Logs

Steps to Reproduce

open claude code on windows powershell, arbitrary colorization may occur

Claude Model

Opus

Is this a regression?

I don't know

Last Working Version

_No response_

Claude Code Version

2.1.17

Platform

Anthropic API

Operating System

Windows

Terminal/Shell

PowerShell

Additional Information

🤖
Component: Claude Code
Version: 2.1.17
────────────────────────────────────────
Component: PowerShell
Version: 7.5.4
────────────────────────────────────────
Component: Windows
Version: 10.0.26200.0
────────────────────────────────────────
Component: Terminal
Version: Windows Terminal 1.23.13503.0
────────────────────────────────────────
Component: Color Scheme
Version: Kanagawa (custom) / One Half Dark (built-in)
Key observations to include:

• Colors appear to be applied based on screen position, not text

content

• Creates diagonal "barber pole" / flag-like patterns
• Persists across different terminal color schemes
• Affects prose text and code blocks equally
• Pattern suggests systematic offset (color state applied N

characters behind, N increasing per line)

<img width="1887" height="1121" alt="Image" src="https://github.com/user-attachments/assets/7c6da016-9af6-44f5-bccc-cc09708c7084" />

barberpole-bug.txt