[BUG] Text truncation and Markdown rendering corruption on Windows Terminal

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?

Description

Claude Code responses are being truncated and corrupted when displayed in Windows Terminal. Only plain text inside code blocks renders correctly. Regular Markdown-formatted text (paragraphs, bold, lists, tables, headers) gets truncated, shifted to the right with large whitespace gaps, or completely missing.

## Environment

• OS: Windows (Windows Terminal + PowerShell)
• Claude Code version: 2.0.73
• Terminal: Windows Terminal (also tested in CMD.exe - same issue)
• Fonts tested: Cascadia Code (default), Consolas

## Symptoms

1. Text truncation: Lines of text are cut off mid-sentence
2. Right-shifting: Text appears far to the right with blank space on the left
3. Missing content: Entire paragraphs or sections disappear
4. Last line of code blocks: Often gets cut off
5. Markdown tables: Completely broken
6. Bold text, numbered lists, headers: Cause surrounding text to break

## What Works

• Plain text inside code blocks displays correctly
• Emojis and Unicode characters display fine
• The very last line of output is usually visible

## Reproduction Steps

1. Start Claude Code in Windows Terminal with PowerShell
2. Ask any question that generates a multi-paragraph Markdown response
3. Observe truncated/shifted output

## Troubleshooting Already Attempted

• Changed font to Consolas - no improvement
• Tested in CMD.exe - same issue
• Reinstalled Claude Code - same issue
• Changed output_style setting - same issue
• Widened terminal window - no improvement

## Workaround

Asking Claude to respond only in plain text code blocks works.

What Should Happen?

Full Markdown-formatted responses should display correctly.

Error Messages/Logs

Steps to Reproduce

1. Launch Claude Code in windows terminal
2. Provide a prompt and wait for response
3. Notice that some of the characters are missing.

Claude Model

Sonnet (default)

Is this a regression?

Yes, this worked in a previous version

Last Working Version

_No response_

Claude Code Version

2.0.73

Platform

Anthropic API

Operating System

Windows

Terminal/Shell

Windows Terminal

Additional Information

This started happening when Claude removed some WSL messages from my files. I used to run on the WSL install but moved to the windows install.