[BUG] Windows: Output renders as blank lines / excessive whitespace

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?

Claude Code output shows blank lines instead of actual text content on Windows.

When I run any command, the response renders with excessive whitespace/blank lines. Only partial text is visible at the top and bottom of the response. The middle content is completely blank.

Tested on:

• PowerShell 7 (standalone)
• PowerShell 5 (Windows Terminal)
• VS Code integrated terminal

All have the same issue. UTF-8 encoding is confirmed (chcp 65001).

What Should Happen?

Output text should display correctly without blank lines

Error Messages/Logs

Steps to Reproduce

1. Open PowerShell 7 or VS Code terminal on Windows
2. Run claude
3. Ask any question (e.g. "analyze this file")
4. Response shows blank lines instead of text

Claude Model

Sonnet (default)

Is this a regression?

I don't know

Last Working Version

_No response_

Claude Code Version

2.0.73

Platform

Anthropic API

Operating System

Windows

Terminal/Shell

PowerShell

Additional Information

<img width="1618" height="1673" alt="Image" src="https://github.com/user-attachments/assets/deadec18-d17a-49f8-bf1e-e1e34a348093" />

<img width="1596" height="683" alt="Image" src="https://github.com/user-attachments/assets/53fd8bbd-d470-4c06-91a9-8e421241792f" />