[BUG] Text responses are intermittently truncated in Claude Code during streaming output on Windows

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

When using Claude Code on Windows, the assistant’s responses are intermittently truncated during streaming output.
Only part of the response is rendered in the terminal, and the remaining text is missing.

This occurs even though the response generation appears to complete normally, and no explicit error is shown.

Expected Behavior

The full response text should be displayed completely and consistently.

Actual Behavior

• The response text is cut off mid-sentence or mid-paragraph.
• The missing portion never appears, even after waiting.
• This happens intermittently but frequently enough to disrupt usage.

Environment

• OS: Windows 10 / Windows 11
• Shell: (e.g. Windows Terminal / PowerShell / CMD — adjust as needed)
• Claude Code version: (please fill in)
• Encoding: UTF-8
• Language: Occurs more frequently with Korean text, but not limited to it

Reproduction Steps

1. Run Claude Code in a Windows terminal
2. Ask a question that produces a multi-line or long response
3. Observe that the output is sometimes truncated during streaming

Additional Notes

• This appears related to streaming output handling on Windows terminals.
• Similar issues have been reported regarding truncation, corruption, and line spacing on Windows.
• Restarting the session does not reliably resolve the issue.

What Should Happen?

Claude’s responses should be displayed fully and correctly in the terminal without any truncation or missing lines.

Error Messages/Logs

Steps to Reproduce

1. Run Claude Code on Windows
2. Start an interactive session
3. Ask Claude a question that produces a long or multi-line response
4. Observe the output while the response is streaming

Claude Model

None

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

PowerShell

Additional Information

<img width="1410" height="696" alt="Image" src="https://github.com/user-attachments/assets/16efd149-2f81-4442-8cec-729530d7fd38" />