Excessive whitespace in response output on Windows (CMD/PowerShell)

Claude Code Bug Report: Excessive Whitespace in Response Output on Windows

Issue Summary

Claude Code responses contain excessive vertical whitespace when running on Windows (both CMD and PowerShell), making the output nearly unreadable. Text fragments are scattered across the screen with massive gaps between lines.

Environment

• OS: Windows 11 (Build 26100.0)
• Terminals Affected:
• Windows Command Prompt (CMD)
• PowerShell
• Claude Code Version: 2.0.73
• Date Observed: December 19, 2025

Steps to Reproduce

1. Launch Claude Code in Windows CMD or PowerShell
2. Ask any question that generates a multi-paragraph response
3. Observe the output rendering

Expected Behavior

Response text should be rendered as continuous, readable paragraphs with normal line spacing, similar to:

Service Status Summary

Here's the current status of all Brokermatic platform services:

✅ Running Services

Frontend Applications:
- Marketing Website (port 3000) - Running
- Agency Manager (port 3002) - Running

Actual Behavior

Response text is rendered with excessive vertical whitespace (10+ blank lines between text fragments), resulting in:

• Text scattered across screen with massive gaps
• Difficult to follow coherent thoughts
• Poor user experience
• Wasted terminal space

Visual Evidence

See attached screenshot: Screenshot 2025-12-19 094821.png

The screenshot shows:

• Tool results at top of screen
• Mid-response text fragment "s, Roles, Sessions, Certificates..." appearing ~50% down screen
• Another fragment "ot running. This service handles:" appearing ~70% down screen
• Final question at bottom of screen
• Massive blank spaces between all text elements

Impact

• Severity: High - Makes Claude Code nearly unusable on Windows
• Frequency: Every response with multiple paragraphs
• User Impact: Forces users to scroll excessively, makes it hard to understand responses

Technical Observations

1. Issue appears to affect markdown/formatted text rendering
2. Tool results (Bash, Read, etc.) seem to render normally
3. Natural language response text is where excessive spacing occurs
4. Text content is not lost, just improperly spaced
5. Affects both CMD and PowerShell (not terminal-specific)

Possible Causes to Investigate

1. Windows line ending handling (CRLF vs LF)
2. Terminal control character interpretation on Windows
3. Markdown rendering engine differences between platforms
4. Buffer flushing behavior on Windows terminals

Workarounds

• WSL2: Using Windows Subsystem for Linux may provide better rendering (not tested)
• Third-party terminals: Windows Terminal app might handle rendering differently (not tested)

Request

Please investigate the Windows-specific rendering pipeline for Claude Code responses and fix the excessive whitespace issue. This significantly degrades the user experience on Windows platforms.

Additional Context

• This issue was discovered during regular development work
• User was checking service status and received fragmented output
• Issue persists across multiple Claude Code sessions
• No known terminal configuration that fixes this

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To submit this bug report:

1. Go to: https://github.com/anthropics/claude-code/issues
2. Click "New Issue"
3. Copy this report content
4. Attach screenshot: Screenshot 2025-12-19 094821.png
5. Submit