Residual 'M' character from 'Mulling...' spinner bleeds into response output

Description

When Claude Code displays the "Mulling..." thinking spinner and then transitions to streaming the response, the first character "M" from "Mulling..." is not properly cleared from the terminal. This results in the response text being prefixed with a stray "M" character.

For example, a response that should display as:

どういたしまして！

Instead displays as:

Mどういたしまして！

Steps to Reproduce

1. Send a message to Claude Code that triggers a short response
2. Observe "Mulling..." spinner appears during thinking
3. When the response starts streaming, the "M" from "Mulling..." remains on screen before the actual response text

Expected Behavior

The "Mulling..." spinner text should be fully cleared from the terminal before the response text begins streaming.

Actual Behavior

The "M" character from "Mulling..." persists and is prepended to the beginning of the response output.

Environment

• OS: Windows 11 Pro 10.0.26200
• Terminal: Windows Terminal (integrated in CLI)
• Claude Code: latest channel

Screenshot

!screenshot

The screenshot shows:

• "Mulling..." spinner appearing
• Response "どういたしまして！" displayed with a leading "M" → "Mどういたしまして！"

Additional Notes

• This occurs intermittently but frequently enough to be noticeable
• Affects readability of responses, especially short ones
• Appears to be a terminal rendering/cursor positioning issue when transitioning from spinner to output