[BUG] Sub-agent status line repeatedly prints new lines instead of updating in place

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?

When running sub-agents (e.g., Explore agent via Task tool), the status indicator that should remain fixed at the bottom of the terminal is instead being printed repeatedly as new lines, causing the screen to
scroll continuously with duplicate status messages.

What Should Happen?

Actual Behavior
The status line is printed repeatedly, creating many duplicate lines with large gaps between them. The terminal scrolls continuously while the agent runs, making it impossible to see other content.

Expected Behavior
The agent status (e.g., ● Explore(Find entity attribute patterns)) should display as a single, updating status line at the bottom of the terminal, similar to how other long-running operations display.

Error Messages/Logs

Steps to Reproduce

1. Start Claude Code
2. Ask a question that triggers a sub-agent (e.g., "What is the codebase structure?" which triggers Explore agent)
3. Observe the terminal output while the agent runs

Claude Model

Opus

Is this a regression?

Yes, this worked in a previous version

Last Working Version

2.0.76

Claude Code Version

2.1.4

Platform

Anthropic API

Operating System

Windows

Terminal/Shell

Windows Terminal

Additional Information

<img width="797" height="511" alt="Image" src="https://github.com/user-attachments/assets/e1b7d3fe-cd61-4b8f-8b9b-5a9fe7202e1a" />