[BUG] Terminal re-renders entire conversation output repeatedly during sequential tool calls

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?

What's Wrong:
When Claude Code executes multiple sequential tool calls in one response (e.g. 4–5 file edits in a row), the terminal re-renders the entire previous conversation output from scratch
on each new chunk/result instead of appending. This causes every previous response block to appear repeated many times in the terminal scroll history.

Observed twice in the same session:

1. First response of the session (a markdown table) rendered ~20 times before the next prompt appeared.
2. During a sequence of 5 Edit tool calls to the same file, the full diff output block was re-rendered after each call — resulting in the same content repeated 5+ times.

The duplicates are visible in the scroll history (not just a visual flicker). The content below the duplicates is correct — it appears to be a rendering/repaint issue, not actual
duplicate API responses.

Environment (there will likely be a section for this below the fold):

• Claude Code version: 2.1.119
• OS: macOS (Darwin 25.4.0)
• Terminal: macOS Terminal.app (not iTerm2)
• Shell: zsh
• Terminal dimensions: 184×173

What Should Happen?

Each response should render once and append below the previous one.
New tool results should add to the bottom of the output, not cause
the entire conversation to re-render from the top.

Error Messages/Logs

No error messages. The bug is purely visual — no crash, no error output.

Steps to Reproduce

1. Start a Claude Code session in macOS Terminal.app
2. Give Claude a task that requires multiple sequential file edits

in a single response (e.g. "update these 4 sections in this file")

1. Observe the terminal output as each Edit tool call completes
2. The full output block from earlier in the response re-renders

after each tool result, causing it to appear repeated N times
(once per tool call)

Alternative trigger: the very first response in a new session
containing a markdown table may also repeat ~20 times before
the prompt appears.

Claude Model

Sonnet (default)

Is this a regression?

Yes, this worked in a previous version

Last Working Version

_No response_

Claude Code Version

 2.1.119 (Claude Code)

Platform

Anthropic API

Operating System

macOS

Terminal/Shell

Terminal.app (macOS)

Additional Information

<img width="275" height="1219" alt="Image" src="https://github.com/user-attachments/assets/c47cb470-3b62-4d8f-8397-73a86fb431ce" />

<img width="229" height="1225" alt="Image" src="https://github.com/user-attachments/assets/2fde7354-3d1f-4482-bd23-5ececc32dcc7" />

<img width="343" height="1231" alt="Image" src="https://github.com/user-attachments/assets/5d900b8d-168e-432f-be0e-16dff6989a09" />

<img width="293" height="1217" alt="Image" src="https://github.com/user-attachments/assets/07696778-2513-4dab-ac28-31b4c9dff11d" />