[BUG] Claude in Chrome: controlled tab renders squished in the top-left while a task is running

### Preflight Checklist

- [x] I have searched [existing issues](https://github.com/anthropics/claude-code/issues?q=is%3Aissue%20state%3Aopen%20label%3Abug) 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?

While a scheduled Claude Code task was driving a tab through the Claude in Chrome extension, the page in that tab rendered inside a small, fixed-size frame in the top-left corner of the browser window. The rest of the window stayed blank.

`resize_window` was never called during the run — the task only used `navigate`, `computer` (screenshot / click / scroll), `find` and `read_page`. The tab belongs to the tab group that the extension itself creates.

If the user happens to look at Chrome during an unattended run, it looks like the browser display is broken.

### What Should Happen?

The controlled tab should keep the normal window viewport while it is under automation.

If the extension has to change the rendered size, it should make that state visible to the user (a clear "this tab is being controlled" indication) and restore the original viewport once control ends.

### Error Messages/Logs

```shell

```

### Steps to Reproduce

1. Windows 11 Pro, Chrome with the Claude in Chrome extension, Claude Code desktop app.
2. Start a scheduled task that uses the browser tools.
3. Let the task work in the tab created in the extension's tab group, using only `navigate`, `computer` (screenshot / click / scroll), `find` and `read_page` — never `resize_window`.
4. Look at the Chrome window while the task is running.
5. The page is rendered in a small fixed-size frame in the top-left corner; the rest of the window is blank.

### Claude Model

Not sure / Multiple models

### Is this a regression?

I don't know

### Last Working Version

_No response_

### Claude Code Version

2.2553.0

### Platform

Anthropic API

### Operating System

Windows

### Terminal/Shell

Other

### Additional Information

Observed on 2026-09-18, roughly 23:10-23:31 JST.

On 2026-09-15 a similar squished state remained even after the task had finished, until the tab was closed or Chrome was restarted.

Start with the browser tools used in the scheduled task—navigate, computer, find, and read_page—and observe the extension-created tab group during a run. Done means the controlled tab retains its normal viewport, and any temporary rendered-size state is clearly indicated and restored when control ends.

Written by the indexing model from the issue text.