Browser pane tool fails on all read/screenshot calls with "Policy check temporarily unavailable"

### 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?

The in-app "side browser" pane (Claude Browser tool) opens and connects fine — tab-context checks succeed — but every call that reads or views page content (screenshot, get_page_text, read_page, find) fails immediately with:

"Policy check temporarily unavailable; retry."

This has persisted for ~24 hours across multiple sessions. A full restart of the Claude Code desktop app did not resolve it (the app restart did clear a separate symptom where the pane was stuck showing a stale page, but the underlying read/screenshot error remains identical after restart).

Platform: Windows 11 Pro
Claude Code: desktop app

### What Should Happen?

The browser tool should be able to take a screenshot or read the page content instead of failing immediately.

### Error Messages/Logs

```shell
Policy check temporarily unavailable; retry.
```

### Steps to Reproduce

1. Open the Claude Browser pane / navigate to any page
2. Call any read/view action (screenshot, get_page_text, read_page, find)
3. Error returned immediately every time

### Claude Model

Sonnet (default)

### Is this a regression?

I don't know

### Last Working Version

_No response_

### Claude Code Version

1.46388.3.0

### Platform

Anthropic API

### Operating System

Windows

### Terminal/Shell

Windows Terminal

### Additional Information

_No response_

Start by reproducing on Windows 11 with Claude Code desktop app 1.46388.3.0, using the browser pane actions named in the issue: screenshot, get_page_text, read_page, and find. Then trace where the message "Policy check temporarily unavailable; retry." is returned for browser read/view calls. Done means those actions can read or view page content instead of failing immediately, or the failure is narrowed to the external policy check.

由索引模型根据 Issue 内容生成。