[BUG] Content Disappears Using Ultraplan in the Browser

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?

I delegated some work to an Ultraplan session (https://claude.ai/code/session_011trru92KNPXH2axtmEDFoo?from=cli)

Expanding the plan allows me to read plan a little bit easier than docking it on the right side of the page.
<img width="1280" height="1032" alt="Image" src="https://github.com/user-attachments/assets/5408a013-da7f-4e82-9971-15fdb0dd00aa" />

However, after a few moments the plan is dropped from the "fullscreen" view, and it states that there is no plan.
<img width="1280" height="1032" alt="Image" src="https://github.com/user-attachments/assets/59437833-f8ec-4aa7-b445-f0eef5e3be8e" />

Minimizing/docking the plan brings the content back, and I am able to return to full screen mode with the content as well, but this process will repeat, so in a few minutes I will lose the full screen content again.
<img width="1280" height="1032" alt="Image" src="https://github.com/user-attachments/assets/74cc8c1e-fae4-4ea8-b3a3-93a05ed2d65e" />

What Should Happen?

The plan content should not disappear, it should remain on the screen until I choose to dismiss it.

Error Messages/Logs

From my chrome dev console:
shared-0-VcElU0VQ.js:1 [O11Y] [DatadogRUM] Initialized Objectenv: "production"service: "claude-ai"version: "d8ab11fbd8"[[Prototype]]: Object
ad.doubleclick.net/ccm/s/collect?auid=2016292941.1782753453&gtm=45be67l0v9196940227za200zd9196940227xec:1  Failed to load resource: net::ERR_BLOCKED_BY_CLIENT
/api/claude_code/organizations/0ed72e62-37a4-4a59-9bca-686618bf2936/user_settings:1  Failed to load resource: the server responded with a status of 404 ()

No logs from claude are seen on the page (even in the verbose transcript view).

Steps to Reproduce

1. Start a planning session using ultraplan.
2. Claude will provide you with a link to continue on the web, go to that web page.
3. Wait for a claude to propose a plan, it will display in a drawer on the right hand side of the browser window.
4. Expand the drawer containing the plan.
5. Wait a few minutes for the content to disappear

Claude Model

Sonnet (default)

Is this a regression?

I don't know

Last Working Version

_No response_

Claude Code Version

2.1.217

Platform

Anthropic API

Operating System

Windows

Terminal/Shell

PowerShell

Additional Information

_No response_