[BUG] Cowork "Reinstall" button in banner does nothing — "Check for Updates" falsely reports latest version on Windows

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?

Claude Desktop on Windows shows a banner at the top of the app stating "Cowork requires a newer installation" with a "Reinstall" button. However, clicking the Reinstall button does absolutely nothing — no download starts, no installer launches, no error message appears, and the app state doesn't change.

Additionally, using Help → Check for Updates displays a dialog saying "No Update Available — You are running the latest version."
This creates a frustrating dead end: the app tells me I need to reinstall to use Cowork, provides a button to do so, but the button is non-functional — and the update checker contradicts the banner entirely.

This appears to be because my existing installation uses the older Squirrel-based packaging, and the Cowork-enabled build uses MSIX packaging. The in-app updater and Reinstall button only check the Squirrel update channel, which has no knowledge of the MSIX version.

Note: Filing here as there is no dedicated Claude Desktop repository.

What Should Happen?

Clicking the "Reinstall" button in the Cowork banner should either:

Download and run the new MSIX-based installer automatically, handling the Squirrel → MSIX migration, or
Open the browser to claude.ai/download with clear instructions, or
At minimum, display a message explaining that a manual download is required and link to the download page

The "Check for Updates" feature should also be aware that a newer MSIX build exists and not falsely report that the current Squirrel build is the latest version.

Error Messages/Logs

No error messages are shown at all. The Reinstall button silently does nothing. The update checker shows:

"No Update Available
You are running the latest version."

Steps to Reproduce

Steps to Reproduce

1) Have an existing Squirrel-based Claude Desktop installation on Windows (installed before Feb 10, 2026)
2) Open Claude Desktop — observe the banner: "Cowork requires a newer installation" with a "Reinstall" button
3) Click the "Reinstall" button — nothing happens
4) Go to Help → Check for Updates — dialog says "No Update Available — You are running the latest version"
5) Note that claude.ai/download has a newer Cowork-enabled installer available

Claude Model

Opus

Is this a regression?

I don't know

Last Working Version

_No response_

Claude Code Version

N/A — this is a Claude Desktop issue, not Claude Code.

Platform

Anthropic API

Operating System

Windows

Terminal/Shell

PowerShell

Additional Information

-This is related to #25313 (in-app updater doesn't deliver Cowork build) and #25162 (Squirrel-to-MSIX upgrade silently fails), but neither of those specifically address the Reinstall button in the Cowork banner doing nothing with zero feedback to the user.

-The only known workaround is a full manual uninstall → cleanup → fresh download from claude.ai/download → reinstall, which risks disrupting local MCP server configurations and desktop extensions.

-This likely affects all Windows users who installed Claude Desktop before the Cowork launch on Feb 10, 2026.

<img width="332" height="247" alt="Image" src="https://github.com/user-attachments/assets/7d3e8e43-08a0-4278-b9a5-28d08d88216f" />