[BUG] Cowork tab not showing on Windows 11 Pro x64 — tab completely absent from navigation

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?

The Cowork tab is completely missing from the Claude Desktop application. Only "Chat" and "Code" tabs are visible in the top navigation. No error message is displayed — the tab is simply not there.

I have tried a full uninstall, manual cleanup of %APPDATA%\Claude and %LOCALAPPDATA%\Claude, PowerShell cleanup of Claude_* packages, and a fresh reinstall with Administrator privileges. Multiple reboots performed. Issue persists after every attempt.

Environment: Windows 11 Professional x64, latest Claude Desktop version, paid subscription.

What Should Happen?

The Cowork tab should appear alongside "Chat" and "Code" in the top navigation bar of the Claude Desktop app, as it does for other paid subscribers.

Error Messages/Logs

No error message is displayed. The tab is simply absent.
This appears to match the yukonSilver platform detection bug reported in issues #25136, #47327, #48407, #49748.

Steps to Reproduce

1. Install latest Claude Desktop from claude.com/download on Windows 11 Pro x64
2. Launch the application with Administrator privileges
3. Log in with a paid account (Pro/Max)
4. Observe: only "Chat" and "Code" tabs are visible — no "Cowork" tab appears

Claude Model

None

Is this a regression?

No, this never worked

Last Working Version

_No response_

Claude Code Version

1.3109.0.0

Platform

Anthropic API

Operating System

Windows

Terminal/Shell

Terminal.app (macOS)

Additional Information

_No response_