[BUG] Cowork tab missing - yukonSilver not supported on AMD Ryzen 9800X3D

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?

Environment

• App version: 1.2773.0 (MSIX install via Claude_pzs8sxrjxfjjc)
• OS: Windows x64
• CPU: AMD Ryzen 7 9800X3D
• Install type: MSIX

Prerequisites verified ✅

• Plan: Pro (paid)
• Hyper-V: Enabled (Enable-WindowsOptionalFeature confirmed State=Enabled)
• vmms: Running (Automatic)
• vmcompute: Running (Manual)
• HyperVisorPresent: True
• AMD SVM Mode: Enabled in BIOS (ASUS ROG Strix)
• Virtual Machine Platform: Enabled
• Windows Hypervisor Platform: Enabled
• Feature flags: claudeai_cowork_backend_marketplaces=true, cowork_plugin_host_ops=true

Symptoms

Cowork tab never appears in Claude Desktop. Only Chat and Code tabs are visible.

VM module loads but Cowork tab never appears.

Fixes attempted (all failed)

1. Installed Claude Desktop
2. Enabled Hyper-V via Enable-WindowsOptionalFeature -Online -FeatureName Microsoft-Hyper-V -All
3. Verified vmms and vmcompute services running
4. Enabled AMD SVM Mode in BIOS (ASUS ROG Strix)
5. Confirmed HyperVisorPresent = True via Get-ComputerInfo
6. Full clean reinstall:

• Uninstalled Claude Desktop
• Removed residues: $env:APPDATA\Claude, $env:LOCALAPPDATA\Claude, $env:LOCALAPPDATA\AnthropicClaude, $env:LOCALAPPDATA\Packages\Claude_*
• Restarted Windows
• Fresh install from claude.ai/download

1. Verified MSIX installation is correct (not Squirrel) via logs
2. Confirmed claude_desktop_config.json contains cowork preferences

Actual behavior

yukonSilver platform detection marks configuration as "unsupported" on AMD Ryzen 9800X3D
despite all virtualization requirements being met. Cowork tab never renders.

Related issues

#25136, #27316, #27420, #29887, #45715, #48407

What Should Happen?

Cowork tab should appear alongside Chat and Code tabs.

Error Messages/Logs

2026-04-16 12:59:02 [info] [cleanupVMBundleIfUnsupported] yukonSilver not supported (status=unsupported), checking for stale bundle...
2026-04-16 12:59:43 [info] [VM] Loading vmClient (TypeScript) module...
2026-04-16 12:59:43 [info] [VM] Module loaded successfully

Steps to Reproduce

1) Have a pro plan
2) Install Claude Desktop on AMD system (CPU AMD Ryzen 7 9800X3D)
3) Cowork tab not shown

Claude Model

None

Is this a regression?

I don't know

Last Working Version

_No response_

Claude Code Version

Claude 1.2773.0 (884b37) 2026-04-15T14:32:09.000Z

Platform

Anthropic API

Operating System

Windows

Terminal/Shell

PowerShell

Additional Information

_No response_