[BUG] Cowork tab flickers and disappears on Linux beta — yukonSilver not supported (status=unsupported), VM bundle never downloads (AMD Ryzen, kernel 6.17)

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:

OS: Ubuntu, kernel 6.17.0-35-generic
CPU: AMD Ryzen 5 4600H; Virtualization: AMD-V; flags include svm, npt, vmcb_clean, sme
systemd-detect-virt: none (bare metal)
kvm-ok: "KVM acceleration can be used"
vsock: vhost_vsock, vsock, vmw_vsock_virtio_transport_common, vhost all loaded
Plan: Max, logged in (past chats + account visible)

Symptom: Cowork tab appears for a fraction of a second on launch, then disappears. [WarmLifecycle:cowork] Initialized → Destroyed on every start.
Root cause from logs (cowork_vm_node.log):
[cleanupVMBundleIfUnsupported] yukonSilver not supported (status=unsupported), checking for stale bundle...
~/.config/Claude/vm_bundles/ is never created — the bundle is judged unsupported before download. The cowork-linux-helper itself spawns and listens on its socket successfully, so the VM plumbing is healthy; the failure is the support-gate rejecting a virtualization-capable AMD host.
Expected: With AMD-V + svm/npt present and KVM working, yukonSilver should be classified supported and the bundle should download.

What Should Happen?

My claude desktop have no cowork tab. I have max subscription

Error Messages/Logs

Steps to Reproduce

You can see error detection and analyze log session with claude chat:
https://claude.ai/share/73d8475d-7ee6-4e52-90a5-16a6df182e6f

Claude Model

None

Is this a regression?

Yes, this worked in a previous version

Last Working Version

_No response_

Claude Code Version

claude-desktop --version 1.17377.1

Platform

Anthropic API

Operating System

Ubuntu/Debian Linux

Terminal/Shell

Other

Additional Information

_No response_