[BUG] Cowork: yukonSilver reports status=unsupported despite working KVM/vsock — possibly distro-name detection issue on Zorin OS (Ubuntu-based, non-Ubuntu lsb_release)

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

• Device: ThinkPad T14 Gen 2i
• Claude Desktop: 1.24012.11 (Linux beta)
• OS: Zorin OS 18.1 (Ubuntu 24.04/noble base) — lsb_release -a reports Distributor ID Zorin, not Ubuntu
• Kernel: <output of uname -r>
• CPU virtualization: confirmed enabled (egrep -c '(vmx|svm)' /proc/cpuinfo → 16)
• /dev/kvm: crw-rw----+ 1 root kvm 10, 232 — correct ownership/permissions
• User is a member of kvm group (confirmed via groups $USER, logged out/in after adding)

Note: Zorin OS is Ubuntu-based but self-identifies as Zorin rather than Ubuntu in lsb_release//etc/os-release. If yukonSilver's platform check does a literal distro-name match rather than checking the underlying Ubuntu base, this would misclassify a fully Ubuntu-compatible system as unsupported.

What's Wrong?

Cowork fails to initialize with the "Virtualization isn't fully set up" dialog, despite KVM being fully accessible and hardware virtualization confirmed enabled. This matches the yukonSilver platform-detection bug described in #73568, and may be related to the distro-detection gating described in #74605.

Log output (~/.config/Claude/logs/cowork_vm_node.log)

​``
[cleanupVMBundleIfUnsupported] yukonSilver not supported (status=unsupported), checking for stale bundle...
[VM] Loading vmClient (TypeScript) module...
[VM] Module loaded successfully
[linux-vm] Spawning helper: /usr/lib/claude-desktop/resources/cowork-linux-helper
[linux-vm-helper] starting (pid=20356, socket=/run/user/1000/claude-cowork-vm.sock)
[linux-vm-helper] [server] listening on /run/user/1000/claude-cowork-vm.sock
[linux-vm] Helper exited (code=null, signal=SIGHUP)
​`
The helper spawns and binds its socket successfully, but yukonSilver reports status=unsupported` on every launch regardless, and the VM bundle never downloads. The helper process is then killed (SIGHUP) shortly after.

Steps to Reproduce

1. Confirm /dev/kvm permissions and kvm group membership are correct
2. Confirm hardware virtualization is enabled
3. Fully log out and back in
4. Launch Claude Desktop, attempt to start a Cowork task
5. Observe "Virtualization isn't fully set up" dialog despite all prerequisites being met

Expected

Cowork detects working KVM and proceeds to download/boot the VM bundle.

Actual

yukonSilver classifier reports unsupported on every launch; VM never boots.

What Should Happen?

Cowork detects working KVM and proceeds to download/boot the VM bundle.

Error Messages/Logs

Log output (~/.config/Claude/logs/cowork_vm_node.log)
​ [cleanupVMBundleIfUnsupported] yukonSilver not supported (status=unsupported), checking for stale bundle... [VM] Loading vmClient (TypeScript) module... [VM] Module loaded successfully [linux-vm] Spawning helper: /usr/lib/claude-desktop/resources/cowork-linux-helper [linux-vm-helper] starting (pid=20356, socket=/run/user/1000/claude-cowork-vm.sock) [linux-vm-helper] [server] listening on /run/user/1000/claude-cowork-vm.sock [linux-vm] Helper exited (code=null, signal=SIGHUP) ​
The helper spawns and binds its socket successfully, but yukonSilver reports status=unsupported on every launch regardless, and the VM bundle never downloads. The helper process is then killed (SIGHUP) shortly after.

Steps to Reproduce

1. Confirm /dev/kvm permissions and kvm group membership are correct
2. Confirm hardware virtualization is enabled
3. Fully log out and back in
4. Launch Claude Desktop, attempt to start a Cowork task
5. Observe "Virtualization isn't fully set up" dialog despite all prerequisites being met

Claude Model

Sonnet (default)

Is this a regression?

No, this never worked

Last Working Version

_No response_

Claude Code Version

1.24012.11

Platform

Anthropic API

Operating System

Other Linux

Terminal/Shell

Xterm

Additional Information

_No response_