[BUG] Cowork "yukonSilver not supported" on Windows 11 with Hyper-V + Virtual Machine Platform enabled (physical hardware)

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?

Preflight Checklist

I have searched existing issues — this is similar to #27248 / #25136 / #25142 / #25505 but appears to be a separate machine in the same rollout pattern
This is a single bug report
I am using the latest version of Claude Desktop

Environment

OS: Windows 11, build 26200.8246
Hardware: Physical machine (not a VM, not WSL2, not Docker)
Hyper-V: Active on host OS
Virtual Machine Platform: Confirmed enabled
Account: Cowork-enabled seat
Claude Desktop version: <fill in — Settings → About>

What's Wrong?
Cowork will not load. The persistent error in the Cowork VM logs is yukonSilver not supported (status=unsupported), despite the system meeting every documented hardware and software prerequisite:

Physical hardware (no nested-virtualization detection ambiguity)
Hyper-V is active on the host OS
Virtual Machine Platform Windows feature is confirmed enabled
Account has a Cowork-enabled seat

Anthropic support reviewed the configuration and confirmed the system has the right components, concluding this is a detection bug, not a missing platform capability. Support directed me to file the report here.
This matches the server-side yukonSilver GrowthBook flag rollout pattern documented in #27248 and #25505, where the flag is set to unsupported for specific machines despite meeting all requirements, and has been observed to flip to supported in waves without any user-side change.
Steps to Reproduce

Run Claude Desktop on Windows 11 build 26200.8246 (physical machine, Hyper-V active, Virtual Machine Platform enabled)
Sign in with a Cowork-enabled account
Attempt to open Cowork
Cowork fails to load
%APPDATA%\Claude\logs\cowork_vm_node.log shows persistent yukonSilver not supported entries

Expected Behavior
Cowork loads and is accessible, since all hardware/software requirements are met and the account has a Cowork-enabled seat.
Actual Behavior
Cowork does not load. The server-side yukonSilver flag returns unsupported for this machine across multiple sessions.
Log Output
From %APPDATA%\Claude\logs\cowork_vm_node.log:
<paste 5–10 log lines here showing the "yukonSilver not supported" error, including timestamps>
Related Issues

#27248 — yukonSilver marked unsupported despite meeting requirements; same account works on a different Windows 11 PC (machine-specific rollout)
#25136 — Cowork tab not showing on Windows 11 Pro x64; yukonSilver unsupported
#25142 — Cowork does not show up on Windows 11
#25505 — yukonSilver flipped from "unsupported" to working without user action (server-side wave rollout)

What's Been Tried

Confirmed Hyper-V is active on host OS
Confirmed Virtual Machine Platform Windows feature is enabled
Confirmed the account has a Cowork-enabled seat
Reviewed configuration with Anthropic support, who confirmed the system meets all requirements and directed me to file this bug

Request
Please either (a) push this machine into the supported cohort for the yukonSilver GrowthBook flag, or (b) fix the detection logic so that physical Windows 11 hardware with Hyper-V active and Virtual Machine Platform enabled is correctly identified as supported.

Claude version 1.5354.0 (9a9e3d)

What Should Happen?

Cowork should load in my desktop app

Error Messages/Logs

2026-04-28 21:30:21 [info] [cleanupVMBundleIfUnsupported] yukonSilver not supported (status=unsupported), checking for stale bundle...
2026-04-29 23:11:38 [info] [cleanupVMBundleIfUnsupported] yukonSilver not supported (status=unsupported), checking for stale bundle...
2026-04-30 09:00:53 [info] [cleanupVMBundleIfUnsupported] yukonSilver not supported (status=unsupported), checking for stale bundle...
2026-04-30 09:16:46 [info] [cleanupVMBundleIfUnsupported] yukonSilver not supported (status=unsupported), checking for stale bundle...

Steps to Reproduce

Every time I hover over the cowork icon, it says to reinstall claude

Claude Model

None

Is this a regression?

No, this never worked

Last Working Version

_No response_

Claude Code Version

1.5354.0 (9a9e3d)

Platform

Anthropic API

Operating System

Windows

Terminal/Shell

PowerShell

Additional Information

_No response_