[BUG] Cowork tab silently disappears after uninstalling Hyper-V / Virtual Machine Platform — no error shown (Windows 11 Pro)

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 silently disappeared from the Claude Desktop sidebar after I uninstalled the Hyper-V and Virtual Machine Platform Windows optional features to reclaim resources on a mini-PC. There is no error message, warning banner, tooltip, or notification of any kind. The tab is just gone.
Related issues (#27316, #31991, #24918) show that when virtualisation is missing at first launch, Claude Desktop surfaces an explicit "Virtualization is not enabled" message with guidance. That path does not appear to trigger when the prerequisites are removed from a previously-working installation. The tab is pulled without explanation, and the user has no in-app way to discover why.
From a user's perspective, this is indistinguishable from Anthropic having rolled the feature back or pulled it from their plan.

What Should Happen?

Either of:

The Cowork tab remains visible and, when clicked, shows the same "Virtualization is not enabled" guidance that first-launch users see, pointing at the missing Windows features.
A one-time notification at Claude Desktop startup explains that Cowork has been disabled because required Windows features were removed, with a link or instruction to re-enable Hyper-V and Virtual Machine Platform.

Either behaviour closes the discoverability gap.

Error Messages/Logs

None. The absence of any error is the bug.

Steps to Reproduce

On Windows 11 Pro with Hyper-V and Virtual Machine Platform enabled, install the latest Claude Desktop. Sign in on a paid plan. Confirm the Cowork tab appears in the sidebar and functions normally.
Open "Turn Windows features on or off". Uncheck "Hyper-V" (both the platform and management tools) and "Virtual Machine Platform". Apply and restart when prompted.
After reboot, launch Claude Desktop.
Observe: Cowork tab no longer appears in the sidebar. No error, banner, or notification is shown.

Claude Model

Not sure / Multiple models

Is this a regression?

I don't know

Last Working Version

_No response_

Claude Code Version

N/A — this bug is in Claude Desktop for Windows, version 1.3109.0 (35cbf6), not the Claude Code CLI. Filing here because the repo appears to be the intake point for Cowork bugs (per #27316, #31991, #24918).

Platform

Anthropic API

Operating System

Windows

Terminal/Shell

Other

Additional Information

Claude Model
N/A — this is a Desktop client UI / capability-detection bug, not a model-specific issue.

Is this a regression?
Not a Claude version regression. Cowork worked on this machine on the same Claude Desktop version before the Windows features were uninstalled. The regression is in environment state, not in Claude's release history.

Last Working Version
N/A — see above.

Claude Code Version
N/A — this bug is in Claude Desktop for Windows, version 1.3109.0 (35cbf6), not the Claude Code CLI. Filing here because the repo appears to be the intake point for Cowork bugs (per #27316, #31991, #24918).

Platform
Claude Desktop (Windows). Select the closest available option in the dropdown, or leave on default if "Claude Desktop" is not a choice.

Operating System
Windows 11 Pro, Version 25H2, OS Build 26200.6899.

Terminal/Shell
N/A — Desktop app, not CLI. PowerShell 5.1 was used for the diagnostic commands referenced below, but is not involved in the bug itself.

Additional Information
Hardware: Ryzen AI Max+ 395, 128 GB unified RAM, mini-PC form factor.
BIOS virtualisation: Enabled. Confirmed in Task Manager → Performance → CPU → "Virtualization: Enabled". This is not a BIOS-level misconfiguration.
WSL state:
PS C:\Users\puiu> wsl --status
The Windows Subsystem for Linux is not installed. You can install by running 'wsl.exe --install'.

PS C:\Users\puiu> Test-Path "HKLM:\SOFTWARE\Microsoft\Windows\CurrentVersion\Lxss"
True

PS C:\Users\puiu> Get-ChildItem "HKLM:\SOFTWARE\Microsoft\Windows\CurrentVersion\Lxss"
(no output — key exists but has no subkeys)
WSL was never fully installed on this machine (no distro was ever registered).
Historical system modifications: This machine has been run through Windows slimming tools over time (OOSU10, Winaero Tweaker). These can disable telemetry, WMI endpoints, and non-essential services. Flagging for triage in case Claude Desktop's capability probe relies on a service or API that these tools commonly disable, as this could be a contributing factor to the silent-failure path rather than an explicit-error path.
Repro machine note: This is specifically Windows 11 Pro, not Home, so the Hyper-V availability constraint affecting #31991 does not apply here. Hyper-V was available and was deliberately removed by the user.