Cowork install fails — leftover CoworkVMService blocks reinstall, ACL denies delete even under elevated admin

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: Windows 11
Claude Desktop: latest installer (redownloaded fresh, same result)

Problem:
Cowork installation fails with: "Administrator access is required to install Claude with full features. You can try again or install without Cowork." This occurred on first install and persisted after redownloading the installer.
Diagnostics performed:

Get-Service CoworkVMService → service already exists and is Running, despite the failed install.
Attempted Stop-Service CoworkVMService -Force (elevated PowerShell) → succeeded.
Attempted sc.exe delete CoworkVMService (same elevated session) → failed: "OpenService FAILED 5: Access is denied."
Checked the service ACL via sc.exe sdshow CoworkVMService:

D:(A;;CCLCSWRPWPDTLOCRRC;;;AU)(A;;CCDCLCSWRPWPDTLOCRSDRCWDWO;;;S-1-5-80-1949724575-2387902436-65106593-1201171665-3968604)S:(AU;FA;CCDCLCSWRPWPDTLOCRSDRCWDWO;;;WD)
The ACL grants control only to Authenticated Users (limited) and a specific service SID — not to Administrators, which explains the delete failure even with full elevation.

1. Diagnostic log saved locally at: C:\Users\jvig2\AppData\Local\Temp\ClaudeSetup.log

Result: Unable to remove the stuck service through normal means (service control or registry, since takeown doesn't apply to registry paths). This appears to be the same root cause as existing reports (issues #49540, #48437) — HRESULT 0x80073CF6, "Cowork requires administrator privileges to install" despite confirmed full elevation.
Ask: The installer should not leave a service in this state on failure, and/or the uninstaller should be able to clean it up without requiring manual registry ACL edits.

What Should Happen?

.

Error Messages/Logs

Steps to Reproduce

.

Claude Model

None

Is this a regression?

Yes, this worked in a previous version

Last Working Version

_No response_

Claude Code Version

.

Platform

Anthropic API

Operating System

macOS

Terminal/Shell

PowerShell

Additional Information

_No response_