[BUG] Cowork: Squirrel auto-update to v1.1.3963 does not deliver @ant/claude-swift — requires full reinstall to fix #27316

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?

After the fix for #27316 shipped in v1.1.3963, the Cowork tab continued to show "Virtualization is not enabled" on a fully capable Windows 11 Pro system when using the Squirrel installer (.exe from claude.ai/download). The yukonSilver platform detection remained unsupported and the @ant/claude-swift native module was missing from the installed package. The VM bundle was never downloaded, CoworkVMService was never created, and rootfs.vhdx was never provisioned.

A full uninstall → clean of %APPDATA%\Claude and %LOCALAPPDATA%\AnthropicClaude → reinstall of v1.1.3963 resolved the detection issue and the Cowork tab became functional. This suggests the auto-update path for the Squirrel installer does not correctly deliver the @ant/claude-swift module that was added to fix #27316 — a clean install is required.

Evidence: Before Reinstall

The @ant/claude-swift module was completely absent from the app directory. The only native addon present was claude-native-binding.node:

PS> Get-ChildItem "...\AnthropicClaude\app-1.1.3963" -Recurse -Filter "*swift*"

    Directory: ...\AnthropicClaude\app-1.1.3963

Mode                 LastWriteTime         Length Name
----                 -------------         ------ ----
-a----         2/22/2026  11:34 AM        5644112 vk_swiftshader.dll
-a----         2/22/2026  11:34 AM            106 vk_swiftshader_icd.json

PS> Get-ChildItem "...\AnthropicClaude\app-1.1.3963" -Recurse -Filter "*.node"

    Directory: ...\app.asar.unpacked\node_modules\@ant\claude-native

Mode                 LastWriteTime         Length Name
----                 -------------         ------ ----
-a----         2/22/2026  11:34 AM         650576 claude-native-binding.node

No @ant/claude-swift directory or .node file existed anywhere in the install tree.

Logs showed a continuous loop with no recovery path:

2026-02-22 11:43:48 [info] [cleanupVMBundleIfUnsupported] yukonSilver not supported (status=unsupported), checking for stale bundle...
2026-02-22 11:43:51 [warn] [startVM] VM not supported (win32/x64), skipping
2026-02-22 11:43:51 [error] [Callbacks] Swift VM addon not available for callbacks
2026-02-22 11:44:59 [info] [cleanupVMBundleIfUnsupported] yukonSilver not supported (status=unsupported), checking for stale bundle...
2026-02-22 11:45:03 [warn] [startVM] VM not supported (win32/x64), skipping
2026-02-22 11:45:03 [error] [Callbacks] Swift VM addon not available for callbacks
2026-02-22 11:45:25 [info] [Bundle:status] rootfs.vhdx missing

All downstream artifacts were absent:

PS> sc query CoworkVMService
# (no output — service does not exist)

PS> ls "$env:APPDATA\Claude\vm_bundles\claudevm.bundle\"
# (no output — directory empty)

Environment (confirmed fully capable)

• Claude Desktop version: 1.1.3963 (Squirrel/.exe installer)
• OS: Windows 11 Pro 25H2 (Build 26200.7840)
• Hyper-V: Enabled (Get-WindowsOptionalFeature → State: Enabled)
• vmcompute: Running
• vmms: Running
• VT-x: Enabled in BIOS (Intel Virtualization Technology set to ON)
• systeminfo: "A hypervisor has been detected"

Note: (Get-CimInstance Win32_Processor).VirtualizationFirmwareEnabled returns False, but this is a known false negative when a hypervisor is already loaded — it does not indicate a real problem.

What Should Happen?

The auto-update from a pre-fix version to v1.1.3963 should deliver the @ant/claude-swift native module without requiring a full uninstall/reinstall cycle.

Error Messages/Logs

Steps to Reproduce

1. Have Claude Desktop installed via the Squirrel installer (.exe from claude.ai/download) from before the #27316 fix
2. Allow auto-update to v1.1.3963
3. Open Claude Desktop → Cowork tab
4. Observe "Virtualization is not enabled" error
5. Confirm @ant/claude-swift is missing from the app directory
6. Perform full uninstall → delete %APPDATA%\Claude and %LOCALAPPDATA%\AnthropicClaude → reinstall
7. Cowork tab now works

Claude Model

Opus

Is this a regression?

No, this never worked

Last Working Version

_No response_

Claude Code Version

1.1.3963

Platform

Anthropic API

Operating System

Windows

Terminal/Shell

PowerShell

Additional Information

The fix for #27316 appears to work correctly on clean installs of v1.1.3963. The issue is specifically that the Squirrel auto-update does not add the new native module to existing installations. Users who were affected by #27316 and received the auto-update will remain broken unless they manually uninstall and reinstall.