Windows: taskkill leaves orphan subprocesses that block Claude Desktop relaunch (0x80070020)

Bug Report

Environment

• OS: Windows 11 Pro 10.0.26200
• Claude Desktop version: 1.8089.1.0 (MSIX/Store package)
• Package: Claude_1.8089.1.0_x64__pzs8sxrjxfjjc

Description

After force-killing Claude Desktop with taskkill /F /IM "Claude.exe", the app refuses to relaunch. Windows throws error 0x80070020 (ERROR_SHARING_VIOLATION) when trying to create a new AppX container.

Root Cause

When the main claude.exe process is killed via taskkill /F, child processes survive:

• cowork-svc.exe (from app/resources/cowork-svc.exe)
• chrome-native-host.exe (Chrome extension bridge)

These orphan processes hold file locks on the MSIX package directory, preventing Windows from creating a new Desktop AppX container for a fresh launch.

Steps to Reproduce

1. Open Claude Desktop (Windows Store/MSIX version)
2. Run taskkill /F /IM "Claude.exe" in an elevated terminal
3. Try to relaunch Claude Desktop from Start menu or taskbar
4. App fails to open — no window appears, no error shown to user

Windows Event Log Evidence

Microsoft-Windows-AppModel-Runtime/Admin:

0x80070020: Cannot create the process for package Claude_1.8089.1.0_x64__pzs8sxrjxfjjc 
because an error was encountered while configuring runtime. [FinishPackageActivation]

0x80070020: Cannot create the Desktop AppX container for package Claude_1.8089.1.0_x64__pzs8sxrjxfjjc 
because an error was encountered converting the job.

Workaround

Manually kill the orphan processes before relaunching:

Get-Process cowork-svc, chrome-native-host -ErrorAction SilentlyContinue | Stop-Process -Force
# Then relaunch Claude Desktop

Expected Behavior

• Child processes (cowork-svc.exe, chrome-native-host.exe) should terminate when the parent claude.exe exits
• OR Claude Desktop should detect and clean up stale subprocesses on launch
• OR the installer should use a Windows Job Object to ensure all child processes are killed when the parent dies

Suggested Fix

Use a Windows Job Object with JOB_OBJECT_LIMIT_KILL_ON_JOB_CLOSE flag to group the main process and all children. This ensures automatic cleanup when the parent process terminates (gracefully or forcefully). This is the standard pattern for Electron/Chromium apps on Windows.

Alternatively, on startup, detect and kill any pre-existing cowork-svc.exe instances from a previous session before initializing the AppX container.

---

Reported via Claude Code CLI