[BUG] Windows MSIX auto-update corrupts package (Modified, NeedsRemediation) - app unlaunchable, Repair fails

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?

Claude Desktop on Windows refuses to launch: "You'll need to go to advanced options and select Repair". Get-AppxPackage shows Status: Modified, NeedsRemediation after a background auto-update (1.25927.0.0 -> 1.26832.0.0). This happened 5+ times between Aug 5-7 2026 (twice in one day). Smart App Control is OFF, so it is not SAC blocking. Settings > Repair fails ("Could not repair the app. Try again."), Reset does not help, and re-registering via Add-AppxPackage -DisableDevelopmentMode -Register AppXManifest.xml runs without error but Status stays Modified. The only recovery is: kill claude/cowork processes, Remove-AppxPackage, reboot (skipping the reboot causes 0x80073CF6 on reinstall), then fresh install from claude.com/download - which lasts only until the next auto-update breaks it again.

What Should Happen?

Auto-update should never leave the MSIX package in Modified/NeedsRemediation state. The updater should defer until the app and background services are fully stopped (or self-heal a modified package), so the app keeps launching after every update.

Error Messages/Logs

Get-AppxPackage *Claude* -> Status : Modified, NeedsRemediation
Settings > Advanced options > Repair -> "Could not repair the app. Try again."
Reinstall without reboot -> Installation failed: AddPackage failed with HRESULT 0x80073CF6

Steps to Reproduce

1. Install Claude Desktop (MSIX) from claude.com/download on Windows 11 x64
2. Use it normally and leave it running in the tray for a day or two
3. A background auto-update runs
4. Try to launch the app: Windows blocks it; Get-AppxPackage shows Modified, NeedsRemediation

Claude Model

_No response_

Is this a regression?

Yes, this worked in a previous version

Last Working Version

1.25927.0.0 (each version works until its own auto-update corrupts it)

Claude Code Version

1.26832.0.0 (Claude Desktop MSIX, Claude_1.26832.0.0_x64__pzs8sxrjxfjjc)

Platform

Other

Operating System

Windows

Terminal/Shell

PowerShell

Additional Information

Impact: effectively unusable for a non-technical user - requires a PowerShell uninstall + reboot + reinstall cycle every 1-2 days. Possibly related: #83932, #63397, #57221, #76357 (update deploying while claude.exe/CoworkVMService are still running).