Windows installer cannot update the app: leftover CoworkVMService is Access Denied even elevated -> AddPackage 0x80073CF9 (machine stuck on a crashing build)

Second, unrelated bug in the same session: installer cannot update the app

Three attempts to reinstall/update tonight (23:37:16, 23:38:26, 23:41:02) all failed identically,
so the app is still on the crashing 1.24012.9 and cannot be updated by the normal installer:

Removing conflicting CoworkVMService...
WARNING: failed to remove conflicting service: could not open CoworkVMService: Access is denied.
Removing: Claude_1.24012.9.0_x64__pzs8sxrjxfjjc
Windows rejected data-preserving removal for Claude_1.24012.9.0_x64__pzs8sxrjxfjjc
  (0x80073CFA, requires developer mode); relying on in-place update
Installing via AddPackage (current-user)...
MSIX installation failed: AddPackage failed: AddPackage failed with HRESULT 0x80073CF9
ERROR dialog (with log path): Administrator access is required to install Claude with full
  features. You can try again or install without Cowork.

The installer runs elevated (Is elevated: true, Elevation type: Full) and the MSIX signature
verifies, yet OpenService on CoworkVMService returns Access Denied — a leftover service from a
previous install that the elevated installer cannot remove, after which AddPackage fails with
0x80073CF9. Conflicting service: true has been logged on every run since 2026-07-25.

The installer's own error dialog says "Please share this log with us" — full log:
C:\Users\joshu\Downloads\ClaudeSetup 3.log (single clean attempt) or ClaudeSetup.log
(full history back to 2026-07-12).

Why this matters beyond the failed install

This machine hits the app-terminating crashes in #81698 (GPU process death, 4 occurrences) and #82460 (PreviewError). Even when a fixed build ships, it cannot arrive: the elevated installer cannot open the leftover CoworkVMService to remove it, so AddPackage fails with 0x80073CF9 every time. Conflicting service: true has appeared in every setup log since 2026-07-25.

At the time of the attempts, latest/redirect resolved to the already-installed 1.24012.9, so nothing was lost tonight — but the update path itself is broken, which turns every future fix into an unreachable one.

Requests

1. Make the installer able to stop/remove its own CoworkVMService (or instruct Windows Installer to skip the data-preserving removal path that requires developer mode).
2. Surface a clearer error — the current dialog suggests retrying as admin, but the installer already runs elevated (Elevation type: Full).

Setup logs preserved locally and available on request (the installer's own dialog asks to share them). Environment: Windows 11 Home 26200, app 1.24012.9 MSIX Claude_pzs8sxrjxfjjc.