[BUG] Claude Code desktop app (Windows MSIX): idle stealth update quits app, child process survives, register fails 0x80073D02, app unlaunchable until hidden process is killed

### Preflight Checklist

- [x] I have searched existing issues and this hasn't been reported yet (this is a refile of #63397, which the triage bot auto-closed as off-topic and locked; its close message asks for a new issue if still relevant)
- [x] This is a single bug report
- [x] I am using the latest version of Claude Code

### What's Wrong?

This is about the Claude Code desktop app for Windows (the MSIX build that hosts Claude Code sessions). When it wedges as described below, all Claude Code work on the machine is blocked until the manual recovery is done.

The idle "stealth update" quits the app to apply a staged package, but a Claude child process survives the quit. The MSIX register then fails with 0x80073D02 ("Unable to install because the following apps need to be closed"). This leaves the app unlaunchable: clicking the icon does nothing, no window appears, and nothing shows under Apps in Task Manager. Windows suggests the Settings > Apps > Repair flow. Repair also fails with the same 0x80073D02 (the surviving process still holds the package), but the failed repair makes the hidden process visible in Task Manager. Ending that task lets the registration complete and the app launches normally.

This has hit the same machine three days in a row (8/20, 8/24, 8/25).

### What Should Happen?

The stealth update should wait for the full Claude process tree to exit (or use `-ForceTargetApplicationShutdown` semantics) before registering the package, so the register cannot race the app's own surviving children. The app should relaunch normally after an update with no manual recovery.

### Error Messages/Logs

`%APPDATA%\Claude\logs\main.log` ends at the stealth update on 8/20 and never resumes:

```
2026-08-20 17:39:13 [info] [updater] Staged version 1.34493.0 is still current (latest: 1.34493.0, lastTarget: null)
2026-08-20 17:46:13 [info] [stealth-update] Triggering stealth update after idle timeout
2026-08-20 17:46:13 [info] beforeQuitForUpdate handler fired, going down for update
2026-08-20 17:46:13 [info] Windows session ending (close-app) - quitting the app
```

`Microsoft-Windows-AppXDeploymentServer/Operational` shows the register failing repeatedly (each cluster is one manual recovery cycle: launch fails, repair fails, end hidden task, relaunch works):

```
8/24/2026 9:23:11 AM 419 error 0x80073D02: Unable to install because the following apps need to be closed Claude_1.34493.1.0_x64__pzs8sxrjxfjjc.
8/24/2026 9:23:11 AM 401 Deployment Register operation ... failed with error 0x80073D02.
8/25/2026 10:31:32 AM 419 error 0x80073D02: Unable to install because the following apps need to be closed Claude_1.34493.1.0_x64__pzs8sxrjxfjjc.
8/25/2026 10:41:41 AM 419 error 0x80073D02: Unable to install because the following apps need to be closed Claude_1.34493.1.0_x64__pzs8sxrjxfjjc.
```

The 10:41:41 failure is 7 seconds before the successful relaunch at 10:41:48, immediately after ending the hidden process. Accompanying events each time: 404, 401, 8104 (Trust Label, 0x80070057), 8107. Package status after manual recovery is `Ok` (`Get-AppxPackage Claude`), so the package itself is fine; the failure is the register racing the app's own surviving process.

### Steps to Reproduce

1. Run the Claude desktop app on Windows (sideloaded MSIX) with an update staged.
2. Leave the app idle until the stealth updater fires (`[stealth-update] Triggering stealth update after idle timeout` in main.log).
3. The app quits itself for the update. A child process survives the quit.
4. MSIX register fails with 0x80073D02. The app icon now does nothing and no process is visible under Apps.
5. Settings > Apps > Claude > Repair fails with the same error, but the surviving process becomes visible in Task Manager afterward.
6. End the task, launch the app, everything works until the next stealth update.

User-side workaround that skips the repair dance: `Get-Process claude | Stop-Process -Force`, then launch normally.

### Claude Model

Other (Fable 5)

### Is this a regression?

I don't know

### Claude Code Version

2.1.220 (Claude Code), desktop app 1.34493.1.0 (MSIX, package family `Claude_pzs8sxrjxfjjc`)

### Platform

Anthropic API (claude.ai account via desktop app)

### Operating System

Windows (11 Home, build 10.0.26200)

### Terminal/Shell

Other (Claude Code desktop app)

### Additional Information

- Refile of #63397: same race, same error code, closed by the triage bot as "doesn't appear to be about Claude Code" without human review, now locked.
- #84992 / #81698 / #80444 reach a similar stuck-package end state via a GPU crash instead of the updater; different trigger, related cleanup problem (surviving processes holding the package).
- #42776 describes an orphaned process holding a file lock on relaunch.
- Install location: `C:\Program Files\WindowsApps\Claude_1.34493.1.0_x64__pzs8sxrjxfjjc`

The issue names %APPDATA%\Claude\logs\main.log and the [stealth-update] and beforeQuitForUpdate entries; start by tracing that update path and reproducing an idle staged update on Windows. Done means the full Claude process tree exits before MSIX registration, 0x80073D02 does not recur, and the app relaunches without manual process termination.

Scritto dal modello di indicizzazione a partire dal testo della issue.