Windows: app update fails with 'application already in use' because session background processes survive app exit

Summary

On Windows, updating the Claude desktop app fails with an error like "the application is already in use" when a Claude Code session previously started long-running background processes with the Bash tool (run_in_background). Those child processes (in our case a portable mariadbd.exe and a php -S dev server) survive after the app window is closed, and the updater/relauncher then refuses to start.

Killing the leftover processes fixes the update immediately.

Environment

• Claude desktop app on Windows 11 Pro (build 10.0.26200)
• App version at the time: ~1.21459.x (issue reproduced across several consecutive updates)
• Background processes started by Claude Code sessions via Bash run_in_background: mariadbd.exe (portable MariaDB) and php -S localhost:8123 (dev server)

Steps to reproduce

1. In a Claude Code session (desktop app), have the agent start a long-running background process with the Bash tool (run_in_background: true), e.g. a database server or php -S.
2. Close the desktop app (the background processes keep running — visible in Task Manager).
3. Install a pending app update and relaunch.
4. Launch fails with a message that the application is already in use.

Expected behavior

Either the app should terminate (or offer to terminate) tracked background tasks on exit, or the updater/launcher should not treat those orphaned child processes as "the application in use".

Workaround

Manually killing the leftover processes (mariadbd.exe, php.exe) before updating makes the update work every time.

Notes

Reported on behalf of a non-technical user who hit this on several consecutive updates without knowing the cause; the session's background-task panel showed the tasks as still running ("Tareas en segundo plano") even after app restarts. The user believes other users may be affected. Issue text drafted by Claude Code at the user's request.