[BUG] Claude Remote not dropping sessions

### Preflight Checklist

- [x] I have searched [existing issues](https://github.com/anthropics/claude-code/issues?q=is%3Aissue%20state%3Aopen%20label%3Abug) 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?

Remote Control Session Leak
Platform: Windows 11 + Mobile app

Issue:
Remote Control parent process (PID 12768) spawned 24 child session processes over 7 days (07/09–13/09). None exited when sessions closed. Each child consumed 1–12% CPU; accumulated to 87.5% CPU total.

Separately, phone app shows dozens of sessions with green "active" marker. Persist after app close/reopen. Sessions never marked closed in backend.

Steps to Reproduce:

Enable Remote Control
Open multiple cloud sessions (or use phone app across multiple days)
Close sessions
Check process list (Windows: Get-CimInstance Win32_Process -Filter "ParentProcessId=") or session list (phone)
Expected:
Child session processes exit when session closes. Backend marks session state closed.

Actual:
Child processes orphaned indefinitely. Backend sessions remain "active" forever.

Impact:

CPU stays pegged until manual process kill
Phone account cluttered with zombie sessions
No way to revoke/clear stale remote sessions
Environment:

Claude Code 2.1.267 (Windows CLI)
Windows 11 Pro 22000
Claude mobile app (Android)

### What Should Happen?

Child session processes exit when session closes. Backend marks session state closed.

### Error Messages/Logs

```shell

```

### Steps to Reproduce

Enable Remote Control
Open multiple cloud sessions (or use phone app across multiple days)
Close sessions
Check process list (Windows: Get-CimInstance Win32_Process -Filter "ParentProcessId=") or session list (phone)

### Claude Model

Sonnet (default)

### Is this a regression?

I don't know

### Last Working Version

_No response_

### Claude Code Version

Claude Code 2.1.267 (Windows CLI)

### Platform

Anthropic API

### Operating System

Windows

### Terminal/Shell

Windows Terminal

### Additional Information

_No response_