[BUG] Recurring "Background security review" notification loop from uninstalled security-guidance plugin — affects multiple unrelated sessions

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?

After installing and later uninstalling the official "security-guidance" plugin, Claude Code started showing a repeating background notification "Background security review found issues" with this error attached, appearing dozens of times with no user action triggering it:

C:\Users\usuario\AppData\Local\Python\pythoncore-3.14-64\python.exe: can't open file 'C:\Users\usuario\AppData\Roaming\Claude\local-agent-mode-sessions\e0075014-9776-46e6-befb-8eee7db87223\37f6c226-b32f-49c1-b308-3690520b56ea\rpm\plugin_01YBNfaNwQztYsnUydt8m47G\hooks\security_reminder_hook.py': [Errno 2] No such file or directory

The referenced file lives in a session-specific temp plugin directory that no longer exists.

What Should Happen?

Uninstalling a plugin should also cancel any of its already-queued background hooks, instead of leaving a dangling reference that retries indefinitely.

Error Messages/Logs

After installing and later uninstalling the official "security-guidance" plugin, Claude Code started showing a repeating background notification "Background security review found issues" with this error attached, appearing dozens of times with no user action triggering it:

C:\Users\usuario\AppData\Local\Python\pythoncore-3.14-64\python.exe: can't open file 'C:\Users\usuario\AppData\Roaming\Claude\local-agent-mode-sessions\e0075014-9776-46e6-befb-8eee7db87223\37f6c226-b32f-49c1-b308-3690520b56ea\rpm\plugin_01YBNfaNwQztYsnUydt8m47G\hooks\security_reminder_hook.py': [Errno 2] No such file or directory

The referenced file lives in a session-specific temp plugin directory that no longer exists.

Steps to Reproduce

1. Install the official "security-guidance" plugin (claude-plugins-official marketplace)
2. Let it run at least once so it schedules a background task
3. Uninstall the plugin (claude plugin uninstall security-guidance)
4. Continue using Claude Code across multiple sessions
5. Observe the "Background security review found issues" notification repeating indefinitely, referencing a now-deleted temp file — it appears even in unrelated sessions with no shared conversation history

Claude Model

None

Is this a regression?

No, this never worked

Last Working Version

_No response_

Claude Code Version

2.1.209 (Claude Code))

Platform

Anthropic API

Operating System

Windows

Terminal/Shell

PowerShell

Additional Information

This also occurred in a completely separate, unrelated conversation with no shared history — suggesting the broken state is tied to the account/installation, not one conversation. At one point it also caused the desktop app to become fully unresponsive across all open windows (Task Manager showed ~87% memory across ~16 Claude processes), requiring a forced process kill to recover.