Stale plugins from removed marketplaces still appear in /plugins menu

Description

After removing custom marketplaces, their plugins still appear in the /plugins interactive menu with "failed to load" errors, but cannot be removed through any CLI command or local config cleanup.

What I see in /plugins menu

❯ claude-nights-watch Plugin · claude-nights-watch-marketplace · ✘ failed to load · 1 error
  matrix Plugin · matrix-marketplace · ✘ failed to load · 1 error

What I've tried

All local config files are clean:

• ~/.claude/plugins/installed_plugins.json → {"version": 2, "plugins": {}}
• ~/.claude/plugins/known_marketplaces.json → only claude-plugins-official
• ~/.claude/plugins/marketplaces/ → only claude-plugins-official/ directory
• ~/.claude/settings.json → {"enabledPlugins": {}}
• Grepped all JSON files under ~/.claude/ for "nights-watch" and "matrix" — no hits in any config file (only in debug logs and session history)

CLI commands also fail:

$ claude plugin list
No plugins installed.

$ claude plugin marketplace list
  ❯ claude-plugins-official (only one)

$ claude plugin uninstall claude-nights-watch
✘ Failed to uninstall plugin "claude-nights-watch": Plugin "claude-nights-watch" not found in installed plugins

$ claude plugin marketplace remove claude-nights-watch-marketplace
✘ Failed to remove marketplace: Marketplace 'claude-nights-watch-marketplace' not found

$ claude plugin marketplace remove matrix-marketplace
✘ Failed to remove marketplace: Marketplace 'matrix-marketplace' not found

Expected behavior

Plugins from removed marketplaces should either:

1. Be automatically cleaned up when their marketplace is removed
2. Be removable via claude plugin uninstall even if the marketplace no longer exists

Environment

• Claude Code CLI (latest)
• Linux