Operator saw the `http` plugin -- deleted when ping/dns/http were unified into the Monitor entity -- still reported as enabled, with no way to clear it. It was never an orphaned row. `plugin.http` was hardcoded in core DEFAULTS, so deleting the app_settings row did nothing: the default reasserted it on the next settings load. That is precisely why no cleanup UI could have fixed it. Rule 22 says the removed subsystem should have taken its setting with it. Purged the surviving references -- the DEFAULTS key, "http" in CAPABILITY_PLUGINS, the stale plugin_manager docstring example, and the capabilities blurb still advertising HTTP/uptime as a bundled capability -- plus a migration dropping any stored plugin.http row. Untouched: `http` as a MONITOR TYPE (icmp/tcp/dns/http) everywhere it appears, and http_001_initial, which is kept deliberately so existing DBs resolve the revision graph. For the general case, cleanup splits by provenance rather than being uniformly automatic or uniformly manual: Bundled plugins ship in the image and version atomically with core, so they cannot be transiently missing -- a plugin.* default with no bundled directory is unambiguously a bug. Guarded by a unit test that fails CI, which is the only part safe to automate. External plugins live in operator-mounted /data/plugins, where absence is ambiguous: unmounted volume, failed install, mid-upgrade. Auto-deleting their config would silently destroy unrecoverable credentials on a transient condition, so Settings now lists them under "Configured but not installed" with an explicit, confirmed, audit-logged Remove. The section hides entirely when empty, and the remove route refuses if the plugin is actually installed. Orphan detection reads STORED rows, never the DEFAULTS-merged view -- offering to remove a default-only key would be a lie -- and returns names only, since plugin config can hold credentials and listing orphans never needs their values. Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>