Function scan_extensions 

pub fn scan_extensions(
    plugins_root: &Path,
    marketplaces_root: &Path,
    config_dir: &Path,
) -> ExtensionScan

Scan the plugin cache and marketplace manifests into per-plugin component inventories, one entry per plugin the registry, a manifest or the cache knows about. Installed plugins scan their registry installPath; uninstalled ones their marketplace clone source. A registry entry with no readable install dir - gone, unreadable, or absent from the entry itself - emits a LoadFailed row carrying its reason rather than disappearing, and so does a marketplace whose manifest could not load.