Function enrich_clusters 

pub fn enrich_clusters(
    clusters: &mut [Cluster],
    commits: &[Commit],
    source_slugs: &[Option<String>],
    client: &GhClient,
    caches: &mut Caches,
    verbose: bool,
)

Fill in login / avatar_url on clusters. Noreply emails resolve offline; the rest are looked up via the commits API (one representative commit per cluster), in parallel. source_slugs maps a commit’s src index to the owner/repo slug to query (or None for non-GitHub sources).