Function compact_clusters 

pub fn compact_clusters(
    facts: &mut Vec<KnowledgeFact>,
    cfg: &ClusterCompactionConfig,
) -> (usize, Vec<KnowledgeFact>)

Collapse clusters of low-value, mutually-similar, same-category facts into one recoverable digest each. Returns (clusters_collapsed, archived_originals); the caller archives the originals so the operation is lossless. Deterministic: candidates are scanned in the store’s existing order and similarity ties resolve to the earliest-founded cluster.