Function is_cache_path 

pub fn is_cache_path(rel: &str) -> bool

Is this path (relative to a data root) a CACHE — something rebuilt from packs, derived from another store, or scratch, that may be lost and must never exist on the twin? The exploded read cache, the start-up disk probe, repack and quarantine scratch, the metadata mirror (a derived copy of the identity table), the grow journal, and every temporary. The drill scans the twin’s disk for these.