Reference for Jepsen-style distributed-systems testing - consistency models hierarchy (linearizability vs sequential vs causal vs monotonic-reads vs eventual), nemesis primitives (network partitions, clock skew, kill nodes), workload generators, Knossos + Elle linearizability checkers. Reference-only because Jepsen tests are typically Clojure-bespoke per system; use this skill to evaluate vendor claims and structure your own test. Use when a datastore vendor advertises a consistency guarantee that has to be checked before adoption, when reading a published Jepsen report for gaps, or when a custom replicated store needs its own consistency test scoped.