Constant KTSTR_RUN_EPOCH_ENV 

pub const KTSTR_RUN_EPOCH_ENV: &str = "KTSTR_RUN_EPOCH";

Name of the environment variable carrying the cargo ktstr test SESSION EPOCH: nanoseconds since the Unix epoch, stamped ONCE by the orchestrator (cargo_ktstr::run_cargo) before it spawns nextest, inherited by every per-test child process.

test_support::sidecar::pre_clear_run_dir_once uses it as an opaque per-invocation session token: nextest is process-per-test and every test sharing one {kernel}-{project_commit} run directory would otherwise have a later process’s pre-clear delete an earlier peer’s freshly-written {test}-{hash}.ktstr.json (silent stats loss). The first process to clear a dir records this token in a .ktstr_run_epoch sentinel; a later peer whose token matches skips its wipe, sparing the peers’ sidecars. Unset under raw cargo nextest run (no orchestrator) — pre-clear then falls back to its per-process wipe-everything behavior.