When and how to add scenarios, chaos events, and invariants to the personhog e2e test harness (rust/personhog-test-harness). Use after fixing a bug or regression in the personhog leader path (leader, router, writer, replica, coordination protocol) so the fix gets a permanent regression scenario; when adding a new failure mode to test (crashes, drains, zombies, lag, failover); or when a new correctness property needs asserting during runs. Trigger terms: personhog gate, chaos scenario, test harness, leader path regression, handoff bug, eviction, writer lag, acked write.