Long-duration soaks + real observability = honest results. I walk through writing tests that answer decisions (“Done when X, measured by Y, observed in Z”), building minimal dashboards and golden logs, and running fault injection inside the soak. We tie it to the Systems Engineering V—verifying requirements at the lowest feasible level—so integration becomes confirmation, not a rescue mission. Copy-pasteable plans, pass/fail gates, and rollback/go-no-go you can use Monday.