Deterministic Time: Don’t Break Ordering and Replay in Distributed Systems

In distributed systems, what we actually want is not “the correct time.” We want two things: Ordering : don’t lose which came first. Replay : later, explain the same decision with the same grounds and procedure. But in real systems we casually lean on created_at (wall clock). And then everything breaks: NTP adjustments / VM migration / suspend-resume makes clocks jump backward or forward Prometheus / logs / warehouse don’t align to the “same 5-minute window” log order collapses → postmortems bec