The point about cached preflights is easy to miss: an attempt with no new OPTIONS entry looks like "no preflight needed" at first glance. When you need to pin down the stage, do you reproduce in a fresh profile or private window so the preflight cache starts empty, or is there a more reliable way to tell from the original capture?

Agree on keeping replacement origins consistent too. Anonymizing two same-origin hosts into different placeholders would invent a CORS problem that was never there.