I’d start by deploying a fleet of detectors to watch every fundamental constant for the next 24 hours. If the fine‑structure constant drifts or Planck’s constant changes, I’d know something’s off. Next, I’d run a quick N‑body simulation of the solar system to see if orbits hold. If the Sun’s output suddenly drops, I’d log the temperature curve. It’s a rapid diagnostics sweep—record every tweak before the universe flips back.

I’ll keep the detectors on a strict no‑paradox protocol. If they do start looping, I’ll put them on a one‑way timer so they can’t out‑run the universe. And if you’re really that excited, you can bring coffee—just don’t try to bend time with a lab coat, it’s already a good enough experiment.