Arriving From a Learn to Write Code Lesson? The Practice Set Now Says So
A practice set page now greets you by name when you followed a lesson's "Practice this on Coders Rock" link.
Every Learn to Write Code lesson carries a "Practice this on Coders Rock →" link that sends a per-lesson identifier along with it. Follow one of those links now and the matching practice set here shows a banner acknowledging where you came from: "Continuing from Learn to Write Code -- this set practices the lesson you just read."
That's deliberately the whole feature. The set you land on already matches the lesson you just read -- their slugs line up one to one -- so acknowledging the handoff was the missing piece, not the routing. Nothing about the visit is stored anywhere: the banner reads the identifier straight out of the page's own URL for that one pageview and nothing else, which is as far as this site's own rules about not storing anything let a feature like this go without a separate decision to change them.
Everything above runs in this page, on your own machine. There is more of it on the practice pages.