The Wrong Way Round

Rewrite every DD/MM/YYYY date as YYYY-MM-DD, leaving the rest of the text alone.

Three groups out, three groups back in a different order. Exactly two digits for the day and the month, and they have to be digits — a quantifier loose enough to take any character will cheerfully reorder a file path. Exactly two also has to mean exactly: without a guard on each end, the pattern finds a two-digit date sitting inside a longer run of digits and rewrites half of it. This challenge is about the shape of a date, not its validity — 45/99/2026 has the shape and is nobody's birthday, and pinning real ranges costs far more than it teaches here.