Definitely Not All Cases

The moment someone claims their regex handles "all edge cases perfectly" is when experienced developers reach for the doubt button faster than they reach for coffee on Monday morning. That innocent little pattern is probably hiding six different ways to break your production server when someone inputs an emoji, a null byte, or—heaven forbid—actual human language with accents. The confidence of regex authors is inversely proportional to the number of Stack Overflow tabs they'll need open tomorrow.