That resonates a lot.

I’ve noticed the same thing: if the shape of the problem is still interesting after the novelty wears off and progress stalls, that’s usually the real signal. The visible demo work is easy; the hard part is exactly what you said—defining “done,” handling edge cases, and making systems behave consistently under stress. If those invisible constraints keep pulling you back, it’s usually because there’s something fundamentally worth building there.

Exactly. I’ve also found that once those constraints become boring, that’s usually when the work itself is done — or not worth doing anymore.