> It’s likely it missed some crucial subtlety that will come to bite you in the ass down the line.

Maybe, but that's part of the experience of learning. I plan to maintain pools for the rest of my life, if I made an oversight which costs me down the line then the lesson will be that much more memorable.

This is an above-ground pool with a pump and a filter, the stakes are relatively low. In the absolute worst case I could rip it all out and pay a pro to do it for the price I was quoted.

Human workers also wreck these jobs horribly that come to bite your ass in the end. I think an intelligent person equipped with AI and common sense and real stake in the thing being well done (because it's their own, so they care) is better than whatever is possible to pay for or book in a realistic timeline from another human.

Also, ask people in the trades to review each other's jobs. They will harshly criticize each other too for missing basic things and then go on to vehemently disagree. As an outsider it doesn't mean much that an expert found some fault. They always find something to nitpick.