My most valuable specs, when coding sans agent, is either a UI sketch, some transition diagrams for logic flows, or a few bullet points of business rules. Then

My most valuable specs, when coding sans agent, is either a UI sketch, some transition diagrams for logic flows, or a few bullet points of business rules. Then coding becomes just a Zen activity. I can get most of it done in one go vibing to my favorite tunes. Then comes the tweaking phase where everything left unspecified get specified. I still don't feel the need for an agent. The writings of the loose specs is either done offline on paper, through rounds of discussions with stakeholders, and/or with a lot of reading. When I'm hit with an error while coding, that's usually a signal that I don't know something and should probably stop to learn about it. When it comes to tweaking, fast feedback is king. I know where the knobs are and checking the adjustment should be quick. So it's mostly tests, linting, or live editing environment.