same, I've been liking https://openspec.dev/ and find the more time I put iterating/scrutinizing the spec artifacts (proposal, requirements, design, tasks) before I let the agent implement the better understanding I have and the better results I get. Also like that it is agent agnostic so I can take it with me as I try different agents/models.

Has there been a time when your spec was accurate, the agent implemented it, everything passed — but you still felt you didn't really understand what was happening? If so, what did you do about it? Did it degrade your ability to make subsequent specs?