I make Claude, Codex and Gemini review each other's design plan and implementation. Each always found a lot of things the others missed...until Fable 5 came out. Whatever plan or code Fable 5 comes up with, now it's very hard for Codex and Gemini to find any serious hole in it.
In my experience, audit findings decrease in frequency as a codebase matures. Was Fable doing greenfield work?