Spec-first agent workflow retrofits netplay into an existing game

i just shipped netplay in a game whose architecture was never planned to accommodate it. my time was split as follows: 3-4 days of grilling frontier models on the problem space and drafting the spec. over this time i found good answers to every single problem and my skepticism gradually dissolved. i went from "it's impossible for it to play well with 500 active entities to sync" to "it may be actually feasible and even rather cheap and it would play well even across continents". it's a bespoke design that fits this game specifically, it reuses the strong parts about my previous rearchitecture and it's stripped to the core, reusing as much of the existing game machinery. 1 full day of opus implementing the spec, along with multiple rounds of reviews by other models (sol, argon). i used ultra effort and everything worked flawlessly when it was done. this differs quite a lot from multiple previous attempts to add netplay where things went wrong and i got stuck with nasty debugging. this time i put much more human effort (asking the right questions) upfront and got an amazing result.