Deleting the dead deferred renderer left a ghost behind: a GPU classifier whose every caller had just been deleted. This is the short one about chasing a deletion all the way to zero, and about a cost you pay without seeing it. Every line of 'keep it, might be useful later' is load time, memory, and a place for bugs to hide. The engine you run should be exactly the engine that is alive.
Lux had two ways to light a surface, and only one of them was real. The other shaded everything magenta and never drew a frame. Two lighting paths means two ways for your materials to look wrong, so this post deletes the dead one. Now there is exactly one place where light meets a surface, which means every tonemap tweak, every roughness fix, every colour improvement lands in every scene at once. Your gold looks like gold everywhere.
You will never see this commit, and that is the point. The god-file carve is finished, and a CI gate now stops any engine file from crossing 800 lines again. Why it matters to you: a codebase that does not rot is the difference between a tool that gets better every week and one that slows to a crawl, and small, focused files are what keep the per-frame hot path allocation-free when your patch gets big.