If anyone is curious, some more detail.

The current overarching self-imposed task of reinventing things I know diddly squat about (not the first or last one) is a printer color profile. Using Oklab as a PCS and allowing for more wiggle room than ICCv2.

Obviously, the mapping between Oklab and CMYK is non-uniform and one is a dimension bigger than the other.

I tried reading ArgyllCMS code and didn't understand a thing, not sure if it's because of lack of knowledge or because complex C code just tends to be unreadable.

Either way what I have right now already beats the output of Argyll, so I know it's not entirely a fool's errand. Especially surprising given that I keep finding dumbest mistakes in my calculations and logic ("what do you mean I forgot to ^2 the coordinates in the euclidean distance and it still works?")

This is not a jab at Argyll, we've been relying on it for years now, plus I'm not constrained by an ancient PCS and even being paid (begrudgingly, I feel, but it's a nice break from forms and buttons). And yes I did even get the client to send some money to Argyll dev. Not without having to explain how FOSS works and how badly everything is fucked right now.