Thanks for answer, really just being curious.
Never heard "instant legacy SW", but I know exactly what you mean.
"It's a fixed price contract, no budget for updates. Sad, but normal."
Sadly, I am programming for about 2 decades and I KNOW EXACTLY what you mean by that.
It's better if you just have to give them product and never look back on it, but if you have to keep that code working with occasional change, yeah, that's best way to lunatic asylum.