I guess. I think of it more like overriding an existing thing with another for a given scope/time/test, whereas this is providing an implementation for a thing which exists only as a stub.

Maybe it 'counts', I'm not meaning to be picky about the term, my point is more like even if this works by monkeypatching, I wouldn't personally use the term for the product which does something else by those means, if that makes sense? MonkeyLLM or MonkAIpatch or something, sure.

The other comment with a 'list comprehension' example puts it well I think.

(Seeing as you asked for name suggestions elsewhere, I think I prefer the 'stub' theme: Stubby, StubAI, Stubmonkey if you like monkeys/wanted an easier logo, something like that.)