In absence of a better answer, I would say that a system has a world-model if it can answer various questions about the world mostly coherently (i.e. the answers to two different questions should not make completely different assumptions about something).
https://arxiv.org/pdf/1803.10122 I have a similar question and found this paper source. One thing I am not sure of is if this is no longer the same concept/close enough concept that people currently talk about, nor if this is the origin.
https://www.sciencedirect.com/science/article/pii/S0893608022001150 This paper seems to suggest something at least about multimodal perception with reinforcement learning/agent type of set up.
I have seen the concept of world-model used to talk loosely about a neural networks or an agents understanding of the world, but I was wondering what resources (blog posts, journal articles, etc.) exist that talk more precisely about what is a world-model, what are its parts, how do you know if a given system has one or not, if a system does have one, how do you know its structure, does a system necessarily even have a world-model to begin with, even if it's a trivial one? etc.?
Thanks!