As I do not think this currently is possible, this is a request (maybe we could add a request tag?).
Currently gather.town urls accept a spawn token ID as a prop in the URL. As a previous discussion outlined, there isn’t really a way to access the spawn token, or even know a spawn token was passed.
Having the ability to access these props in the Websocket would open up a number of new and interesting use cases (such as handoffs of information between spaces via portal tiles). You could also start using props to track how someone joined your space (ie ?clicksource=“myhomepage.com”) so you could track how a space was getting traffic.
(And yes, there is a very hacky way to do this now, but the UX on it is not my favorite)