Shortly we'll be releasing 'The Manual of Design Fiction' ( https://nearfuturelaboratory.myshopify.com/products/the-manual-of-design-fiction )

Design Fiction is described in this essay here: https://shop.nearfuturelaboratory.com/products/design-fiction-a-short-essay-on-design-science-fact-and-fiction

Effectively it's creating objects from a possible future, whereas most science-fiction writes stories, Design Fiction makes material artifacts that imply aspects of a possible future/adjacent world. I'll admit that 'diegetic prototype' sounds opaque. It simply suggest that the notion of a prototype (a made artifact testing an idea in physical form) can be something that implies aspects of a world. It's like making a prop for the future/adjacent world you are imagining. Such design fiction artifacts might include a product catalog from some future world (as we did for IKEA, and our own TBD Catalog), a receipt from some future restaurant, or a magazine that would imply some aspects of the future of travel, or leisure, or fashion. Some design fictions are quite expansive and thorough, some are little hints. But the point is to create an artifact/object and not be didactic about what it is. It just exists, unlike a story which will always be seen as a story. Neither is better — they are simply different ways of activating the imagination. One is written like a story, the other is constructed.

There's much more in The Manual of Design Fiction, due out in a few weeks.