@dinosaur Thanks for digging those up.

I wouldn't focus on things like absolute specifications and types at first. I'd rather try to find a minimal model to describe relationships between message types and their interpretation by clients. Once these relationships can be expressed, one could add some more metadata, like types, links, documentation, git-ssb repositories, and so on. This can develop organically - basically you build a client which uses some type of metadata and then encourage everyone to add this specific sort of metadata.

As for type schemata, I'd be interested in exploring the possibilities there. I spent a lot of time in the past year or so thinking about programming languages, which included exploring a bunch of type systems. But I believe finding a minimal vocabulary for self-description of message usage needs to be the first step. Any specific usage of this vocabulary should not determine the details of the design.

I think I'll spend the coming weekend exploring the meta-description rabbit hole and to write a summary - both of designs, and of use-cases. Then, I'll start writing a patchbay plugin to actually get something working.