Ask HN: Guidelines for building custom document types

Say you want to store organized data in a single file. For the time being, assume it can be something like game saves for a custom game.

I have the following leanings:

- Binary assets might need to be included, but a separate asset server is possible

- The file should be easily made inspectable via tools equivalent to jq

- the file format can't paint me into a corner, in other words I should be able to make a V2, and it should be easy to convert to a V2.

- this probably is a trivial point, but the file should be readable from and writable to typed languages (scala and typescript).

There must be some "design patterns" informing how to go about building this sort of thing. IIRC, one of PlanGrid's founders used his experience working with file types at disney to help them build blueprint storage/display tools. So there must be some consistent way to explore this field (haven't seen much codified).