Propose/implement a schema evolution process

[cjavad]

We need a process to accept schema changes, WIP.

[coffandro]

We really need this, currently I've found the following improvements we could make which I will hold off on until we have a process in place:

1. Size diameter shouldn't, imo, be allowed to be 0, most likely it'll be 1.75 so currently we're translating 0->0.75
2. The purchase links URLs should never be allowed to be an invalid URI, so no empty strings like what's valid rn.

[edvardm]

We need a process to accept schema changes, WIP.

Just out of curiosity, would you like to elaborate a bit? Not sure if I get the idea, but here's my take: json/yaml schemas are great, and you already have those. Simple way to go forward could be to add versioning to schemas (assume all current ones = v1). Set additionalProperties: false, but adding new, optional fields to schema is allowed within the same version. Breaking changes (new required fields, removals, type changes etc) require a new version.

Some could consider validation not being time-invariant a downside though, but other known options (use major/minor or some second property like list of extensions) seem like an overkill

[cjavad]

I think the technical adaptation (versioning, schema evolution) in itself is not a big issue, rather the process of agreeing on and furthering the design of the schema. The organizational part basically.