Introduce capabilities that upload/* and store/* APIs could use to decide whether to proceed or fail

[Gozala]

Right now upload/* uses space/info capability to decide whether to allow mutations on store/* and upload/*

https://github.com/web3-storage/w3protocol/blob/f0b1e737f4d2f1689c5da04ad5408b114928d2fe/packages/access-api/src/service/index.js#L77-L89

I think it was a workaround which we need to fix, so that those APIs would not fail when space is registered through new provider/add capability.

My suggestion would be to expose two different capabilities

1. space/store/allocate that could succeed or fail depending if space has enough storage provided by storage provider.
2. space/upload/use - That succeeds if space has active upload/* capability provider or fail if it has no such provider.

[Gozala]

From @gobengo

What if you could we called the can= space/info/hasStorageProvider
2:56
more generally, a cap like space/info may provide a set of properties, but space/info/{property} would be granular to the specific property/attribute
2:56
(iirc ucans can have arbitrary number of /)
2:57
I think it is nice pattern to follow because it's inherently pretty easy to delegate (one-by-one) to any combination of properties that subset space/info (and therefore to avoid delegating permission to access properties other than those the issuer explicitly delegated) (edited)