The definition of a Schema itself is typed of course (https://tinybase.org/api/store/type-aliases/schema/schema/) but I haven't thought of a way to then magically create developer-time definitions of a Schema on a Store. There is also a way to 'programmatically' enforce a Schema (https://tinybase.org/guides/schemas-and-persistence/mutating...) so you could (in theory) implement all sorts of wild and wonderful constraints.

I think for now you'll need to create your own local type definition that models the data you know is in the Store. But let me think a bit more about this.