OwnedStore

The rows of one model, narrowable to the user who owns them.

It sits beside Store rather than inside it because the five operations are the vocabulary the derived seven speak and a sixth would be a query language on the seam. Narrowing is a different question: it answers a Store[A] and hands it back, so everything downstream of a narrowing still sees exactly the five, and a derived handler cannot tell a scoped store from a whole one. That is the point. The refusal of a foreign row is then the absence of a row rather than a check somebody has to remember to write.

Both halves of Store implement it, db's through a where on the owner column and http's through a filter, and the generated route table is the only file where both names appear.