DynamicRegistry
The dynamic_dto names a database knows, and the class each one stands for.
It is kept in the driver's type catalog, attached under its own class, rather than on the client that registered it. A discriminator is stored in the data, so what it means is a property of the database: every client on it has to read land_grant as the same class, and a converter on the catalog - which every client on the database reaches - can only answer for names it can see. Kept in the catalog, the registry is also replaced whole with it, dropped by removeCatalog, and pinned for an execution along with the converters reading it.
Functions
The registration for an exact class, which is how a value being written finds its own.
The registration a stored discriminator names.
This registry with registration in it.