(John, there’s another type of field called an

AsyncField

, which indicates that we need the engine for hydration. You call

await Get[SourcesResult](Sources, my_tgt.get(Sources)

, rather than

my_tgt.get(Sources).value

. Only about 5-10% of fields are `AsyncField`s. They’re orthogonal to this discussion because `AsyncField`s are by definition always lazy.)