CanGet

Capability: an A can be read out of an S — the carrier-free surface of any optic whose carrier admits accessor.Accessor (Lens, Iso, Getter).

This is the type to name in a consuming signature: leave the subject generic and demand only the evidence the method needs — def render[T](t: T)(using id: CanGet[T, OrderId]). Concrete optic types belong where optics are constructed and composed. One optic given per (S, A) pair should be in scope at a call site — capabilities follow ordinary typeclass coherence; newtype same-typed foci apart rather than relying on implicit priority to pick between them.