Build a resource tag from an existing service interface as the single source of truth. The type parameter I is the interface; the contract gives a schema only for the members you want on the wire — every other interface member becomes a local (surfaced via InjectLocal, carrying Local<I>). One merged handle, identical whether you hold the local layer or a client; the only difference is that a client can't call the locals (a compile error — unsatisfied Local).

Locals are written bare — Hyperlink.local, no () — and take their type from I. A bare local with no matching interface member is rejected at the call (see Validate).

Two type parameters, like Tag: Self (the class — the tag's nominal identity, Local brand) and I (the service interface — a standalone type; passing the class itself as I would be a circular base reference).

interface CounterShape {
  readonly current: Effect.Effect<number>;            // local (no schema)
  readonly add: (by: number) => Effect.Effect<number>; // wired
}
class Counter extends Hyperlink.fromService<Counter, CounterShape>()("counter", {
  current: Hyperlink.local,
  add: Hyperlink.effectFn(Schema.Number, Schema.Number),
}) {}