service-port-shape-only

Intent: a port is a shape-only Context.Service (v3: Context.Tag), with no implementation attached.

// ❌ no
class Agent extends Context.Service<Agent, Shape>()("app/Agent", { make: makeAgent }) {}

// ✅ yes
export class Agent extends Context.Service<
    Agent,
    { readonly search: (name: string) => Effect.Effect<RaceCard, AgentError> }
>()("app/agent/Agent") {}

Trigger: the second argument of Context.Service<…>()(id, opts); a static layer, static Default or static Live member on a Context.Service or v3 Context.Tag(id)<…>() class; any Effect.Service.

Exemptions and blind spots: a Context.Service or v3 Context.GenericTag assigned to a variable is not seen: see service-not-as-class (effecttsgo). Statics with other names slip through.

Why: make and a static layer tie the port to a default implementation, while the port must stay a contract any adapter can satisfy. It is a convention, not Effect’s idiom: Effect’s own docs put static readonly layer on the service.

Options: none

Fix: none