Scoped Cordis registrations. createScope(ctx, key) returns a context whose registrations are visible only to the matching dispatch subject and are owned by one backing fiber. The agent loop creates one scope per live agent; lower-level packages depend only on the generic ScopeKey mechanism.

Public API

createScope(ctx, key): Scope creates a tagged child context. Derived contexts inherit the tag; a nested scope replaces it. Primitive keys and creation during disposal throw.
Scope.ctx is the registration context.
Scope.rawDispose is the exact Cordis disposer used when nesting the scope in a composite effect.
Scope.dispose(): Promise<void> is the idempotent quiescence boundary for ordinary callers, including races started through rawDispose.
scopeOf(ctx) returns the nearest key or undefined for global registration.
scopeTarget(base, key): Scoped<T> creates the event receiver that admits global listeners plus listeners for key. An undefined key admits only global listeners; Cordis { global: true } remains an explicit bypass.
Scoped<T> brands scope-filtered event receivers at compile time. isScopeCarrier() and carrierKeyOf() support runtime invariants.
scopeHost(ctx, services) provides a test/tooling host whose disposer awaits its fiber and all scopes it minted.

Visibility and cleanup come from the same registration context, so a contribution cannot be visible to one scope but owned by another. A scoped context retains the minting plugin's injected service view; mint it from a context whose capabilities are appropriate for holders.

See the agent-scope RFC for rationale and lifecycle integration.