fix(scope): close remaining ownership boundaries

packages/core/scope/README.md

@@ -12,7 +12,7 @@ Scoped-context registration primitive. `createScope(ctx, key)` mints a Cordis co
 - `scopeTarget(base: T, key?: ScopeKey): Scoped<T>` Build the dispatch `thisArg` for a scope-filtered event: composes `base`'s own `Context.filter` with the scope predicate (untagged listener ⇒ admitted; tagged ⇒ admitted iff tag === key; `key === undefined` ⇒ untagged only). Listener `this` stays `base`-shaped. `{ global: true }` listeners bypass filtering (Cordis semantics).
 - `Scoped<T>` The compile-time carrier brand: scope-filtered events demand it as their `this` type, so dispatching with a bare subject is a compile error.
 - `isScopeCarrier(value)` / `carrierKeyOf(value)` Runtime carrier marks, used by the dev invariants to assert every scope-filtered dispatch carries a carrier keyed to the subject its arguments name.
-- `scopeHost(ctx, services)` Test/tooling host whose shared `dispose()` waits for both the host fiber and every minted scope, including a child already tearing down through `rawDispose`.
+- `scopeHost(ctx, services)` Test/tooling host that snapshots the requested service list before activation, fails loud with stable missing-service diagnostics, and whose shared `dispose()` waits for both the host fiber and every minted scope, including a child already tearing down through `rawDispose`.
 
 ## Design contract