import { type Effect, Ref } from "effect";
/**
 * Entity constraint: must have a readonly string `id` field.
 */
type HasId = {
    readonly id: string;
};
/**
 * Creates a Ref holding a ReadonlyMap<string, T> from an initial array of entities.
 *
 * Each entity is keyed by its `id` field, giving O(1) lookup by ID.
 * If no initial data is provided, the Ref starts with an empty map.
 *
 * @param initialData - Array of entities to seed the collection state
 * @returns Effect producing a Ref containing a ReadonlyMap keyed by entity ID
 */
export declare const createCollectionState: <T extends HasId>(initialData?: ReadonlyArray<T>) => Effect.Effect<Ref.Ref<ReadonlyMap<string, T>>>;
export {};
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