/**
 * Represents the unique identifier for a durable entity instance.
 *
 * An entity ID is composed of two parts:
 * - **name**: The entity type name (normalized to lowercase)
 * - **key**: The entity instance key (case-preserved)
 *
 * The string representation follows the format: `@{name}@{key}`
 *
 * @example
 * ```typescript
 * // Create a new entity ID
 * const entityId = new EntityInstanceId("Counter", "user-123");
 * console.log(entityId.name); // "counter" (lowercased)
 * console.log(entityId.key);  // "user-123" (preserved)
 * console.log(entityId.toString()); // "@counter@user-123"
 *
 * // Parse from string
 * const parsed = EntityInstanceId.fromString("@counter@user-123");
 * ```
 */
export declare class EntityInstanceId {
    /**
     * The entity type name. Entity names are normalized to lowercase.
     */
    readonly name: string;
    /**
     * The entity instance key. Keys are case-preserved.
     */
    readonly key: string;
    /**
     * Creates a new EntityInstanceId.
     *
     * @param name - The entity type name. Will be normalized to lowercase.
     *               Must not be empty and must not contain '@' characters.
     * @param key - The entity instance key. Must not be null or undefined.
     * @throws {Error} If name is empty or contains '@' characters.
     * @throws {Error} If key is null or undefined.
     */
    constructor(name: string, key: string);
    /**
     * Constructs an EntityInstanceId from its string representation.
     *
     * @param instanceId - The string representation of the entity ID in the format `@{name}@{key}`.
     * @returns The parsed EntityInstanceId.
     * @throws {Error} If the instanceId is empty or not in valid format.
     *
     * @example
     * ```typescript
     * const entityId = EntityInstanceId.fromString("@counter@user-123");
     * console.log(entityId.name); // "counter"
     * console.log(entityId.key);  // "user-123"
     * ```
     */
    static fromString(instanceId: string): EntityInstanceId;
    /**
     * Returns the string representation of this entity ID.
     *
     * @returns The entity ID in the format `@{name}@{key}`.
     */
    toString(): string;
    /**
     * Returns the JSON representation of this entity ID.
     * This is called automatically by JSON.stringify() to produce a compact string representation.
     *
     * @returns The entity ID as a string in the format `@{name}@{key}`.
     */
    toJSON(): string;
    /**
     * Checks equality with another EntityInstanceId.
     *
     * @param other - The other EntityInstanceId to compare with.
     * @returns True if both name and key match, false otherwise.
     */
    equals(other: EntityInstanceId | null | undefined): boolean;
}