/**
 * Fired on the {@link Engine} when an update request is received for a workflow.
 * Contains the `updateId`, `name`, and `payload`. Precedes a corresponding
 * {@link UpdateCompletedEvent} once the workflow handler processes the update.
 *
 * @example
 * ```ts
 * import { Engine, UpdateReceivedEvent } from '@lostgradient/weft';
 *
 * const engine = new Engine();
 * engine.addEventListener(UpdateReceivedEvent.type, (event) => {
 *   console.log('update', event.name, 'received for', event.workflowId, '(id:', event.updateId, ')');
 * });
 * ```
 */
export declare class UpdateReceivedEvent extends Event {
    static readonly type: "update:received";
    readonly updateId: string;
    readonly workflowId: string;
    readonly name: string;
    readonly payload: unknown;
    constructor(updateId: string, workflowId: string, name: string, payload: unknown);
}
/**
 * Fired on the {@link Engine} when a workflow update handler returns a result
 * (or throws an error). Check `e.error` to distinguish success from failure;
 * on success, `e.result` holds the handler's return value.
 *
 * @example
 * ```ts
 * import { Engine, UpdateCompletedEvent } from '@lostgradient/weft';
 *
 * const engine = new Engine();
 * engine.addEventListener(UpdateCompletedEvent.type, (event) => {
 *   if (event.error) {
 *     console.error('update', event.name, 'failed:', event.error);
 *   } else {
 *     console.log('update', event.name, 'result:', event.result);
 *   }
 * });
 * ```
 */
export declare class UpdateCompletedEvent extends Event {
    static readonly type: "update:completed";
    readonly updateId: string;
    readonly workflowId: string;
    readonly name: string;
    readonly result: unknown;
    readonly error: string | undefined;
    constructor(updateId: string, workflowId: string, name: string, result: unknown, error?: string);
}