/**
 * The lifecycle events Cache Components validation emits so E2E tests can
 * locate the validation window in the CLI output. Each is serialized between
 * `<VALIDATION_MESSAGE>` delimiters (see `formatValidationEvent`) and parsed
 * back by the test harness. Produced by the in-process validation in
 * `app-render.tsx` (both dev and build) and by the validation worker, which is
 * why the shape lives here rather than in a single producer.
 *
 * `requestId` correlates a start with its matching end/aborted. Dev and worker
 * validation use the render's request id; build validation, which has no such
 * id, uses a stringified timestamp instead.
 */
export type ValidationEvent = ValidationStartEvent | ValidationEndEvent | ValidationAbortedEvent;
export type ValidationStartEvent = {
    type: 'validation_start';
    requestId: string;
    url: string;
    /**
     * Only reported for development validation.
     */
    responseFinished?: boolean;
};
export type ValidationEndEvent = {
    type: 'validation_end';
    requestId: string;
    url: string;
};
/**
 * Emitted when detached validation is aborted. It can appear without a start
 * when cancellation happens before validation runs, or after a start instead of
 * an end when in-flight validation is cancelled.
 */
export type ValidationAbortedEvent = {
    type: 'validation_aborted';
    requestId: string;
    url: string;
};
/**
 * Wraps a validation event in the `<VALIDATION_MESSAGE>` delimiters the test
 * harness scans for. The caller chooses the output stream (dev validation logs
 * to stdout; build validation uses stderr for deterministic ordering).
 */
export declare function formatValidationEvent(event: ValidationEvent): string;