/**
 * Lightweight transcript collector used by `verifyEmail` to capture a
 * structured trace of every subsystem call (syntax / disposable / free /
 * MX / SMTP / WHOIS / name detection / domain suggestion).
 *
 * Two collectors:
 *   - `ArrayTranscriptCollector` — accumulates steps, exposed in result.
 *   - `NULL_COLLECTOR` — no-op singleton used when capture is disabled, so
 *     the call sites in `verifyEmail` never need an `if (transcript)` branch.
 */
import type { VerificationStep, VerificationStepKind } from './types';
export interface TranscriptCollector {
    /** Run `fn`, time it, push a step record. Re-throws on error after recording. */
    record<T>(kind: VerificationStepKind, fn: () => Promise<T> | T, detailsFor: (value: T) => Record<string, unknown>): Promise<T>;
    /** Push a pre-built step. Useful when timing is owned by the callee. */
    push(step: VerificationStep): void;
}
export declare class ArrayTranscriptCollector implements TranscriptCollector {
    readonly steps: VerificationStep[];
    record<T>(kind: VerificationStepKind, fn: () => Promise<T> | T, detailsFor: (value: T) => Record<string, unknown>): Promise<T>;
    push(step: VerificationStep): void;
}
/** No-op collector — every method is a no-op. Used when capture is disabled. */
export declare const NULL_COLLECTOR: TranscriptCollector;