/**
* Deliverability and compliance helpers. Currently ships primitives for
* RFC 2369 / RFC 8058 List-Unsubscribe: signing one-click tokens and a
* framework-agnostic HTTP handler that verifies + dispatches to a
* suppression store.
*
* @module
*/
import type { SuppressionStore } from "../suppression/index.mjs";
/** Opaque, tamper-proof token encoding the unsubscribe subject. */
export interface UnsubscribeTokenPayload {
	recipient: string;
	campaign?: string;
	/** Expiry as epoch seconds. Omit for non-expiring tokens. */
	exp?: number;
}
/** Sign a one-click unsubscribe token with HMAC-SHA256. */
export declare function signUnsubscribeToken(payload: UnsubscribeTokenPayload, secret: string): Promise<string>;
/** Verify a token. Returns the payload on success, `null` on tamper /
*  expiry. Constant-time via Web Crypto `verify`. */
export declare function verifyUnsubscribeToken(token: string, secret: string, now?: () => number): Promise<UnsubscribeTokenPayload | null>;
/** Options for `defineUnsubscribeHandler`. */
export interface UnsubscribeHandlerOptions {
	secret: string;
	/** Query-string key that carries the token. Default: `t`. */
	tokenParam?: string;
	/** Suppression store receiving the opt-out. */
	store?: SuppressionStore;
	/** Optional hook fired after a successful unsubscribe. */
	onUnsubscribe?: (payload: UnsubscribeTokenPayload) => void | Promise<void>;
	/** Custom clock for testing. */
	now?: () => number;
}
/** Framework-agnostic handler — give it a `Request`, it returns a
*  `Response`. RFC 8058 requires 200 OK on POST with no user
*  confirmation; we honor that. GET also works for mail-client URL
*  rendering. */
export declare function defineUnsubscribeHandler(opts: UnsubscribeHandlerOptions): (request: Request) => Promise<Response>;