import type { Cause } from "./catalog.js";
/** The time of an event: now, unless the payload says when. */
export declare const timestamp: import("./schema.js").Schema<string>;
/**
 * The payload of an event that happened at a time and for a reason: ActivationStarted, DoorbellPress. Both are
 * required by Alexa. The cause is the usual one of the event unless the payload names another.
 */
export declare const happened: (usually: Cause) => import("./schema.js").Schema<import("./schema.js").InferShape<{
    cause: import("./schema.js").Schema<{
        type: "APP_INTERACTION" | "PERIODIC_POLL" | "PHYSICAL_INTERACTION" | "RULE_TRIGGER" | "VOICE_INTERACTION";
    }>;
    timestamp: import("./schema.js").Schema<string>;
}>>;