/**
 * Vary Params Decoding
 *
 * This module is shared between server and client.
 */
export type VaryParams = Set<string>;
type FulfilledVaryParamsThenable = {
    status: 'fulfilled';
    value: VaryParams;
} & PromiseLike<VaryParams>;
type PendingVaryParamsThenable = {
    status: 'pending' | 'resolved_model';
    value: unknown;
} & PromiseLike<VaryParams>;
export type VaryParamsThenable = FulfilledVaryParamsThenable | PendingVaryParamsThenable;
/**
 * Synchronously reads vary params from a thenable.
 *
 * By the time this is called (client-side or in collectSegmentData), the
 * thenable should already be fulfilled because the Flight stream has been
 * fully received. We check the status synchronously to avoid unnecessary
 * microtasks.
 *
 * Returns null if the thenable is still pending (which shouldn't happen in
 * normal operation - it indicates the server failed to track vary params).
 */
export declare function readVaryParams(thenable: VaryParamsThenable): VaryParams | null;
export {};