import { Context, Crypto, LDLogger, Storage } from '@launchdarkly/js-sdk-common';
/**
 * Suffix appended to context storage keys to form the freshness storage key.
 */
export declare const FRESHNESS_SUFFIX = "_freshness";
/**
 * Persisted freshness record stored at `{contextStorageKey}_freshness`.
 */
export interface FreshnessRecord {
    /** Timestamp in ms since epoch when data was last received. */
    timestamp: number;
    /** SHA-256 hash of the full context's canonical JSON. */
    contextHash: string;
}
/**
 * Computes a SHA-256 hash of the context's full canonical JSON.
 * Returns `undefined` if the context cannot be serialized.
 */
export declare function hashContext(crypto: Crypto, context: Context): Promise<string | undefined>;
/**
 * Reads the freshness timestamp from storage for the given context.
 *
 * Returns `undefined` if no freshness record exists, the data is corrupt,
 * or the context attributes have changed since the freshness was recorded.
 */
export declare function readFreshness(storage: Storage, crypto: Crypto, environmentNamespace: string, context: Context, logger?: LDLogger): Promise<number | undefined>;
//# sourceMappingURL=freshness.d.ts.map