import { type ArkmeAvatarImagePayload, type ArkmeAvatarPersistentCache } from './avatar-image-store.js';
/** Validate browser-persisted bytes too: base64 syntax is not image validity. */
export declare function decodableAvatar(payload: ArkmeAvatarImagePayload): Promise<boolean>;
/** Browser bytes survive reloads. Host remains the authenticated source on misses.
 * No TTL for immutable refs; quota eviction and clearing site data are cache misses.
 * Synthetic keys are never fetched and include the environment/account scope.
 */
export declare class BrowserAvatarPersistentCache implements ArkmeAvatarPersistentCache {
    private readonly decode;
    constructor(decode?: (payload: ArkmeAvatarImagePayload) => Promise<boolean>);
    private writes;
    private key;
    read(scope: string, ref: string): Promise<ArkmeAvatarImagePayload | undefined>;
    write(scope: string, ref: string, payload: ArkmeAvatarImagePayload): Promise<void>;
}
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