import { Options } from '../internal/resolveValue.ts';
import { Observer } from '../Observer/Observer.ts';
/**
 * Session-storage-backed state management.
 * Data persists only for the duration of the page session (until the tab is closed).
 */
export declare class SessionState extends Observer {
    static get<T = unknown>(key: string, options: Options<T> & {
        strict: true;
    }): T;
    static get<T = unknown>(key: string, options: Options<T> & {
        fallback: T;
    }): T;
    static get<T = unknown>(key: string, options?: Options<T>): T | undefined;
    /**
     * Stores a value in session storage.
     * Always JSON-serialises (see LocalState.set for the rationale).
     */
    static set<T = unknown>(key: string, value: T): void;
    static remove(key: string): void;
    static clear(): void;
    static has(key: string): boolean;
}