/** Payment-required response returned to MCP when Valhalla returns 402. */
export interface L402PaymentRequired {
    status: 'payment_required';
    message: string;
    invoice: string;
    macaroon: string;
    payment_hash: string;
    payment_url: string;
    amount_sats: number;
}
/** In-memory L402 credential storage for a single MCP session. */
export declare class L402State {
    private macaroon;
    private preimage;
    /** Store credentials after the user pays an invoice. */
    store(macaroon: string, preimage: string): void;
    /** Return the Authorization header value, or null if no credentials. */
    getAuthHeader(): string | null;
    /** Clear stored credentials. */
    clear(): void;
}