/**
 * Encodes an action failure for the redirect cookie. When the payload fits
 * inside the cookie limit, it is embedded directly as a signed base64url JSON
 * value. When it is too large, it is stored in memory and only a short signed
 * id is written to the cookie.
 *
 * The cookie is signed with HMAC-SHA256 to prevent forgery (A-20).
 *
 * @returns The cookie value to set on the redirect response.
 */
export declare function encodeActionErrorCookie(data: unknown, status: number): {
    value: string;
    storeId?: string;
};
/**
 * Decodes a cookie value (previously produced by `encodeActionErrorCookie`)
 * into the failure payload. Verifies the HMAC signature first, then resolves
 * in-memory overflow entries and deletes them after reading.
 */
export declare function decodeActionErrorCookie(value: string | undefined | null): {
    data: unknown;
    status: number;
} | undefined;
/** Name of the cookie used to relay action errors. */
export declare const ACTION_ERROR_COOKIE = "__nix_js_action_error";
/** Builds the Set-Cookie header value that clears the error cookie. */
export declare function clearActionErrorCookieHeader(): string;
/** Builds the Set-Cookie header value that sets the error cookie. */
export declare function setActionErrorCookieHeader(value: string): string;