/**
 * Middleware wrapper that enforces HMAC signature verification on a proxy handler.
 *
 * Usage:
 * ```ts
 * export default withSigning(defineEventHandler(async (event) => {
 *   // ... handler logic
 * }))
 * ```
 *
 * Behavior:
 * - Reads `runtimeConfig.nuxt-scripts.proxySecret` (server-only).
 * - If no secret is configured: passes through (signing not yet enabled).
 *   This allows shipping handler wiring before components emit signed URLs.
 *   Once `NUXT_SCRIPTS_PROXY_SECRET` is set, verification is enforced.
 * - If a secret IS configured and the request's signature is invalid: 403.
 * - Otherwise, delegates to the wrapped handler.
 *
 * The outer wrapper runs before any handler logic, so unauthorized requests
 * never reach the upstream fetch and cannot consume API quota.
 */
import type { EventHandler, EventHandlerRequest, EventHandlerResponse } from 'h3';
export declare function withSigning<Req extends EventHandlerRequest = EventHandlerRequest, Res extends EventHandlerResponse = EventHandlerResponse>(handler: EventHandler<Req, Res>): EventHandler<Req, any>;