/**
 * Patches window.fetch at module-import time — before any React component
 * mounts and before any AI SDK can capture the fetch reference. This is the
 * key difference from installing the patch in a useEffect: by the time a
 * useEffect runs, the Vercel AI SDK (and others) may have already resolved
 * their fetch reference and bypass the patch entirely.
 *
 * Handles three credit-error surfaces:
 *   1. HTTP 402 with { code: "insufficient_credits" } — regular JSON routes.
 *   2. HTTP 200 streaming body containing "insufficient_credits" — SSE, ndjson,
 *      or Vercel AI SDK data-stream (text/plain) routes.
 *   3. Manual call to notifyInsufficientCredits() from any error handler.
 */
type Listener = () => void;
/**
 * Subscribe to insufficient-credits events detected in window.fetch.
 * Returns an unsubscribe function for use in useEffect cleanup.
 *
 * The fetch patch is installed at module load time regardless of whether
 * anyone calls this function. This exists for components that need a direct
 * callback rather than the global DOM event.
 */
export declare function subscribeFetchWatcher(listener: Listener): () => void;
export {};