/**
 * Toast the session page's read failures, once per error. The read hooks keep
 * transient failures (a rolling deploy, a network blip) quiet while they retry
 * and keep one stable error per outage, so an error reaches here only when it
 * is definitive or outlasted the quiet window. A 404 renders the unavailable
 * route instead of a toast.
 */
export declare function useSessionFailureToasts(loadError: Error | null, streamError: Error | null): void;