The app query client (src/queryClient.ts) sets no retry option, so React Query's default applies — 3 retries with exponential backoff for every error, including 4xx. Expected client errors then retry pointlessly: e.g. the courseware outline's expected 403 (denied/logged-out learner) retries 3× (~7s) before it finally settles, and any 4xx slow-fails behind the backoff.

Adopt a smart retry that fails fast on 4xx and only retries server/network errors — the same policy landed in openedx/frontend-app-learner-dashboard#801. Use the existing getResponseStatus helper (src/data/http-error.ts) for consistency with the onError logging.

export const createQueryClient = (store: Store) => new QueryClient({
  queryCache: createAppQueryCache(store),
  defaultOptions: {
    queries: {
      retry: (failureCount, error) => {
        const status = getResponseStatus(error);
        if (status !== undefined && status >= 400 && status < 500) { return false; }
        return failureCount < 3;
      },
    },
  },
});

Test: a 4xx query calls the fn once (no retry); a 5xx/network query retries up to 3×.

Part of #1946.