import type { PostHog } from '../posthog-core';
/**
 * Records a duration histogram for every HTTP or HTTPS `fetch` and
 * `XMLHttpRequest` the page makes, except the SDK's own. Observation only: the
 * wrappers never change the request arguments or its settlement. Fetch returns
 * a derived promise so rejected requests remain observable to the caller and to
 * the browser's unhandled-rejection handling.
 *
 * Each transport is measured to the boundary its API exposes: a `fetch` promise
 * settles when the response headers arrive, and `loadend` fires after the whole
 * XHR response body. Aligning them would mean reading the fetch response body,
 * which an observer must not do.
 *
 * While `metrics.network` is off the wrappers pass every request straight
 * through. The returned function removes them; if another wrapper was layered
 * on top and ours cannot be spliced out, it stays in place as a pass-through.
 */
export declare const startNetworkMetrics: (instance: PostHog) => (() => void);