import type { Bridge } from "./types.js";
/** Options for {@link startAutoResize}. */
export interface AutoResizeOptions {
    /**
     * Minimum change (in px) on either axis before a new size is reported. Guards
     * against sub-pixel churn and `ResizeObserver` feedback loops. Default `1`.
     */
    threshold?: number;
}
/**
 * Observe the document's content box and emit {@link RESIZE_MESSAGE} to the host
 * whenever it changes, so the host can size a `fit`/auto container to the content.
 *
 * The content's *intrinsic* size is measured from the document body's
 * `scrollWidth/scrollHeight` — NOT `documentElement`, whose scroll size is floored
 * at the iframe viewport height. Measuring the root would create an
 * observe→resize→observe feedback loop: once the host sizes the iframe to a
 * placeholder taller than the content, `documentElement.scrollHeight` returns the
 * viewport height, the SDK reports that back, and the frame stays pinned at the
 * placeholder instead of shrinking to the content. The body's scroll box reflects
 * the intrinsic content and is independent of the iframe size. Reports are
 * coalesced to an animation frame and only sent when the value moves past
 * `threshold`.
 *
 * Safe to call in any environment: if there is no DOM or `ResizeObserver`, it is a
 * no-op and returns a no-op teardown.
 *
 * @returns a teardown that disconnects the observer and removes listeners.
 */
export declare function startAutoResize(bridge: Pick<Bridge, "send" | "on">, win: Window & typeof globalThis, options?: AutoResizeOptions): () => void;
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