import type { ReactiveController, ReactiveControllerHost } from 'lit';
/**
 * Options for AutoScrollController.
 */
export interface AutoScrollControllerOptions {
    /** Pixel threshold from bottom to consider "at bottom". Default 50. */
    threshold?: number;
    /** Called when scroll state transitions between at-bottom and away-from-bottom. */
    onScrollStateChange?: (isAtBottom: boolean) => void;
}
/**
 * AutoScrollController — automatically scrolls a container to the bottom
 * when observed elements resize (streaming text, images loading), unless
 * the user has scrolled up.
 *
 * Uses ResizeObserver on **individual elements** (set via `observeElements()`)
 * to detect content growth. The host component is responsible for calling
 * `scrollToBottom()` when new child elements appear (e.g. on `slotchange`).
 *
 * Used in: loquix-message-list
 */
export declare class AutoScrollController implements ReactiveController {
    private host;
    private _scrollContainer;
    private _isUserScrolled;
    private _isProgrammaticScroll;
    private _resizeObserver;
    private _observedElements;
    private _rafId;
    private _scrollGuardTimer;
    private _options;
    constructor(host: ReactiveControllerHost & HTMLElement, options?: AutoScrollControllerOptions);
    private get _threshold();
    hostConnected(): void;
    hostDisconnected(): void;
    /**
     * Attach to a scrollable container element.
     * Call this in updated() or after shadow DOM is ready.
     */
    attach(container: HTMLElement): void;
    detach(): void;
    /** Check if the user is near the bottom */
    get isAtBottom(): boolean;
    /** Whether the user has scrolled away from bottom */
    get isUserScrolled(): boolean;
    /**
     * Observe elements for size changes (e.g. slotted message items).
     * When an observed element resizes (streaming text, images loading),
     * auto-scroll is triggered if the user hasn't scrolled away.
     *
     * Call this whenever the set of slotted elements changes (slotchange).
     */
    observeElements(elements: Element[]): void;
    /** Programmatically scroll to bottom */
    scrollToBottom(behavior?: ScrollBehavior): void;
    /**
     * Scroll a specific element into view (centered in the scroll container).
     * Uses getBoundingClientRect + scrollTo to avoid cross-shadow-DOM scrolling issues.
     */
    scrollToElement(element: HTMLElement, behavior?: ScrollBehavior): void;
    private _scrollToBottomInternal;
    /**
     * Set a guard flag that suppresses user-scroll detection during programmatic scrolls.
     * `instant` completes immediately; `smooth` animates over ~300ms.
     */
    private _setProgrammaticGuard;
    private _onScroll;
}
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