/**
 * In-app scroll buffer.
 *
 * Covers cavekit-fullscreen-viewport R5 (buffer semantics), R6 (scroll controls).
 * The buffer owns the session transcript; the TUI renders whatever slice the
 * buffer exposes for the current viewport.
 */
export type ScrollMode = "tail" | "paused";
export interface ScrollBufferOptions {
    maxLines?: number;
    wrap?: boolean;
}
/**
 * Session transcript with viewport and follow-tail semantics.
 *
 * The buffer stores raw "logical" lines as appended. For rendering, lines are
 * soft-wrapped to the current viewport width producing "display" lines. The
 * viewport is defined in display lines, so the scroll math operates on the
 * post-wrap stream and stays consistent after resize.
 */
export declare class ScrollBuffer {
    private logical;
    private wrapEnabled;
    private readonly maxLines;
    private wrappedCache;
    private cachedWidth;
    private viewportWidth;
    private viewportHeight;
    /** Offset from the top of the wrapped stream (display-line index of viewport top). */
    private topOffset;
    private _mode;
    private _unseen;
    constructor(opts?: ScrollBufferOptions);
    append(lines: string[]): void;
    /**
     * Replace the last `count` logical lines with `lines`. Used for streaming
     * updates to a single message that grows in-place. Tail/paused behavior
     * mirrors append().
     */
    replaceTail(count: number, lines: string[]): void;
    replaceAll(lines: string[]): void;
    clear(): void;
    setViewportHeight(rows: number): void;
    setViewportWidth(cols: number): void;
    get totalLines(): number;
    get viewHeight(): number;
    get viewWidth(): number;
    scrollBy(delta: number): void;
    pageUp(): void;
    pageDown(): void;
    halfPageUp(): void;
    halfPageDown(): void;
    jumpToTop(): void;
    jumpToTail(): void;
    get isAtTail(): boolean;
    get mode(): ScrollMode;
    unseenCount(): number;
    /** Returns exactly viewportHeight display lines (pads with "" when short). */
    render(): string[];
    private setMode;
    private snapToTail;
    private clampTopOffset;
    private trimToMax;
    private invalidateCache;
    private getWrapped;
    private countDisplayLines;
}
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