import type { FeedBlock } from "./feed-blocks.js";
export interface TranscriptWindowRow {
    readonly key: string;
    readonly line: string;
    readonly block: FeedBlock;
    readonly lineIndex: number | undefined;
}
export interface TranscriptWindow {
    readonly rows: readonly TranscriptWindowRow[];
    /** Rows the window occupies; always `<= budget`. */
    readonly height: number;
    /** Rows the flattened transcript would take without any budget. */
    readonly totalRows: number;
    /** Furthest the viewport may pull away from the bottom. */
    readonly maxOffset: number;
    /** Rows hidden below the viewport; `0` means pinned to the newest line. */
    readonly offset: number;
    readonly scrollAbove: number;
    readonly scrollBelow: number;
    readonly viewportRows: number;
    readonly firstItemId: string | undefined;
    readonly lastItemId: string | undefined;
    readonly visibleItemIds: ReadonlySet<string>;
}
export declare function flattenBlocks(blocks: readonly FeedBlock[]): readonly TranscriptWindowRow[];
export declare function totalTranscriptRows(blocks: readonly FeedBlock[]): number;
/**
 * One page: intro card is `blocks[0]` and scrolls together with the chat.
 * `offsetFromBottom = 0` pins the viewport to the newest row so streaming
 * content paints stick to the bottom; growth while scrolled away is anchored
 * by the wiring, which bumps the offset by the appended row count.
 */
export declare function planTranscriptWindow(flat: readonly TranscriptWindowRow[], budget: number, offsetFromBottom: number): TranscriptWindow;