import type { Cell } from "../elements.js";
import type { Frame } from "../frame.js";
/**
 * Composite a Frame tree into a flat 2D grid of Cells.
 * Recursively blits children on top of parents.
 * Uses the frame's own x/y as the origin so sub-frames
 * returned by findByKey() render correctly.
 */
export declare function flatten(frame: Frame, width: number, height: number): Cell[][];