/** Reversible opening changes when a Unit begins or stops inheriting its predecessor. */
import type { StudioVideoUnit, VideoUnitDependency } from "./studio-video-units.ts";
/**
 * Change only the opening relationship and preserve authored prose and image files.
 * @param unit Current persisted Unit.
 * @param dependency Validated adjacent predecessor, or null to unlink.
 * @returns Updated Unit; the project writer validates and saves it atomically.
 */
export declare function changeVideoUnitDependency(unit: StudioVideoUnit, dependency: VideoUnitDependency | null): StudioVideoUnit;
/** Normalize old linked openings on schema upgrade without deleting their authored assets. */
export declare function migrateVideoUnitDependencies(units: StudioVideoUnit[]): StudioVideoUnit[];