/**
 * FBX 5.x (and older) documents store everything at the top level: one `Model` node per object with inline
 * geometry, materials, skin links, lights and cameras, and `Children` lists instead of connections. This module
 * rewrites such a document into the 6.x layout (`Objects`, `Connections`, `Takes`) so the rest of the importer
 * can treat both the same way. The rules follow the FBX SDK's legacy reader as implemented by ufbx.
 */
import { type FBXDocument } from "../types/fbxTypes.js";
/** True for pre-6000 files: no `Objects` section but top-level `Model` nodes. */
export declare function isLegacyDocument(doc: FBXDocument): boolean;
/** Rewrites a legacy document into the 6.x object/connection layout. */
export declare function upgradeLegacyDocument(doc: FBXDocument): FBXDocument;