/**
 * Register the engine's built-in custom model loaders (currently the Gaussian
 * Splat loader, backed by Spark).
 *
 * Called from {@link initNeedleLoader} rather than run as a bare module
 * side-effect. A side-effect-only `import "./engine_loaders.custom.js"` gets
 * tree-shaken away when an app bundles the engine — this file is not listed in
 * the package's `sideEffects` — which silently disabled splat loading (a
 * dropped `.ply` fell back to the GLTFLoader). A called export cannot be
 * eliminated. Idempotent, so it is safe to call on every engine init.
 * @internal
 */
export declare function registerBuiltinCustomLoaders(): void;