Browser-based IFC/BIM 3D viewer built on Three.js, web-ifc and @thatopen/fragments. Ships a vanilla TypeScript core plus an optional React subpath (`kui-viewer/react`) exposing the `<KUIViewer />` component, a `ViewerProvider`, and a Zustand-backed `useViewerStore` hook for selection, federation and spatial-tree state. In-viewport widgets — an interactive NavCube, a pill toolbar (`viewer.toolbar`) and a dolly ZoomSlider — mount as children of `<KUIViewer />` and wire themselves to the live camera via `useViewer`.