Function add_to_path 

pub fn add_to_path(
    world_path: &str,
    name: Option<&str>,
    target: &str,
    template: Option<&str>,
) -> Result<()>

Add an asset to world_path and rebuild. See module docs.

template selects a named scaffold preset when scaffolding fires (target is .glb, world has no renderer trigger). None uses the default scaffold; Some("minimal-3d-world") layers that template’s entries. Unknown names error out before touching the world file.