Struct ScriptPlan 

pub struct ScriptPlan {
    pub packer: Molpack,
    pub structures: Vec<StructurePlan>,
    pub output: PathBuf,
    pub nloop: usize,
    pub filetype: Option<String>,
}

Loader-agnostic lowering of a Script: paths resolved, restraints kept as parsed RestraintSpecs, no filesystem access yet.

Iterate structures, load each StructurePlan::filepath with whatever frame loader you have, build a Target from the frame, and call StructurePlan::apply to stamp on the script’s restraints / centering / fixed placement.

Fields

packer: Molpack

Packer pre-configured with tolerance, seed, and (optional) pbc.

structures: Vec<StructurePlan>

One entry per structure … end structure block, in source order.

output: PathBuf

Resolved output file path.

nloop: usize

Outer-loop iteration cap (nloop keyword; default 200 * ntype).

filetype: Option<String>

Global filetype override (script-level), if any. Frame loaders should fall back to extension-based detection when this is None.