Function export_step_report_named 

pub fn export_step_report_named(
    solids: &[(String, &BrepSolid)],
    name: &str,
    unit: &str,
    timestamp: &str,
    pmi: Option<&StepPmi<'_>>,
) -> Result<StepExportReport, String>

The full single-product writer: each body carries its SCENE NAME (MANIFOLD_SOLID_BREP name — and the key the PMI references resolve through), and an optional PMI block is written as AP242 semantic representation + polyline presentation + saved views ([pmi]).

This is the FLAT lane: one PRODUCT, every body in it, no assembly structure. A document with components goes through assembly::export_step_assembly_report instead.