Function route_labels 

pub fn route_labels(
    indexed: &IndexedDocument<'_>,
    route: RouteId,
) -> Vec<(RouteLabelId, FracVal)>

A wire’s name labels as the geometry layer reads them: the entity to write back to, and the arc length along the solved polyline it sits at. Resolved through the route index in the document’s one draw order, so hit-testing, rendering, and re-anchoring all walk the same list.