Function lower_dot_source 

pub fn lower_dot_source(
    source: &str,
    p: ZipPar,
) -> Result<(usize, String, String), String>

A LOGOS dot product, recognized (tensor_recognize::recognize_dot) and emitted as Spatial’s DotProduct regression app at the knobs p: (n, class name, Spatial source), or a typed reason (not a dot product; a tile that does not divide the length; a sum the app’s 32-bit Int would wrap).