Function diagnostics_scene 

pub fn diagnostics_scene(draft: &Draft) -> Expr

Presents a Draft’s diagnostics as a deterministic scene/overlay.

A committable draft (no diagnostics) yields an affirmative overlay carrying an ok status and a single confirmation line. A rejected draft yields one scene/badge per diagnostic, in order, each tagged with a severity token and carrying its message; a diagnostic that has a machine-readable code is anchored to it through a code field. The overlay’s status is rejected when any diagnostic is present.