Function project_sheet_with 

pub fn project_sheet_with(
    model: &Model<'_>,
    sheet: &Sheet,
    views: &[PmiView],
    report: Option<&PmiReport>,
    context: &FrameContext,
    mode: &mut LinesMode<'_>,
) -> SheetDrawing

project_sheet, with what an exact-lines miss does chosen by mode: the engine’s viewport hands the pass to the runner and draws the mesh approximation until the answer lands; an export computes it here.