Function format_reference_drag_curve 

pub fn format_reference_drag_curve(
    drag_model: &DragModel,
    format: ReferenceDragCurveFormat,
) -> String

Render one built-in reference drag curve as text, identically on every surface (MBA-1424 / MBA-1426).

This is THE formatter — the native CLI’s drag-curve and the browser terminal’s both call it, so their table, CSV and JSON output cannot drift apart. That is a lesson, not a flourish: the recoil CSV header diverged between the two surfaces (velocity_m/s vs velocity_mps, MBA-1418) precisely because each carried its own copy of the format strings, and the divergence survived because the imperial spelling happened to agree.

Returned strings are newline-terminated; callers print or splice them verbatim. PDF is not a form of this data — each surface rejects it with its own error convention before calling in.