Function root_menu_spec 

pub fn root_menu_spec(
    source: &str,
    ids: &MagitActionIds,
    ctx: &TransientContext,
    gates: &DispatchGates,
) -> Option<TransientSpec>

Build one root menu by name — the SAME spec the dispatch nests, so a chord and the menu path to it can never disagree.

None for an unknown name; the caller then leaves the transient unopened rather than showing an empty menu.