isLegacyRef static method
Backward compatibility: check if ref looks like old format
Implementation
static bool isLegacyRef(String ref) {
// Old format: btn_0, tf_1, sw_2, etc.
// NOTE: elem_NNN is NOT a legacy ref — it's a numeric element ID from
// get_interactable_elements and must NOT be handled by legacy parsing.
if (ref.startsWith('elem_')) return false;
return RegExp(r'^[a-z]+_\d+$').hasMatch(ref);
}