Function frame_kind_name 

pub fn frame_kind_name(kind: &FrameKind) -> &str

The snake_case wire name of a FrameKind, matching its serde representation and the strings a provider lists in Capabilities::query’s kinds.

A thin delegation to FrameKind::as_str, kept because several call sites read better as a function. It used to be a hand-written match returning &'static str; that duplicated the vocabulary in a second place and, worse, could not name a kind the host did not know. Now that the vocabulary is open the borrow is tied to the kind, because an unknown kind owns its string.