Function describe_local_at 

pub fn describe_local_at(
    locals: &[LocalBinding],
    text: &str,
    offset: usize,
) -> Option<String>

v0.122 (editor-currency slice 1): a hover summary for the local binding / parameter under the cursor — let x: <ty> / param n: <ty>, rendered from the checker’s captured LocalBinding (its ty is already the surface type_ref form, matching inlay hints and signature help). None when the cursor is not on a local. Reuses the same target_at resolution as go-to-definition / references, so hover cannot disagree with them.