Function contract_clause_kind 

pub fn contract_clause_kind(line: &str) -> Option<bool>

v0.124 (slice 3): the cursor sits in a contract-clause predicate — requires <name>: <cursor> or ensures <name>: <cursor> — where the enclosing function’s parameters (and, for an ensures, result) are in scope. Returns Some(is_ensures); the parameters themselves are resolved handler-side from the enclosing fn (needs the cursor offset).