Function semantic_tokens 

pub fn semantic_tokens(
    index: &ProjectIndex,
    local_tokens: &[(Span, bool)],
    path: &Path,
    text: &str,
    range: Option<Span>,
) -> Vec<SemanticToken>

Semantic tokens for path, delta-encoded over the frozen legend — a pure read of the cached index’s two sources: symbols (user defs+refs; a def site carries declaration) and foreign_refs (first-party references). range (byte offsets into text, the analysed snapshot) filters to overlapping tokens for the …/range request; None is the full document.