Function registry_lookup 

pub fn registry_lookup(name: &str) -> Option<(ValueGrammar, DirectiveStatus)>

Looks up a directive name in the CSP3 directive registry. ASCII-case-insensitive, per CSP3’s directive-name matching rule (see plan/02-directive-splitting.md). Returns None for unregistered names – per CSP3’s forward-compatibility design, that is not itself a syntax error (see plan/DECISIONS.md, 2026-08-22).