Function file_class_name 

pub fn file_class_name<'db>(db: &'db dyn Db, file: FileText) -> Option<SmolStr>

A file’s class_name, if it declares one — the offset-free projection of its item tree that global_registry depends on. It reads only item_tree(file).class_name (never a byte range), so a body edit re-runs item_tree but this query backdates (its value is unchanged), leaving the registry — and everything cross-file — undisturbed by a keystroke.