diff --git a/lib/foundation/fabro-types/src/graph.rs b/lib/foundation/fabro-types/src/graph.rs
index 9fdec1ff2..e2ed3fab4 100644
--- a/lib/foundation/fabro-types/src/graph.rs
+++ b/lib/foundation/fabro-types/src/graph.rs
@@ -155,9 +155,14 @@ impl Node {
     /// enclosing subgraphs, and import placeholders — so every caller needs the
     /// same de-duplicating append.
     ///
+    /// The name is trimmed, and a name that is empty or only whitespace is
+    /// dropped. Stylesheet selectors match class names exactly, so a padded
+    /// name would never match any rule.
+    ///
     /// Order is preserved because the first class is meaningful: it supplies
     /// the fallback thread ID for fidelity threading.
     pub fn add_class(&mut self, class: &str) {
+        let class = class.trim();
         if !class.is_empty() && !self.classes.iter().any(|existing| existing == class) {
             self.classes.push(class.to_string());
         }
@@ -684,6 +689,18 @@ mod tests {
         assert!(node.project_memory());
     }
 
+    #[test]
+    fn add_class_trims_names_and_drops_blanks_and_duplicates() {
+        let mut node = Node::new("work");
+        node.add_class("coding");
+        node.add_class(" coding ");
+        node.add_class("");
+        node.add_class("   ");
+        node.add_class("\tcritical\n");
+
+        assert_eq!(node.classes, ["coding", "critical"]);
+    }
+
     fn node_with(id: &str, attrs: &[(&str, &str)]) -> Node {
         let mut node = Node::new(id);
         for (key, value) in attrs {