Various pre-release cosmetic fixes

src/lib.rs

@@ -84,7 +84,7 @@ mod smoke {
     #[test]
     fn levels_generate_canonical_yaml() {
         let registry = levels::registry();
-        assert_eq!(registry.len(), 2);
+        assert_eq!(registry.len(), 3);
 
         // Level 1: any null-equivalent passes via the semantic short-circuit.
         let g1 = registry[0].generate(0);
@@ -110,5 +110,21 @@ mod smoke {
             g2.target_yaml, g2_again.target_yaml,
             "same seed should produce the same target"
         );
+
+        // Level 3: deterministic per seed; produces a mapping of mappings,
+        // each inner mapping has a `type` key.
+        let g3 = registry[2].generate(123);
+        let v3: serde_yaml::Value = serde_yaml::from_str(&g3.target_yaml).unwrap();
+        let m3 = v3.as_mapping().expect("level 3 produces a mapping");
+        assert!(!m3.is_empty());
+        for (_dir, feature) in m3 {
+            let inner = feature.as_mapping().expect("level 3 inner is a mapping");
+            assert!(
+                inner.get(serde_yaml::Value::String("type".into())).is_some(),
+                "each direction must carry a `type` key"
+            );
+        }
+        let g3_again = registry[2].generate(123);
+        assert_eq!(g3.target_yaml, g3_again.target_yaml);
     }
 }