diff --git a/tests/rigor/fuzzer-mutation-needles.test.js b/tests/rigor/fuzzer-mutation-needles.test.js
index 171aa46..aa3065d 100644
--- a/tests/rigor/fuzzer-mutation-needles.test.js
+++ b/tests/rigor/fuzzer-mutation-needles.test.js
@@ -23,7 +23,7 @@ import { Arbiter } from '../../src/index.js';
 const NODES = 6;
 const nodeKey = (id) => (id < 2 ? `u:${id}` : id === 2 ? 'g:0' : `doc:${id - 3}`);
 
-const KINDS = ['direct', 'chain', 'union', 'exclusion'];
+const KINDS = ['direct', 'chain', 'union', 'exclusion', 'intersection', 'defeasible'];
 const CONFIGS = {
   direct: { type: 'direct', relation: 'owner' },
   chain: {
@@ -46,6 +46,18 @@ const CONFIGS = {
       { type: 'direct', relation: 'owner' },
       { type: 'chain', steps: [{ relation: 'member_of', direction: 'out' }, { relation: 'reads', direction: 'out' }] }
     ]
+  },
+  intersection: {
+    intersection: {
+      rules: [
+        { type: 'direct', relation: 'owner' },
+        { type: 'chain', steps: [{ relation: 'member_of', direction: 'out' }, { relation: 'reads', direction: 'out' }] }
+      ]
+    }
+  },
+  defeasible: {
+    when: { type: 'direct', relation: 'owner' },
+    unless: { type: 'chain', steps: [{ relation: 'member_of', direction: 'out' }, { relation: 'reads', direction: 'out' }] }
   }
 };
 
@@ -64,6 +76,8 @@ function mirrorCheck(tuples, kind, src, rel, dst) {
   if (kind === 'chain') return chainBest;
   if (kind === 'union') return Math.max(direct, chainBest);
   if (kind === 'exclusion') return direct * (1 - chainBest);
+  if (kind === 'intersection') return Math.min(direct, chainBest);
+  if (kind === 'defeasible') return direct * (1 - chainBest);
   return 0;
 }