Index: test/c2s-contacts.test.js
===================================================================
--- test/c2s-contacts.test.js	(revision 7922694b27fd0b9c421adfef80ab3c17ddde3a35)
+++ test/c2s-contacts.test.js	(revision 30871c19bf329fcc6ba2eb4c80c4450c11a044e8)
@@ -44,2 +44,12 @@
   assert.equal(ref.name, 'Dana');
 });
+
+test('prefersEnriched detects the Prefer opt-in (FEP-9876)', () => {
+  assert.equal(AP.prefersEnriched('return=representation'), true);
+  assert.equal(AP.prefersEnriched('return=representation; handling=lenient'), true);
+  assert.equal(AP.prefersEnriched('foo, return=representation'), true);
+  assert.equal(AP.prefersEnriched('return=minimal'), false);
+  assert.equal(AP.prefersEnriched('returnx=representation'), false);
+  assert.equal(AP.prefersEnriched(''), false);
+  assert.equal(AP.prefersEnriched(undefined), false);
+});