context.facets was an array, needs to be a record

packages/swingset-liveslots/src/virtualObjectManager.js

@@ -800,9 +800,12 @@ export function makeVirtualObjectManager(
     function makeContext(baseRef, state) {
       // baseRef came from valToSlot, so must be in slotToVal
       const val = requiredValForSlot(baseRef);
-      // val is either 'self' or 'facets'
+      // val is either 'self' or an array of facets
       if (multifaceted) {
-        return harden({ state, facets: val });
+        // but userspace needs a record of named facets
+        const facets = {};
+        facetNames.forEach((name, idx) => (facets[name] = val[idx]));
+        return harden({ state, facets });
       }
       return harden({ state, self: val });
     }

packages/swingset-liveslots/test/virtual-objects/test-facets.js

@@ -0,0 +1,23 @@
+import test from 'ava';
+import '@endo/init/debug.js';
+
+import { makeFakeVirtualObjectManager } from '../../tools/fakeVirtualSupport.js';
+
+test('facets', async t => {
+  const vom = makeFakeVirtualObjectManager();
+  const init = () => ({ value: 0 });
+  const behavior = {
+    mutable: {
+      set: ({ state }, value) => (state.value = value),
+      get: ({ state }) => state.value,
+      getImmutable: ({ facets }) => facets.immutable,
+    },
+    immutable: {
+      get: ({ state }) => state.value,
+    },
+  };
+  const makeThing = vom.defineKindMulti('thing', init, behavior);
+  const thing1 = makeThing();
+  thing1.mutable.set(1);
+  t.is(thing1.mutable.getImmutable(), thing1.immutable);
+});