feat: add engine and store snapshot/restore for restart resilience

test/access.test.js

@@ -65,3 +65,13 @@ test("second unlock call is idempotent and does not double charge", () => {
 
   assert.equal(wallet.getBalance("u2"), 7);
 });
+
+test("restores grant state from snapshot", () => {
+  const access = new AudioAccessStore();
+  access.grantAccess("a1", "u2");
+
+  const restored = new AudioAccessStore(access.exportState());
+  const canAccess = restored.canAccess({ audio, userId: "u2" });
+  assert.equal(canAccess.allowed, true);
+  assert.equal(canAccess.reason, "grant");
+});