diff --git a/modules/nats/cmd/nats-tools/manifest_test.go b/modules/nats/cmd/nats-tools/manifest_test.go
index 632e74c6..84c98aa9 100644
--- a/modules/nats/cmd/nats-tools/manifest_test.go
+++ b/modules/nats/cmd/nats-tools/manifest_test.go
@@ -232,6 +232,11 @@ func TestTheBussManifestMountsItsProgramsIntoTheUpstreamImage(t *testing.T) {
 	if err := json.Unmarshal(raw, &whole); err != nil {
 		t.Fatal(err)
 	}
+	for _, st := range whole.State {
+		if (st.Name == "spent") != st.ReadOnly {
+			t.Errorf("the SDK reads %s read-only %v: spent alone is read-only", st.Name, st.ReadOnly)
+		}
+	}
 	if b := whole.ProcessBuses()["keeper"]; !b.Keeps {
 		t.Errorf("the keeper's bus declares no keeps, so it would be composed no bus state to keep (ADR 0626 §1): %+v", b)
 	}