fix: tolerate runtime schema drift

internal/workflow/store_test.go

@@ -46,6 +46,19 @@ func TestStoreBuildsDynamicEventsWithoutFixedRoles(t *testing.T) {
 	}
 }
 
+func TestStoreNilRuntimeReturnsEmptyLowConfidenceView(t *testing.T) {
+	view, err := Store{WorkspaceRoot: t.TempDir()}.View()
+	if err != nil {
+		t.Fatalf("View returned error: %v", err)
+	}
+	if len(view.Events) != 0 || len(view.HandoffEdges) != 0 || len(view.Phases) != 0 {
+		t.Fatalf("expected empty view, got %#v", view)
+	}
+	if view.Source.Kind != "runtime_missing" || view.Source.Confidence != "low" {
+		t.Fatalf("unexpected source: %#v", view.Source)
+	}
+}
+
 type StaticRuntime struct {
 	SnapshotValue runtime.Snapshot
 }