diff --git a/internal/controllogic/engine_helpers_test.go b/internal/controllogic/engine_helpers_test.go
index 1ef5d05..59a51ad 100644
--- a/internal/controllogic/engine_helpers_test.go
+++ b/internal/controllogic/engine_helpers_test.go
@@ -87,7 +87,7 @@ func TestCoerceParamValue(t *testing.T) {
 }
 
 func TestSign(t *testing.T) {
-	if sign(5) != 1 || sign(-5) != -1 || sign(0) != 0 {
-		t.Errorf("sign mismatch: %d %d %d", sign(5), sign(-5), sign(0))
+	if signOf(5) != 1 || signOf(-5) != -1 || signOf(0) != 0 {
+		t.Errorf("sign mismatch: %d %d %d", signOf(5), signOf(-5), signOf(0))
 	}
 }
diff --git a/internal/controllogic/engine_test.go b/internal/controllogic/engine_test.go
index e43a148..e092784 100644
--- a/internal/controllogic/engine_test.go
+++ b/internal/controllogic/engine_test.go
@@ -60,6 +60,54 @@ func TestArrayClearNode(t *testing.T) {
 	}
 }
 
+func TestArraySetNode(t *testing.T) {
+	g := Graph{
+		ID: "g", Name: "n",
+		StateVars: []StateVar{{Name: "buf", Type: "array", Initial: "[0,0,0]", Sizing: "dynamic"}},
+		Nodes: []Node{
+			{ID: "t", Kind: "trigger.timer", Params: map[string]string{"interval": "1000"}},
+			{ID: "s", Kind: "action.array.set", Params: map[string]string{"array": "buf", "index": "1", "expr": "9"}},
+		},
+		Wires: []Wire{{From: "t", To: "s"}},
+	}
+	cg := runFlowOnce(t, g, "t")
+	if got := cg.getLocal("buf"); !reflect.DeepEqual(got, []Value{0.0, 9.0, 0.0}) {
+		t.Fatalf("after set buf = %#v", got)
+	}
+}
+
+func TestArrayRemoveNode(t *testing.T) {
+	g := Graph{
+		ID: "g", Name: "n",
+		StateVars: []StateVar{{Name: "buf", Type: "array", Initial: "[10,20,30]", Sizing: "dynamic"}},
+		Nodes: []Node{
+			{ID: "t", Kind: "trigger.timer", Params: map[string]string{"interval": "1000"}},
+			{ID: "r", Kind: "action.array.remove", Params: map[string]string{"array": "buf", "index": "-1"}},
+		},
+		Wires: []Wire{{From: "t", To: "r"}},
+	}
+	cg := runFlowOnce(t, g, "t")
+	if got := cg.getLocal("buf"); !reflect.DeepEqual(got, []Value{10.0, 20.0}) {
+		t.Fatalf("after remove buf = %#v", got)
+	}
+}
+
+func TestArrayPopNode(t *testing.T) {
+	g := Graph{
+		ID: "g", Name: "n",
+		StateVars: []StateVar{{Name: "buf", Type: "array", Initial: "[1,2,3]", Sizing: "dynamic"}},
+		Nodes: []Node{
+			{ID: "t", Kind: "trigger.timer", Params: map[string]string{"interval": "1000"}},
+			{ID: "p", Kind: "action.array.pop", Params: map[string]string{"array": "buf"}},
+		},
+		Wires: []Wire{{From: "t", To: "p"}},
+	}
+	cg := runFlowOnce(t, g, "t")
+	if got := cg.getLocal("buf"); !reflect.DeepEqual(got, []Value{1.0, 2.0}) {
+		t.Fatalf("after pop buf = %#v", got)
+	}
+}
+
 func TestCompileInitsLocalsFromDecls(t *testing.T) {
 	g := Graph{
 		ID: "g", Name: "n",
diff --git a/internal/controllogic/expr.go b/internal/controllogic/expr.go
index 367f53f..35aec4c 100644
--- a/internal/controllogic/expr.go
+++ b/internal/controllogic/expr.go
@@ -353,8 +353,6 @@ func signOf(x float64) int {
 	}
 }
 
-// sign is an alias for signOf, kept for backward compatibility with existing tests.
-func sign(x float64) int { return signOf(x) }
 func clampIdx(i, length int) int {
 	if i < 0 {
 		i = length + i