diff --git a/workflows.go b/workflows.go
index 26c98d1..45d92af 100644
--- a/workflows.go
+++ b/workflows.go
@@ -62,7 +62,6 @@ const (
 type WorkflowTimerUnit string
 
 const (
-	WorkflowTimerUnitSeconds WorkflowTimerUnit = "s"
 	WorkflowTimerUnitMinutes WorkflowTimerUnit = "m"
 	WorkflowTimerUnitHours   WorkflowTimerUnit = "h"
 	WorkflowTimerUnitDays    WorkflowTimerUnit = "d"
@@ -197,9 +196,9 @@ type SimplifiedContactPropertyTriggerWorkflowNode struct {
 // SimplifiedAddToListTriggerWorkflowNode is the AddToListTrigger variant of
 // [SimplifiedWorkflowNode].
 type SimplifiedAddToListTriggerWorkflowNode struct {
-	NextNodeIDs []string `json:"nextNodeIds"`
-	MailingList string   `json:"mailingList,omitempty"`
-	ReEligible  *bool    `json:"reEligible,omitempty"`
+	NextNodeIDs   []string `json:"nextNodeIds"`
+	MailingListID *string  `json:"mailingListId"`
+	ReEligible    *bool    `json:"reEligible,omitempty"`
 }
 
 // SimplifiedBlankTriggerWorkflowNode is the BlankTrigger variant of
@@ -439,10 +438,11 @@ type ContactPropertyTriggerWorkflowNode struct {
 // AddToListTriggerWorkflowNode is the AddToListTrigger variant of
 // [WorkflowNode].
 type AddToListTriggerWorkflowNode struct {
-	ID          string   `json:"id"`
-	WorkflowID  string   `json:"workflowId"`
-	NextNodeIDs []string `json:"nextNodeIds"`
-	ReEligible  bool     `json:"reEligible"`
+	ID            string   `json:"id"`
+	WorkflowID    string   `json:"workflowId"`
+	NextNodeIDs   []string `json:"nextNodeIds"`
+	MailingListID *string  `json:"mailingListId"`
+	ReEligible    bool     `json:"reEligible"`
 }
 
 // BlankTriggerWorkflowNode is the BlankTrigger variant of [WorkflowNode].
@@ -471,14 +471,13 @@ type TimerActionWorkflowNode struct {
 	Unit        WorkflowTimerUnit `json:"unit"`
 }
 
-// SendEmailActionWorkflowNode is the SendEmailAction variant of
-// [WorkflowNode]. The full variant does not include emailMessageId (only the
-// simplified variant does).
+// SendEmailActionWorkflowNode is the SendEmailAction variant of [WorkflowNode].
 type SendEmailActionWorkflowNode struct {
-	ID          string   `json:"id"`
-	WorkflowID  string   `json:"workflowId"`
-	NextNodeIDs []string `json:"nextNodeIds"`
-	Subject     string   `json:"subject,omitempty"`
+	ID             string   `json:"id"`
+	WorkflowID     string   `json:"workflowId"`
+	NextNodeIDs    []string `json:"nextNodeIds"`
+	EmailMessageID string   `json:"emailMessageId"`
+	Subject        string   `json:"subject"`
 }
 
 // ExitActionWorkflowNode is the ExitAction variant of [WorkflowNode].
@@ -649,13 +648,16 @@ func marshalDiscriminated(typeName string, inner any) ([]byte, error) {
 	if typeName == "" {
 		return nil, fmt.Errorf("workflow node: typeName is empty")
 	}
-	if inner == nil {
-		return nil, fmt.Errorf("workflow node: %s variant is nil", typeName)
-	}
 	raw, err := json.Marshal(inner)
 	if err != nil {
 		return nil, err
 	}
+	// A typed-nil variant pointer is a non-nil interface but marshals to
+	// "null"; treat that (and an untyped nil) as a missing variant instead of
+	// panicking on the nil map below.
+	if string(raw) == "null" {
+		return nil, fmt.Errorf("workflow node: %s variant is nil", typeName)
+	}
 	var fields map[string]json.RawMessage
 	if err := json.Unmarshal(raw, &fields); err != nil {
 		return nil, err
diff --git a/workflows_test.go b/workflows_test.go
index d88b6f7..819f7d3 100644
--- a/workflows_test.go
+++ b/workflows_test.go
@@ -1230,3 +1230,82 @@ func TestCreatedWorkflowNode_MarshalKeepsRevisionAndChildren(t *testing.T) {
 		t.Errorf("marshal dropped createdChildNodes: %s", raw)
 	}
 }
+
+func TestGetWorkflowNode_AddToListTrigger(t *testing.T) {
+	body := `{
+		"id": "node_a",
+		"workflowId": "wf_1",
+		"typeName": "AddToListTrigger",
+		"nextNodeIds": ["node_next"],
+		"mailingListId": "ml_1",
+		"reEligible": true
+	}`
+	server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		w.Write([]byte(body))
+	}))
+	defer server.Close()
+
+	client := NewClient("test-key", WithBaseURL(server.URL))
+	node, err := client.GetWorkflowNode("wf_1", "node_a")
+	if err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+	if node.AddToListTrigger == nil {
+		t.Fatal("AddToListTrigger is nil")
+	}
+	if node.AddToListTrigger.MailingListID == nil || *node.AddToListTrigger.MailingListID != "ml_1" {
+		t.Errorf("MailingListID = %v, want ml_1", node.AddToListTrigger.MailingListID)
+	}
+}
+
+func TestGetWorkflowNode_SendEmailAction(t *testing.T) {
+	body := `{
+		"id": "node_s",
+		"workflowId": "wf_1",
+		"typeName": "SendEmailAction",
+		"nextNodeIds": ["node_next"],
+		"emailMessageId": "em_1",
+		"subject": "Welcome"
+	}`
+	server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		w.Write([]byte(body))
+	}))
+	defer server.Close()
+
+	client := NewClient("test-key", WithBaseURL(server.URL))
+	node, err := client.GetWorkflowNode("wf_1", "node_s")
+	if err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+	if node.SendEmailAction == nil {
+		t.Fatal("SendEmailAction is nil")
+	}
+	if node.SendEmailAction.EmailMessageID != "em_1" {
+		t.Errorf("EmailMessageID = %q, want em_1", node.SendEmailAction.EmailMessageID)
+	}
+	if node.SendEmailAction.Subject != "Welcome" {
+		t.Errorf("Subject = %q, want Welcome", node.SendEmailAction.Subject)
+	}
+}
+
+func TestSimplifiedAddToListNode_DecodesMailingListID(t *testing.T) {
+	const in = `{"typeName":"AddToListTrigger","nextNodeIds":[],"mailingListId":"ml_1","reEligible":true}`
+	var n SimplifiedWorkflowNode
+	if err := json.Unmarshal([]byte(in), &n); err != nil {
+		t.Fatalf("Unmarshal: %v", err)
+	}
+	if n.AddToListTrigger == nil {
+		t.Fatal("AddToListTrigger is nil")
+	}
+	if n.AddToListTrigger.MailingListID == nil || *n.AddToListTrigger.MailingListID != "ml_1" {
+		t.Errorf("MailingListID = %v, want ml_1", n.AddToListTrigger.MailingListID)
+	}
+}
+
+func TestMarshalDiscriminated_TypedNilVariantErrors(t *testing.T) {
+	// A node with the discriminator set but the variant pointer nil must return
+	// an error, not panic on a nil-map write.
+	if _, err := json.Marshal(WorkflowNode{TypeName: WorkflowNodeTypeTimerAction}); err == nil {
+		t.Fatal("expected error marshaling a node with a nil variant, got none")
+	}
+}