diff --git a/internal/serviceadapter/workflow_adapter.go b/internal/serviceadapter/workflow_adapter.go
index 9f18414..773404e 100644
--- a/internal/serviceadapter/workflow_adapter.go
+++ b/internal/serviceadapter/workflow_adapter.go
@@ -134,8 +134,13 @@ func (wa *WorkflowAdapter) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 
 	// Inject action into body for temporal handler
 	payload["action"] = action
-	if _, ok := payload["namespace"]; !ok {
-		payload["namespace"] = "default"
+
+	// namespace is required for all workflow operations
+	if ns, ok := payload["namespace"].(string); !ok || ns == "" {
+		w.Header().Set("Content-Type", "application/json")
+		w.WriteHeader(http.StatusBadRequest)
+		fmt.Fprintf(w, `{"error":"namespace is required"}`)
+		return
 	}
 
 	newBody, _ := json.Marshal(payload)