update

backend/app/smartlead_client.py

@@ -152,9 +152,12 @@ class SmartleadClient:
         return self._make_request("POST", f"/campaigns/{campaign_id}/sequences", data)
     
     def add_leads_to_campaign(self, campaign_id: str, leads: List[Dict]) -> Dict:
-        """Add leads to a campaign"""
+        """Add leads to a campaign
+        
+        Smartlead API expects "lead_list" parameter, not "leads"
+        """
         data = {
-            "leads": leads
+            "lead_list": leads  # API expects "lead_list", not "leads"
         }
         return self._make_request("POST", f"/campaigns/{campaign_id}/leads", data)