diff --git a/agent-node/src/agent_node/core/watcher.py b/agent-node/src/agent_node/core/watcher.py
index e0e7a4c..191d912 100644
--- a/agent-node/src/agent_node/core/watcher.py
+++ b/agent-node/src/agent_node/core/watcher.py
@@ -141,7 +141,7 @@
                         "compressed": True,
                         "hash": hasher.hexdigest() if is_final else "",
                     }
-                    if hasattr(agent_pb2.FilePayload, "total_chunks"):
+                    if "total_chunks" in agent_pb2.FilePayload.DESCRIPTOR.fields_by_name:
                         payload_fields["total_chunks"] = total_chunks
                         payload_fields["total_size"] = file_size
 
diff --git a/agent-node/src/agent_node/node.py b/agent-node/src/agent_node/node.py
index 017e3b3..dbf8cd7 100644
--- a/agent-node/src/agent_node/node.py
+++ b/agent-node/src/agent_node/node.py
@@ -775,7 +775,7 @@
                         "compressed": True,
                     }
                     # Only add new fields if supported by the compiled proto
-                    if hasattr(agent_pb2.FilePayload, "total_chunks"):
+                    if "total_chunks" in agent_pb2.FilePayload.DESCRIPTOR.fields_by_name:
                         payload_fields["total_chunks"] = total_chunks
                         payload_fields["total_size"] = file_size
 
diff --git a/ai-hub/app/core/grpc/services/assistant.py b/ai-hub/app/core/grpc/services/assistant.py
index 7867de1..41257b4 100644
--- a/ai-hub/app/core/grpc/services/assistant.py
+++ b/ai-hub/app/core/grpc/services/assistant.py
@@ -100,7 +100,7 @@
                         "offset": offset,
                         "compressed": True,
                     }
-                    if hasattr(agent_pb2.FilePayload, "total_chunks"):
+                    if "total_chunks" in agent_pb2.FilePayload.DESCRIPTOR.fields_by_name:
                         payload_fields["total_chunks"] = total_chunks
                         payload_fields["total_size"] = file_size