fix: Rename memo field to topicMemo to eliminate name collision

src/hiero_sdk_python/consensus/topic_create_transaction.py

@@ -63,7 +63,7 @@ def __init__(
             fee_exempt_keys (list[Key], optional): Optional list of fee exempt keys for the topic (PrivateKey or PublicKey).
         """
         super().__init__()
-        self.memo: str = memo or ""
+        self.topic_memo: str = memo or ""
         self.admin_key: Key | None = admin_key
         self.submit_key: Key | None = submit_key
         self.auto_renew_period: Duration = auto_renew_period or Duration(7890000)
@@ -84,7 +84,7 @@ def set_memo(self, memo: str) -> TopicCreateTransaction:
             TopicCreateTransaction: The current instance for method chaining.
         """
         self._require_not_frozen()
-        self.memo = memo
+        self.topic_memo = memo
         return self
 
     def set_admin_key(self, key: Key) -> TopicCreateTransaction:
@@ -237,7 +237,7 @@ def _build_proto_body(self) -> consensus_create_topic_pb2.ConsensusCreateTopicTr
             submitKey=key_to_proto(self.submit_key),
             autoRenewPeriod=(self.auto_renew_period._to_proto() if self.auto_renew_period is not None else None),
             autoRenewAccount=(self.auto_renew_account._to_proto() if self.auto_renew_account is not None else None),
-            memo=self.memo,
+            memo=self.topic_memo,
             custom_fees=[custom_fee._to_topic_fee_proto() for custom_fee in self.custom_fees],
             fee_schedule_key=key_to_proto(self.fee_schedule_key),
             fee_exempt_key_list=[key_to_proto(key) for key in self.fee_exempt_keys],

src/hiero_sdk_python/consensus/topic_update_transaction.py

@@ -57,7 +57,7 @@ def __init__(
         """
         super().__init__()
         self.topic_id: TopicId | None = topic_id
-        self.memo: str = memo or ""
+        self.topic_memo: str | None = memo
         self.admin_key: Key | None = admin_key
         self.submit_key: Key | None = submit_key
         self.auto_renew_period: Duration | None = auto_renew_period
@@ -93,7 +93,7 @@ def set_memo(self, memo: str) -> TopicUpdateTransaction:
             TopicUpdateTransaction: Returns the instance for method chaining.
         """
         self._require_not_frozen()
-        self.memo = memo
+        self.topic_memo = memo
         return self
 
     def set_admin_key(self, key: Key) -> TopicUpdateTransaction:
@@ -271,7 +271,7 @@ def _build_proto_body(self) -> consensus_update_topic_pb2.ConsensusUpdateTopicTr
             ),
             autoRenewAccount=(self.auto_renew_account._to_proto() if self.auto_renew_account else None),
             expirationTime=self.expiration_time._to_protobuf() if self.expiration_time else None,
-            memo=_wrappers_pb2.StringValue(value=self.memo) if self.memo is not None else None,
+            memo=_wrappers_pb2.StringValue(value=self.topic_memo) if self.topic_memo is not None else None,
             custom_fees=custom_fees,
             fee_schedule_key=key_to_proto(self.fee_schedule_key) if self.fee_schedule_key else None,
             fee_exempt_key_list=fee_exempt_key_list,

tests/unit/topic_create_transaction_test.py

@@ -328,7 +328,7 @@ def test_constructor(multiple_custom_fees, key_type, use_private):
         fee_exempt_keys=fee_exempt_keys,
     )
 
-    assert tx.memo == "Test Topic"
+    assert tx.topic_memo == "Test Topic"
     assert tx.admin_key == admin_key
     assert tx.submit_key == submit_key
     assert tx.custom_fees == multiple_custom_fees
@@ -339,7 +339,7 @@ def test_constructor(multiple_custom_fees, key_type, use_private):
 def test_constructor_default_values():
     """Test constructor with default values."""
     tx_default = TopicCreateTransaction()
-    assert tx_default.memo == ""
+    assert tx_default.topic_memo == ""
     assert tx_default.admin_key is None
     assert tx_default.submit_key is None
     assert tx_default.custom_fees == []
@@ -627,3 +627,27 @@ def test_freeze_with_leaves_auto_renew_account_unset_without_operator(mock_clien
     body = frozen_tx.build_transaction_body()
 
     assert not body.consensusCreateTopic.HasField("autoRenewAccount")
+
+
+def test_topic_memo_does_not_collide_with_transaction_memo():
+    """Regression test for: topic and transaction memos remain independent."""
+    tx = TopicCreateTransaction(memo="my topic memo")
+    assert tx.topic_memo == "my topic memo"
+    assert tx.memo == ""  # base Transaction-level memo defaults independently
+
+    tx.set_transaction_memo("some unrelated audit note")
+
+    assert tx.topic_memo == "my topic memo", "topic_memo was clobbered by set_transaction_memo()"
+    assert tx.memo == "some unrelated audit note"
+
+
+def test_topic_memo_reflected_in_protobuf_independent_of_transaction_memo(mock_client):
+    """Verify protobuf preserves separate topic and transaction memos."""
+    tx = TopicCreateTransaction(memo="my topic memo")
+    tx.set_transaction_memo("some unrelated audit note")
+    tx.transaction_id = TransactionId.generate(AccountId(0, 0, 1234))
+    frozen_tx = tx.freeze_with(mock_client)
+    body = frozen_tx.build_transaction_body()
+
+    assert body.consensusCreateTopic.memo == "my topic memo"
+    assert body.memo == "some unrelated audit note"

tests/unit/topic_update_transaction_test.py

@@ -359,3 +359,68 @@ def test_topic_update_transaction_with_all_fields(topic_id):
 
         # Verify the receipt contains the expected values
         assert receipt.status == ResponseCode.SUCCESS
+
+
+def test_topic_memo_and_transaction_memo_independent_in_protobuf(
+    mock_account_ids,
+    topic_id,
+):
+    """Topic and transaction memos serialize independently."""
+
+    _, _, node_account_id, _, _ = mock_account_ids
+
+    tx = TopicUpdateTransaction(
+        topic_id=topic_id,
+        memo="my topic memo",
+    )
+
+    tx.operator_account_id = AccountId(0, 0, 2)
+    tx.node_account_id = node_account_id
+
+    tx.set_transaction_memo("some unrelated audit note")
+
+    body = tx.build_transaction_body()
+
+    assert body.memo == "some unrelated audit note"
+    assert body.consensusUpdateTopic.memo.value == "my topic memo"
+
+
+def test_set_memo_updates_topic_memo_only():
+    """Verify set_memo() only updates the topic memo."""
+    tx = TopicUpdateTransaction()
+    tx.set_transaction_memo("audit note")
+    tx.set_memo("new topic memo")
+
+    assert tx.topic_memo == "new topic memo"
+    assert tx.memo == "audit note"
+
+
+def test_topic_memo_serialization_distinguishes_unset_and_empty(
+    mock_account_ids,
+    topic_id,
+):
+    """Unset and explicit empty topic memos serialize differently."""
+    _, _, node_account_id, _, _ = mock_account_ids
+
+    tx = TopicUpdateTransaction(topic_id=topic_id)
+    tx.operator_account_id = AccountId(0, 0, 2)
+    tx.node_account_id = node_account_id
+
+    body = tx.build_transaction_body().consensusUpdateTopic
+    assert not body.HasField("memo")
+
+    tx = TopicUpdateTransaction(topic_id=topic_id, memo="")
+    tx.operator_account_id = AccountId(0, 0, 2)
+    tx.node_account_id = node_account_id
+
+    body = tx.build_transaction_body().consensusUpdateTopic
+    assert body.HasField("memo")
+    assert body.memo.value == ""
+
+    tx = TopicUpdateTransaction(topic_id=topic_id, memo="hello")
+    tx.operator_account_id = AccountId(0, 0, 2)
+    tx.node_account_id = node_account_id
+
+    body = tx.build_transaction_body().consensusUpdateTopic
+    assert body.HasField("memo")
+    assert body.memo.value == "hello"