tests/integration/fee_estimate_query_e2e_test.py (1)

49-65: ⚠️ Potential issue | 🟡 Minor | ⚡ Quick win

Fix typo and improve test structure.

Same typo issue (chuck_tx → chunk_tx). Remove print() and add meaningful assertions for chunked transaction fee aggregation.

Proposed fix

 `@pytest.mark.integration`
-def test_can_execute_fee_estimation_query_chuck_tx(env):
-
+def test_fee_estimation_query_topic_message_chunked(env):
     tx = (
         TopicMessageSubmitTransaction().set_topic_id(TopicId(0, 0, 2)).set_chunk_size(10).set_message("s" * 20)
     )  # 2 chunks
 
-    # 2. IMPORTANT: Let freeze_with generate the valid transaction ID sequence
-    # This ensures tx._transaction_ids is populated correctly.
-
     tx.freeze_with(env.client)
     query = FeeEstimateQuery().set_mode(FeeEstimateMode.STATE).set_transaction(tx)
     result = query.execute(env.client)
 
-    print(result)
     assert result is not None
+    assert result.total > 0, "Chunked transaction should have positive fee total"
+    assert result.node_fee is not None, "Should include node fee breakdown"
+    assert result.service_fee is not None, "Should include service fee breakdown"

src/hiero_sdk_python/query/fee_estimate_query.py (1)

300-309: ⚠️ Potential issue | 🔴 Critical | ⚡ Quick win

Same isinstance() syntax error with union types.

This line has the same issue as line 102 - union types with | are not valid in isinstance().

Proposed fix

     def _is_chunked(self) -> bool:
         from hiero_sdk_python.consensus.topic_message_submit_transaction import (
             TopicMessageSubmitTransaction,
         )
         from hiero_sdk_python.file.file_append_transaction import (
             FileAppendTransaction,
         )
 
-        return isinstance(self._transaction, (TopicMessageSubmitTransaction | FileAppendTransaction))
+        return isinstance(self._transaction, (TopicMessageSubmitTransaction, FileAppendTransaction))

src/hiero_sdk_python/consensus/topic_message_submit_transaction.py (2)

204-209: ⚠️ Potential issue | 🔴 Critical | ⚡ Quick win

BLOCKER: Guard initialTransactionID before multi-chunk serialization.

When _total_chunks > 1, self._initial_transaction_id._to_proto() can dereference None if chunk metadata wasn’t initialized first. Add an explicit guard and raise a descriptive ValueError.

Proposed fix

         # Multi-chunk metadata
         if self._total_chunks > 1:
+            if self._initial_transaction_id is None:
+                raise ValueError(
+                    "initial transaction ID is missing for multi-chunk submit; call freeze_with(client) first."
+                )
             body.chunkInfo.CopyFrom(
                 consensus_submit_message_pb2.ConsensusMessageChunkInfo(
                     initialTransactionID=self._initial_transaction_id._to_proto(),
                     total=self._total_chunks,
                     number=self._current_chunk_index + 1,
                 )
             )

As per coding guidelines, "_build_proto_body() calls self._initial_transaction_id._to_proto() when _total_chunks > 1 ... an explicit guard with a descriptive ValueError MUST be present."

---

269-271: ⚠️ Potential issue | 🔴 Critical | ⚡ Quick win

BLOCKER: Timestamp.nanos overflow is not handled when generating chunk transaction IDs.

nanos=base_timestamp.nanos + i can exceed protobuf bounds (999_999_999) for large chunk counts. Carry overflow into seconds.

Proposed fix

                 else:
+                    total_nanos = base_timestamp.nanos + i
                     chunk_valid_start = timestamp_pb2.Timestamp(
-                        seconds=base_timestamp.seconds, nanos=base_timestamp.nanos + i
+                        seconds=base_timestamp.seconds + total_nanos // 1_000_000_000,
+                        nanos=total_nanos % 1_000_000_000,
                     )
                     chunk_transaction_id = TransactionId(
                         account_id=self.transaction_id.account_id, valid_start=chunk_valid_start
                     )

As per coding guidelines, "the expression base_timestamp.nanos + i MUST be checked for overflow ... An overflow guard MUST carry seconds over."