Avoid leaking realtime history list

Author: LocNguyenSGU

src/agents/realtime/session.py

@@ -186,7 +186,7 @@ async def __aenter__(self) -> RealtimeSession:
         # Emit initial history update
         await self._put_event(
             RealtimeHistoryUpdated(
-                history=self._history,
+                history=list(self._history),
                 info=self._event_info,
             )
         )
@@ -290,7 +290,7 @@ async def on_event(self, event: RealtimeModelEvent) -> None:
                 await self._put_event(RealtimeHistoryAdded(info=self._event_info, item=new_item))
             else:
                 await self._put_event(
-                    RealtimeHistoryUpdated(info=self._event_info, history=self._history)
+                    RealtimeHistoryUpdated(info=self._event_info, history=list(self._history))
                 )
         elif event.type == "input_audio_timeout_triggered":
             await self._put_event(
@@ -314,7 +314,7 @@ async def on_event(self, event: RealtimeModelEvent) -> None:
                 ),
             )
             await self._put_event(
-                RealtimeHistoryUpdated(info=self._event_info, history=self._history)
+                RealtimeHistoryUpdated(info=self._event_info, history=list(self._history))
             )
 
             # Check if we should run guardrails based on debounce threshold
@@ -387,13 +387,13 @@ async def on_event(self, event: RealtimeModelEvent) -> None:
                 await self._put_event(RealtimeHistoryAdded(info=self._event_info, item=new_item))
             else:
                 await self._put_event(
-                    RealtimeHistoryUpdated(info=self._event_info, history=self._history)
+                    RealtimeHistoryUpdated(info=self._event_info, history=list(self._history))
                 )
         elif event.type == "item_deleted":
             deleted_id = event.item_id
             self._history = [item for item in self._history if item.item_id != deleted_id]
             await self._put_event(
-                RealtimeHistoryUpdated(info=self._event_info, history=self._history)
+                RealtimeHistoryUpdated(info=self._event_info, history=list(self._history))
             )
         elif event.type == "connection_status":
             pass

tests/realtime/test_session.py

@@ -590,6 +590,27 @@ async def test_transcript_delta_updates_history_and_emits_history_updated(
         updated_history_item = cast(AssistantMessageItem, history_event.history[0])
         assert cast(AssistantAudio, updated_history_item.content[0]).transcript == "hello"
 
+    @pytest.mark.asyncio
+    async def test_transcript_delta_history_updated_uses_list_snapshot(
+        self, mock_model, mock_agent
+    ):
+        session = RealtimeSession(mock_model, mock_agent, None)
+
+        await session.on_event(
+            RealtimeModelTranscriptDeltaEvent(
+                item_id="item_1", delta="hello", response_id="resp_1"
+            )
+        )
+
+        await session._event_queue.get()  # raw event
+        history_event = await session._event_queue.get()
+        assert isinstance(history_event, RealtimeHistoryUpdated)
+
+        history_event.history.clear()
+
+        assert len(session._history) == 1
+        assert session._history[0].item_id == "item_1"
+
     @pytest.mark.asyncio
     async def test_ignored_events_only_generate_raw_events(self, mock_model, mock_agent):
         """Test that ignored events (connection_status, other) only generate raw events"""