fix(example): avoid duplicate streamed response deltas (#2285)

Author: abetlen

examples/server/server.py

@@ -8695,15 +8695,15 @@ def _ensure_reasoning_stream_item(
                 state,
                 "response.output_item.added",
                 output_index=item_state.output_index,
-                item=item,
+                item=copy.deepcopy(item),
             ),
             self._response_event(
                 state,
                 "response.content_part.added",
                 item_id=cast(str, item["id"]),
                 output_index=item_state.output_index,
                 content_index=0,
-                part=part,
+                part=copy.deepcopy(part),
             ),
         ], item_state
 
@@ -8727,15 +8727,15 @@ def _ensure_message_stream_item(
                 state,
                 "response.output_item.added",
                 output_index=item_state.output_index,
-                item=item,
+                item=copy.deepcopy(item),
             ),
             self._response_event(
                 state,
                 "response.content_part.added",
                 item_id=cast(str, item["id"]),
                 output_index=item_state.output_index,
                 content_index=0,
-                part=part,
+                part=copy.deepcopy(part),
             ),
         ], item_state
 
@@ -8777,7 +8777,7 @@ def _ensure_tool_stream_item(
                 state,
                 "response.output_item.added",
                 output_index=item_state.output_index,
-                item=item,
+                item=copy.deepcopy(item),
             )
         ], item_state