fix(models): preserve streamed content part order

src/agents/models/chatcmpl_stream_handler.py

@@ -1119,10 +1119,15 @@ async def handle_stream(
             )
             if state.provider_data:
                 assistant_msg.provider_data = state.provider_data.copy()  # type: ignore[attr-defined]
+
+            content_parts: list[tuple[int, ResponseOutputText | ResponseOutputRefusal]] = []
             if state.text_content_index_and_output:
-                assistant_msg.content.append(state.text_content_index_and_output[1])
+                content_parts.append(state.text_content_index_and_output)
             if state.refusal_content_index_and_output:
-                assistant_msg.content.append(state.refusal_content_index_and_output[1])
+                content_parts.append(state.refusal_content_index_and_output)
+            assistant_msg.content.extend(
+                part for _, part in sorted(content_parts, key=lambda item: item[0])
+            )
             outputs.append(assistant_msg)
 
             # send a ResponseOutputItemDone for the assistant message

tests/models/test_openai_chatcompletions_stream.py

@@ -790,21 +790,30 @@ async def test_stream_handler_places_text_after_existing_refusal_part() -> None:
 
     events = await _collect_handler_events(*chunks)
 
+    refusal_part_added = next(
+        event
+        for event in events
+        if event.type == "response.content_part.added"
+        and isinstance(event.part, ResponseOutputRefusal)
+    )
     text_part_added = next(
         event
         for event in events
         if event.type == "response.content_part.added"
         and isinstance(event.part, ResponseOutputText)
     )
+    assert refusal_part_added.content_index == 0
     assert text_part_added.content_index == 1
 
     completed_event = next(event for event in events if event.type == "response.completed")
     assistant_item = completed_event.response.output[0]
     assert isinstance(assistant_item, ResponseOutputMessage)
-    assert isinstance(assistant_item.content[0], ResponseOutputText)
-    assert isinstance(assistant_item.content[1], ResponseOutputRefusal)
-    assert assistant_item.content[0].text == "partial"
-    assert assistant_item.content[1].refusal == "blocked"
+    assert isinstance(
+        assistant_item.content[refusal_part_added.content_index], ResponseOutputRefusal
+    )
+    assert isinstance(assistant_item.content[text_part_added.content_index], ResponseOutputText)
+    assert assistant_item.content[refusal_part_added.content_index].refusal == "blocked"
+    assert assistant_item.content[text_part_added.content_index].text == "partial"
 
 
 @pytest.mark.allow_call_model_methods