Python: [Feature]: Support OpenAI instructions in Responses API

python/packages/openai/agent_framework_openai/_chat_client.py

@@ -62,7 +62,6 @@
     TextSpanRegion,
     UsageDetails,
     detect_media_type_from_base64,
-    prepend_instructions_to_messages,
     validate_tool_mode,
 )
 from agent_framework.exceptions import (
@@ -1377,7 +1376,6 @@ async def _prepare_options(
             "logit_bias",  # not supported
             "seed",  # not supported
             "stop",  # not supported
-            "instructions",  # already added as system message
             "response_format",  # handled separately
             "conversation_id",  # handled separately
             "tool_choice",  # handled separately
@@ -1389,15 +1387,6 @@ async def _prepare_options(
             raise ChatClientInvalidRequestException(
                 "prompt_cache_options requires openai>=2.45.0; upgrade the openai package to use it."
             )
-
-        # messages
-        # Handle instructions by prepending to messages as system message
-        # Only prepend instructions for the first turn (when no conversation/response ID exists)
-        conversation_id = options.get("conversation_id")
-        if (instructions := options.get("instructions")) and not conversation_id:
-            # First turn: prepend instructions as system message
-            messages = prepend_instructions_to_messages(list(messages), instructions, role="system")
-        # Continuation turn: instructions already exist in conversation context, skip prepending
         request_uses_service_side_storage = False
         for key in ("conversation_id", "previous_response_id", "conversation"):
             value = options.get(key)

python/packages/openai/tests/openai/test_openai_chat_client.py

@@ -411,10 +411,14 @@ async def test_get_response_with_all_parameters() -> None:
     assert len(run_options["tools"]) == 1
     assert run_options["tools"][0]["type"] == "function"
     assert run_options["tools"][0]["name"] == "get_weather"
-    assert run_options["input"][0]["role"] == "system"
-    assert run_options["input"][0]["content"][0]["text"] == "You are a helpful assistant"
-    assert run_options["input"][1]["role"] == "user"
-    assert run_options["input"][1]["content"][0]["text"] == "Test message"
+
+    # Verify instructions are passed natively, not as a system message
+    assert run_options["instructions"] == "You are a helpful assistant"
+
+    # Verify the input only contains the user message
+    assert len(run_options["input"]) == 1
+    assert run_options["input"][0]["role"] == "user"
+    assert run_options["input"][0]["content"][0]["text"] == "Test message"
 
 
 @pytest.mark.asyncio
@@ -6196,70 +6200,30 @@ def _create_mock_responses_text_response(*, response_id: str) -> MagicMock:
     return mock_response
 
 
-async def test_instructions_sent_first_turn_then_skipped_for_continuation() -> None:
-    client = OpenAIChatClient(model="test-model", api_key="test-key")
-    mock_response = _create_mock_responses_text_response(response_id="resp_123")
-
-    with patch.object(client.client.responses, "create", return_value=mock_response) as mock_create:
-        await client.get_response(
-            messages=[Message(role="user", contents=["Hello"])],
-            options={"instructions": "Reply in uppercase."},
-        )
-
-        first_input_messages = mock_create.call_args.kwargs["input"]
-        assert len(first_input_messages) == 2
-        assert first_input_messages[0]["role"] == "system"
-        assert any("Reply in uppercase" in str(c) for c in first_input_messages[0]["content"])
-        assert first_input_messages[1]["role"] == "user"
-
-        await client.get_response(
-            messages=[Message(role="user", contents=["Tell me a joke"])],
-            options={
-                "instructions": "Reply in uppercase.",
-                "conversation_id": "resp_123",
-            },
-        )
-
-        second_input_messages = mock_create.call_args.kwargs["input"]
-        assert len(second_input_messages) == 1
-        assert second_input_messages[0]["role"] == "user"
-        assert not any(message["role"] == "system" for message in second_input_messages)
-
-
-@pytest.mark.parametrize("conversation_id", ["resp_456", "conv_abc123"])
-async def test_instructions_not_repeated_for_continuation_ids(
-    conversation_id: str,
+@pytest.mark.parametrize("conversation_id", [None, "resp_456", "conv_abc123"])
+async def test_instructions_passed_natively_not_as_system_message(
+    conversation_id: str | None,
 ) -> None:
+    """Test that instructions are passed to the Responses API natively and not prepended to messages."""
     client = OpenAIChatClient(model="test-model", api_key="test-key")
     mock_response = _create_mock_responses_text_response(response_id="resp_456")
 
     with patch.object(client.client.responses, "create", return_value=mock_response) as mock_create:
-        await client.get_response(
-            messages=[Message(role="user", contents=["Continue conversation"])],
-            options={"instructions": "Be helpful.", "conversation_id": conversation_id},
-        )
-
-        input_messages = mock_create.call_args.kwargs["input"]
-        assert len(input_messages) == 1
-        assert input_messages[0]["role"] == "user"
-        assert not any(message["role"] == "system" for message in input_messages)
+        options: OpenAIChatOptions = {"instructions": "Reply in uppercase."}
+        if conversation_id:
+            options["conversation_id"] = conversation_id
 
-
-async def test_instructions_included_without_conversation_id() -> None:
-    client = OpenAIChatClient(model="test-model", api_key="test-key")
-    mock_response = _create_mock_responses_text_response(response_id="resp_new")
-
-    with patch.object(client.client.responses, "create", return_value=mock_response) as mock_create:
         await client.get_response(
             messages=[Message(role="user", contents=["Hello"])],
-            options={"instructions": "You are a helpful assistant."},
+            options=options,
         )
 
+        assert mock_create.call_args.kwargs.get("instructions") == "Reply in uppercase."
+
         input_messages = mock_create.call_args.kwargs["input"]
-        assert len(input_messages) == 2
-        assert input_messages[0]["role"] == "system"
-        assert any("helpful assistant" in str(c) for c in input_messages[0]["content"])
-        assert input_messages[1]["role"] == "user"
+        assert len(input_messages) == 1
+        assert input_messages[0]["role"] == "user"
+        assert not any(message.get("role") == "system" for message in input_messages)
 
 
 def test_with_callable_api_key() -> None: