[gpt-oss][2/N] Support input_messages in responsesRequest

tests/entrypoints/openai/test_response_api_with_harmony.py

@@ -535,11 +535,17 @@ def get_place_to_travel():
     return "Paris"
 
 
+def get_horoscope(sign):
+    return f"{sign}: Next Tuesday you will befriend a baby otter."
+
+
 def call_function(name, args):
     if name == "get_weather":
         return get_weather(**args)
     elif name == "get_place_to_travel":
         return get_place_to_travel()
+    elif name == "get_horoscope":
+        return get_horoscope(**args)
     else:
         raise ValueError(f"Unknown function: {name}")
 
@@ -828,3 +834,103 @@ async def test_output_messages_enabled(client: OpenAI, model_name: str, server):
     assert response.status == "completed"
     assert len(response.input_messages) > 0
     assert len(response.output_messages) > 0
+
+
+@pytest.mark.asyncio
+@pytest.mark.parametrize("model_name", [MODEL_NAME])
+async def test_function_call_with_previous_input_messages(
+    client: OpenAI, model_name: str
+):
+    """Test function calling using previous_input_messages
+    for multi-turn conversation with a function call"""
+
+    # Define the get_horoscope tool
+    tools = [
+        {
+            "type": "function",
+            "name": "get_horoscope",
+            "description": "Get today's horoscope for an astrological sign.",
+            "parameters": {
+                "type": "object",
+                "properties": {
+                    "sign": {"type": "string"},
+                },
+                "required": ["sign"],
+                "additionalProperties": False,
+            },
+            "strict": True,
+        }
+    ]
+
+    # Step 1: First call with the function tool
+    stream_response = await client.responses.create(
+        model=model_name,
+        input="What is the horoscope for Aquarius today?",
+        tools=tools,
+        extra_body={"enable_response_messages": True},
+        stream=True,
+    )
+
+    response = None
+    async for event in stream_response:
+        if event.type == "response.completed":
+            response = event.response
+
+    assert response is not None
+    assert response.status == "completed"
+
+    # Step 2: Parse the first output to find the function_call type
+    function_call = None
+    for item in response.output:
+        if item.type == "function_call":
+            function_call = item
+            break
+
+    assert function_call is not None, "Expected a function_call in the output"
+    assert function_call.name == "get_horoscope"
+    assert function_call.call_id is not None
+
+    # Verify the format matches expectations
+    args = json.loads(function_call.arguments)
+    assert "sign" in args
+
+    # Step 3: Call the get_horoscope function
+    result = call_function(function_call.name, args)
+    assert "Aquarius" in result
+    assert "baby otter" in result
+
+    # Get the input_messages and output_messages from the first response
+    first_input_messages = response.input_messages
+    first_output_messages = response.output_messages
+
+    # Construct the full conversation history using previous_input_messages
+    previous_messages = (
+        first_input_messages
+        + first_output_messages
+        + [
+            {
+                "role": "tool",
+                "name": "functions.get_horoscope",
+                "content": [{"type": "text", "text": str(result)}],
+                "content_type": "<|constrain|>json",
+            }
+        ]
+    )
+
+    # Step 4: Make another responses.create() call with previous_input_messages
+    response_2 = await client.responses.create(
+        model=model_name,
+        tools=tools,
+        input="",
+        extra_body={"previous_input_messages": previous_messages},
+    )
+
+    assert response_2 is not None
+    assert response_2.status == "completed"
+    assert response_2.output_text is not None
+
+    # Verify the output makes sense - should contain information about the horoscope
+    output_text = response_2.output_text.lower()
+    assert (
+        "aquarius" in output_text or "otter" in output_text or "tuesday" in output_text
+    )

tests/entrypoints/test_harmony_utils.py

@@ -0,0 +1,254 @@
+# SPDX-License-Identifier: Apache-2.0
+# SPDX-FileCopyrightText: Copyright contributors to the vLLM project
+
+from openai_harmony import Role
+
+from vllm.entrypoints.harmony_utils import parse_input_to_harmony_message
+
+
+class TestParseInputToHarmonyMessage:
+    """Tests for parse_input_to_harmony_message function."""
+
+    def test_assistant_message_with_tool_calls(self):
+        """Test parsing assistant message with tool calls."""
+        chat_msg = {
+            "role": "assistant",
+            "tool_calls": [
+                {
+                    "function": {
+                        "name": "get_weather",
+                        "arguments": '{"location": "San Francisco"}',
+                    }
+                },
+                {
+                    "function": {
+                        "name": "search_web",
+                        "arguments": '{"query": "latest news"}',
+                    }
+                },
+            ],
+        }
+
+        messages = parse_input_to_harmony_message(chat_msg)
+
+        assert len(messages) == 2
+
+        # First tool call
+        assert messages[0].author.role == Role.ASSISTANT
+        assert messages[0].content[0].text == '{"location": "San Francisco"}'
+        assert messages[0].channel == "commentary"
+        assert messages[0].recipient == "functions.get_weather"
+        assert messages[0].content_type == "json"
+
+        # Second tool call
+        assert messages[1].author.role == Role.ASSISTANT
+        assert messages[1].content[0].text == '{"query": "latest news"}'
+        assert messages[1].channel == "commentary"
+        assert messages[1].recipient == "functions.search_web"
+        assert messages[1].content_type == "json"
+
+    def test_assistant_message_with_empty_tool_call_arguments(self):
+        """Test parsing assistant message with tool call having None arguments."""
+        chat_msg = {
+            "role": "assistant",
+            "tool_calls": [
+                {
+                    "function": {
+                        "name": "get_current_time",
+                        "arguments": None,
+                    }
+                }
+            ],
+        }
+
+        messages = parse_input_to_harmony_message(chat_msg)
+
+        assert len(messages) == 1
+        assert messages[0].content[0].text == ""
+        assert messages[0].recipient == "functions.get_current_time"
+
+    def test_tool_message_with_string_content(self):
+        """Test parsing tool message with string content."""
+        chat_msg = {
+            "role": "tool",
+            "name": "get_weather",
+            "content": "The weather in San Francisco is sunny, 72°F",
+        }
+
+        messages = parse_input_to_harmony_message(chat_msg)
+
+        assert len(messages) == 1
+        assert messages[0].author.role == Role.TOOL
+        assert messages[0].author.name == "functions.get_weather"
+        assert (
+            messages[0].content[0].text == "The weather in San Francisco is sunny, 72°F"
+        )
+        assert messages[0].channel == "commentary"
+
+    def test_tool_message_with_array_content(self):
+        """Test parsing tool message with array content."""
+        chat_msg = {
+            "role": "tool",
+            "name": "search_results",
+            "content": [
+                {"type": "text", "text": "Result 1: "},
+                {"type": "text", "text": "Result 2: "},
+                {
+                    "type": "image",
+                    "url": "http://example.com/img.png",
+                },  # Should be ignored
+                {"type": "text", "text": "Result 3"},
+            ],
+        }
+
+        messages = parse_input_to_harmony_message(chat_msg)
+
+        assert len(messages) == 1
+        assert messages[0].author.role == Role.TOOL
+        assert messages[0].content[0].text == "Result 1: Result 2: Result 3"
+
+    def test_tool_message_with_empty_content(self):
+        """Test parsing tool message with None content."""
+        chat_msg = {
+            "role": "tool",
+            "name": "empty_tool",
+            "content": None,
+        }
+
+        messages = parse_input_to_harmony_message(chat_msg)
+
+        assert len(messages) == 1
+        assert messages[0].content[0].text == ""
+
+    def test_system_message(self):
+        """Test parsing system message."""
+        chat_msg = {
+            "role": "system",
+            "content": "You are a helpful assistant",
+        }
+
+        messages = parse_input_to_harmony_message(chat_msg)
+
+        assert len(messages) == 1
+        # System messages are converted using Message.from_dict
+        # which should preserve the role
+        assert messages[0].author.role == Role.SYSTEM
+
+    def test_developer_message(self):
+        """Test parsing developer message."""
+        chat_msg = {
+            "role": "developer",
+            "content": "Use concise language",
+        }
+
+        messages = parse_input_to_harmony_message(chat_msg)
+
+        assert len(messages) == 1
+        assert messages[0].author.role == Role.DEVELOPER
+
+    def test_user_message_with_string_content(self):
+        """Test parsing user message with string content."""
+        chat_msg = {
+            "role": "user",
+            "content": "What's the weather in San Francisco?",
+        }
+
+        messages = parse_input_to_harmony_message(chat_msg)
+
+        assert len(messages) == 1
+        assert messages[0].author.role == Role.USER
+        assert messages[0].content[0].text == "What's the weather in San Francisco?"
+
+    def test_user_message_with_array_content(self):
+        """Test parsing user message with array content."""
+        chat_msg = {
+            "role": "user",
+            "content": [
+                {"text": "What's in this image? "},
+                {"text": "Please describe it."},
+            ],
+        }
+
+        messages = parse_input_to_harmony_message(chat_msg)
+
+        assert len(messages) == 1
+        assert messages[0].author.role == Role.USER
+        assert len(messages[0].content) == 2
+        assert messages[0].content[0].text == "What's in this image? "
+        assert messages[0].content[1].text == "Please describe it."
+
+    def test_assistant_message_with_string_content(self):
+        """Test parsing assistant message with string content (no tool calls)."""
+        chat_msg = {
+            "role": "assistant",
+            "content": "Hello! How can I help you today?",
+        }
+
+        messages = parse_input_to_harmony_message(chat_msg)
+
+        assert len(messages) == 1
+        assert messages[0].author.role == Role.ASSISTANT
+        assert messages[0].content[0].text == "Hello! How can I help you today?"
+
+    def test_pydantic_model_input(self):
+        """Test parsing Pydantic model input (has model_dump method)."""
+
+        class MockPydanticModel:
+            def model_dump(self, exclude_none=True):
+                return {
+                    "role": "user",
+                    "content": "Test message",
+                }
+
+        chat_msg = MockPydanticModel()
+        messages = parse_input_to_harmony_message(chat_msg)
+
+        assert len(messages) == 1
+        assert messages[0].author.role == Role.USER
+        assert messages[0].content[0].text == "Test message"
+
+    def test_message_with_empty_content(self):
+        """Test parsing message with empty string content."""
+        chat_msg = {
+            "role": "user",
+            "content": "",
+        }
+
+        messages = parse_input_to_harmony_message(chat_msg)
+
+        assert len(messages) == 1
+        assert messages[0].content[0].text == ""
+
+    def test_tool_call_with_missing_function_fields(self):
+        """Test parsing tool call with missing name or arguments."""
+        chat_msg = {
+            "role": "assistant",
+            "tool_calls": [
+                {
+                    "function": {}  # Missing both name and arguments
+                }
+            ],
+        }
+
+        messages = parse_input_to_harmony_message(chat_msg)
+
+        assert len(messages) == 1
+        assert messages[0].recipient == "functions."
+        assert messages[0].content[0].text == ""
+
+    def test_array_content_with_missing_text(self):
+        """Test parsing array content where text field is missing."""
+        chat_msg = {
+            "role": "user",
+            "content": [
+                {},  # Missing text field
+                {"text": "actual text"},
+            ],
+        }
+
+        messages = parse_input_to_harmony_message(chat_msg)
+
+        assert len(messages) == 1
+        assert len(messages[0].content) == 2
+        assert messages[0].content[0].text == ""
+        assert messages[0].content[1].text == "actual text"

vllm/entrypoints/harmony_utils.py

@@ -228,7 +228,7 @@ def parse_response_input(
     return msg
 
 
-def parse_chat_input(chat_msg) -> list[Message]:
+def parse_input_to_harmony_message(chat_msg) -> list[Message]:
     if not isinstance(chat_msg, dict):
         # Handle Pydantic models
         chat_msg = chat_msg.model_dump(exclude_none=True)
@@ -267,6 +267,10 @@ def parse_chat_input(chat_msg) -> list[Message]:
             Author.new(Role.TOOL, f"functions.{name}"), content
         ).with_channel("commentary")
         return [msg]
+    # system or developer message
+    if role == "system" or role == "developer":
+        msg = Message.from_dict(chat_msg)
+        return [msg]
 
     # Default: user/assistant/system messages with content
     content = chat_msg.get("content", "")