chore(responses): Refactor Responses Impl to be civilized (#3138)

# What does this PR do?
Refactors the OpenAI responses implementation by extracting streaming and tool execution logic into separate modules. This improves code organization by:

1. Creating a new `StreamingResponseOrchestrator` class in `streaming.py` to handle the streaming response generation logic
2. Moving tool execution functionality to a dedicated `ToolExecutor` class in `tool_executor.py`

## Test Plan

Existing tests

llama_stack/providers/inline/agents/meta_reference/agents.py

@@ -48,8 +48,8 @@ from llama_stack.providers.utils.responses.responses_store import ResponsesStore
 
 from .agent_instance import ChatAgent
 from .config import MetaReferenceAgentsImplConfig
-from .openai_responses import OpenAIResponsesImpl
 from .persistence import AgentInfo
+from .responses.openai_responses import OpenAIResponsesImpl
 
 logger = logging.getLogger()
 

llama_stack/providers/inline/agents/meta_reference/responses/__init__.py

@@ -0,0 +1,5 @@
+# Copyright (c) Meta Platforms, Inc. and affiliates.
+# All rights reserved.
+#
+# This source code is licensed under the terms described in the LICENSE file in
+# the root directory of this source tree.

llama_stack/providers/inline/agents/meta_reference/responses/openai_responses.py

@@ -0,0 +1,499 @@
+# Copyright (c) Meta Platforms, Inc. and affiliates.
+# All rights reserved.
+#
+# This source code is licensed under the terms described in the LICENSE file in
+# the root directory of this source tree.
+
+import time
+import uuid
+from collections.abc import AsyncIterator
+
+from openai.types.chat import ChatCompletionToolParam
+from pydantic import BaseModel
+
+from llama_stack.apis.agents import Order
+from llama_stack.apis.agents.openai_responses import (
+    AllowedToolsFilter,
+    ListOpenAIResponseInputItem,
+    ListOpenAIResponseObject,
+    MCPListToolsTool,
+    OpenAIDeleteResponseObject,
+    OpenAIResponseInput,
+    OpenAIResponseInputFunctionToolCallOutput,
+    OpenAIResponseInputMessageContent,
+    OpenAIResponseInputMessageContentImage,
+    OpenAIResponseInputMessageContentText,
+    OpenAIResponseInputTool,
+    OpenAIResponseInputToolMCP,
+    OpenAIResponseMessage,
+    OpenAIResponseObject,
+    OpenAIResponseObjectStream,
+    OpenAIResponseOutput,
+    OpenAIResponseOutputMessageContent,
+    OpenAIResponseOutputMessageContentOutputText,
+    OpenAIResponseOutputMessageFunctionToolCall,
+    OpenAIResponseOutputMessageMCPListTools,
+    OpenAIResponseText,
+    OpenAIResponseTextFormat,
+    WebSearchToolTypes,
+)
+from llama_stack.apis.inference import (
+    Inference,
+    OpenAIAssistantMessageParam,
+    OpenAIChatCompletionContentPartImageParam,
+    OpenAIChatCompletionContentPartParam,
+    OpenAIChatCompletionContentPartTextParam,
+    OpenAIChatCompletionToolCall,
+    OpenAIChatCompletionToolCallFunction,
+    OpenAIDeveloperMessageParam,
+    OpenAIImageURL,
+    OpenAIJSONSchema,
+    OpenAIMessageParam,
+    OpenAIResponseFormatJSONObject,
+    OpenAIResponseFormatJSONSchema,
+    OpenAIResponseFormatParam,
+    OpenAIResponseFormatText,
+    OpenAISystemMessageParam,
+    OpenAIToolMessageParam,
+    OpenAIUserMessageParam,
+)
+from llama_stack.apis.tools import Tool, ToolGroups, ToolRuntime
+from llama_stack.apis.vector_io import VectorIO
+from llama_stack.log import get_logger
+from llama_stack.models.llama.datatypes import ToolDefinition, ToolParamDefinition
+from llama_stack.providers.utils.inference.openai_compat import (
+    convert_tooldef_to_openai_tool,
+)
+from llama_stack.providers.utils.responses.responses_store import ResponsesStore
+
+from .streaming import StreamingResponseOrchestrator
+from .tool_executor import ToolExecutor
+from .types import ChatCompletionContext
+
+logger = get_logger(name=__name__, category="responses")
+
+
+async def _convert_response_content_to_chat_content(
+    content: (str | list[OpenAIResponseInputMessageContent] | list[OpenAIResponseOutputMessageContent]),
+) -> str | list[OpenAIChatCompletionContentPartParam]:
+    """
+    Convert the content parts from an OpenAI Response API request into OpenAI Chat Completion content parts.
+
+    The content schemas of each API look similar, but are not exactly the same.
+    """
+    if isinstance(content, str):
+        return content
+
+    converted_parts = []
+    for content_part in content:
+        if isinstance(content_part, OpenAIResponseInputMessageContentText):
+            converted_parts.append(OpenAIChatCompletionContentPartTextParam(text=content_part.text))
+        elif isinstance(content_part, OpenAIResponseOutputMessageContentOutputText):
+            converted_parts.append(OpenAIChatCompletionContentPartTextParam(text=content_part.text))
+        elif isinstance(content_part, OpenAIResponseInputMessageContentImage):
+            if content_part.image_url:
+                image_url = OpenAIImageURL(url=content_part.image_url, detail=content_part.detail)
+                converted_parts.append(OpenAIChatCompletionContentPartImageParam(image_url=image_url))
+        elif isinstance(content_part, str):
+            converted_parts.append(OpenAIChatCompletionContentPartTextParam(text=content_part))
+        else:
+            raise ValueError(
+                f"Llama Stack OpenAI Responses does not yet support content type '{type(content_part)}' in this context"
+            )
+    return converted_parts
+
+
+async def _convert_response_input_to_chat_messages(
+    input: str | list[OpenAIResponseInput],
+) -> list[OpenAIMessageParam]:
+    """
+    Convert the input from an OpenAI Response API request into OpenAI Chat Completion messages.
+    """
+    messages: list[OpenAIMessageParam] = []
+    if isinstance(input, list):
+        for input_item in input:
+            if isinstance(input_item, OpenAIResponseInputFunctionToolCallOutput):
+                messages.append(
+                    OpenAIToolMessageParam(
+                        content=input_item.output,
+                        tool_call_id=input_item.call_id,
+                    )
+                )
+            elif isinstance(input_item, OpenAIResponseOutputMessageFunctionToolCall):
+                tool_call = OpenAIChatCompletionToolCall(
+                    index=0,
+                    id=input_item.call_id,
+                    function=OpenAIChatCompletionToolCallFunction(
+                        name=input_item.name,
+                        arguments=input_item.arguments,
+                    ),
+                )
+                messages.append(OpenAIAssistantMessageParam(tool_calls=[tool_call]))
+            else:
+                content = await _convert_response_content_to_chat_content(input_item.content)
+                message_type = await _get_message_type_by_role(input_item.role)
+                if message_type is None:
+                    raise ValueError(
+                        f"Llama Stack OpenAI Responses does not yet support message role '{input_item.role}' in this context"
+                    )
+                messages.append(message_type(content=content))
+    else:
+        messages.append(OpenAIUserMessageParam(content=input))
+    return messages
+
+
+async def _convert_response_text_to_chat_response_format(
+    text: OpenAIResponseText,
+) -> OpenAIResponseFormatParam:
+    """
+    Convert an OpenAI Response text parameter into an OpenAI Chat Completion response format.
+    """
+    if not text.format or text.format["type"] == "text":
+        return OpenAIResponseFormatText(type="text")
+    if text.format["type"] == "json_object":
+        return OpenAIResponseFormatJSONObject()
+    if text.format["type"] == "json_schema":
+        return OpenAIResponseFormatJSONSchema(
+            json_schema=OpenAIJSONSchema(name=text.format["name"], schema=text.format["schema"])
+        )
+    raise ValueError(f"Unsupported text format: {text.format}")
+
+
+async def _get_message_type_by_role(role: str):
+    role_to_type = {
+        "user": OpenAIUserMessageParam,
+        "system": OpenAISystemMessageParam,
+        "assistant": OpenAIAssistantMessageParam,
+        "developer": OpenAIDeveloperMessageParam,
+    }
+    return role_to_type.get(role)
+
+
+class OpenAIResponsePreviousResponseWithInputItems(BaseModel):
+    input_items: ListOpenAIResponseInputItem
+    response: OpenAIResponseObject
+
+
+class OpenAIResponsesImpl:
+    def __init__(
+        self,
+        inference_api: Inference,
+        tool_groups_api: ToolGroups,
+        tool_runtime_api: ToolRuntime,
+        responses_store: ResponsesStore,
+        vector_io_api: VectorIO,  # VectorIO
+    ):
+        self.inference_api = inference_api
+        self.tool_groups_api = tool_groups_api
+        self.tool_runtime_api = tool_runtime_api
+        self.responses_store = responses_store
+        self.vector_io_api = vector_io_api
+        self.tool_executor = ToolExecutor(
+            tool_groups_api=tool_groups_api,
+            tool_runtime_api=tool_runtime_api,
+            vector_io_api=vector_io_api,
+        )
+
+    async def _prepend_previous_response(
+        self,
+        input: str | list[OpenAIResponseInput],
+        previous_response_id: str | None = None,
+    ):
+        if previous_response_id:
+            previous_response_with_input = await self.responses_store.get_response_object(previous_response_id)
+
+            # previous response input items
+            new_input_items = previous_response_with_input.input
+
+            # previous response output items
+            new_input_items.extend(previous_response_with_input.output)
+
+            # new input items from the current request
+            if isinstance(input, str):
+                new_input_items.append(OpenAIResponseMessage(content=input, role="user"))
+            else:
+                new_input_items.extend(input)
+
+            input = new_input_items
+
+        return input
+
+    async def _prepend_instructions(self, messages, instructions):
+        if instructions:
+            messages.insert(0, OpenAISystemMessageParam(content=instructions))
+
+    async def get_openai_response(
+        self,
+        response_id: str,
+    ) -> OpenAIResponseObject:
+        response_with_input = await self.responses_store.get_response_object(response_id)
+        return OpenAIResponseObject(**{k: v for k, v in response_with_input.model_dump().items() if k != "input"})
+
+    async def list_openai_responses(
+        self,
+        after: str | None = None,
+        limit: int | None = 50,
+        model: str | None = None,
+        order: Order | None = Order.desc,
+    ) -> ListOpenAIResponseObject:
+        return await self.responses_store.list_responses(after, limit, model, order)
+
+    async def list_openai_response_input_items(
+        self,
+        response_id: str,
+        after: str | None = None,
+        before: str | None = None,
+        include: list[str] | None = None,
+        limit: int | None = 20,
+        order: Order | None = Order.desc,
+    ) -> ListOpenAIResponseInputItem:
+        """List input items for a given OpenAI response.
+
+        :param response_id: The ID of the response to retrieve input items for.
+        :param after: An item ID to list items after, used for pagination.
+        :param before: An item ID to list items before, used for pagination.
+        :param include: Additional fields to include in the response.
+        :param limit: A limit on the number of objects to be returned.
+        :param order: The order to return the input items in.
+        :returns: An ListOpenAIResponseInputItem.
+        """
+        return await self.responses_store.list_response_input_items(response_id, after, before, include, limit, order)
+
+    async def _store_response(
+        self,
+        response: OpenAIResponseObject,
+        input: str | list[OpenAIResponseInput],
+    ) -> None:
+        new_input_id = f"msg_{uuid.uuid4()}"
+        if isinstance(input, str):
+            # synthesize a message from the input string
+            input_content = OpenAIResponseInputMessageContentText(text=input)
+            input_content_item = OpenAIResponseMessage(
+                role="user",
+                content=[input_content],
+                id=new_input_id,
+            )
+            input_items_data = [input_content_item]
+        else:
+            # we already have a list of messages
+            input_items_data = []
+            for input_item in input:
+                if isinstance(input_item, OpenAIResponseMessage):
+                    # These may or may not already have an id, so dump to dict, check for id, and add if missing
+                    input_item_dict = input_item.model_dump()
+                    if "id" not in input_item_dict:
+                        input_item_dict["id"] = new_input_id
+                    input_items_data.append(OpenAIResponseMessage(**input_item_dict))
+                else:
+                    input_items_data.append(input_item)
+
+        await self.responses_store.store_response_object(
+            response_object=response,
+            input=input_items_data,
+        )
+
+    async def create_openai_response(
+        self,
+        input: str | list[OpenAIResponseInput],
+        model: str,
+        instructions: str | None = None,
+        previous_response_id: str | None = None,
+        store: bool | None = True,
+        stream: bool | None = False,
+        temperature: float | None = None,
+        text: OpenAIResponseText | None = None,
+        tools: list[OpenAIResponseInputTool] | None = None,
+        include: list[str] | None = None,
+        max_infer_iters: int | None = 10,
+    ):
+        stream = bool(stream)
+        text = OpenAIResponseText(format=OpenAIResponseTextFormat(type="text")) if text is None else text
+
+        stream_gen = self._create_streaming_response(
+            input=input,
+            model=model,
+            instructions=instructions,
+            previous_response_id=previous_response_id,
+            store=store,
+            temperature=temperature,
+            text=text,
+            tools=tools,
+            max_infer_iters=max_infer_iters,
+        )
+
+        if stream:
+            return stream_gen
+        else:
+            response = None
+            async for stream_chunk in stream_gen:
+                if stream_chunk.type == "response.completed":
+                    if response is not None:
+                        raise ValueError("The response stream completed multiple times! Earlier response: {response}")
+                    response = stream_chunk.response
+                    # don't leave the generator half complete!
+
+            if response is None:
+                raise ValueError("The response stream never completed")
+            return response
+
+    async def _create_streaming_response(
+        self,
+        input: str | list[OpenAIResponseInput],
+        model: str,
+        instructions: str | None = None,
+        previous_response_id: str | None = None,
+        store: bool | None = True,
+        temperature: float | None = None,
+        text: OpenAIResponseText | None = None,
+        tools: list[OpenAIResponseInputTool] | None = None,
+        max_infer_iters: int | None = 10,
+    ) -> AsyncIterator[OpenAIResponseObjectStream]:
+        # Input preprocessing
+        input = await self._prepend_previous_response(input, previous_response_id)
+        messages = await _convert_response_input_to_chat_messages(input)
+        await self._prepend_instructions(messages, instructions)
+
+        # Structured outputs
+        response_format = await _convert_response_text_to_chat_response_format(text)
+
+        # Tool setup, TODO: refactor this slightly since this can also yield events
+        chat_tools, mcp_tool_to_server, mcp_list_message = (
+            await self._convert_response_tools_to_chat_tools(tools) if tools else (None, {}, None)
+        )
+
+        ctx = ChatCompletionContext(
+            model=model,
+            messages=messages,
+            response_tools=tools,
+            chat_tools=chat_tools,
+            mcp_tool_to_server=mcp_tool_to_server,
+            temperature=temperature,
+            response_format=response_format,
+        )
+
+        # Create orchestrator and delegate streaming logic
+        response_id = f"resp-{uuid.uuid4()}"
+        created_at = int(time.time())
+
+        orchestrator = StreamingResponseOrchestrator(
+            inference_api=self.inference_api,
+            ctx=ctx,
+            response_id=response_id,
+            created_at=created_at,
+            text=text,
+            max_infer_iters=max_infer_iters,
+            tool_executor=self.tool_executor,
+            mcp_list_message=mcp_list_message,
+        )
+
+        # Stream the response
+        final_response = None
+        async for stream_chunk in orchestrator.create_response():
+            if stream_chunk.type == "response.completed":
+                final_response = stream_chunk.response
+            yield stream_chunk
+
+        # Store the response if requested
+        if store and final_response:
+            await self._store_response(
+                response=final_response,
+                input=input,
+            )
+
+    async def delete_openai_response(self, response_id: str) -> OpenAIDeleteResponseObject:
+        return await self.responses_store.delete_response_object(response_id)
+
+    async def _convert_response_tools_to_chat_tools(
+        self, tools: list[OpenAIResponseInputTool]
+    ) -> tuple[
+        list[ChatCompletionToolParam],
+        dict[str, OpenAIResponseInputToolMCP],
+        OpenAIResponseOutput | None,
+    ]:
+        mcp_tool_to_server = {}
+
+        def make_openai_tool(tool_name: str, tool: Tool) -> ChatCompletionToolParam:
+            tool_def = ToolDefinition(
+                tool_name=tool_name,
+                description=tool.description,
+                parameters={
+                    param.name: ToolParamDefinition(
+                        param_type=param.parameter_type,
+                        description=param.description,
+                        required=param.required,
+                        default=param.default,
+                    )
+                    for param in tool.parameters
+                },
+            )
+            return convert_tooldef_to_openai_tool(tool_def)
+
+        mcp_list_message = None
+        chat_tools: list[ChatCompletionToolParam] = []
+        for input_tool in tools:
+            # TODO: Handle other tool types
+            if input_tool.type == "function":
+                chat_tools.append(ChatCompletionToolParam(type="function", function=input_tool.model_dump()))
+            elif input_tool.type in WebSearchToolTypes:
+                tool_name = "web_search"
+                tool = await self.tool_groups_api.get_tool(tool_name)
+                if not tool:
+                    raise ValueError(f"Tool {tool_name} not found")
+                chat_tools.append(make_openai_tool(tool_name, tool))
+            elif input_tool.type == "file_search":
+                tool_name = "knowledge_search"
+                tool = await self.tool_groups_api.get_tool(tool_name)
+                if not tool:
+                    raise ValueError(f"Tool {tool_name} not found")
+                chat_tools.append(make_openai_tool(tool_name, tool))
+            elif input_tool.type == "mcp":
+                from llama_stack.providers.utils.tools.mcp import list_mcp_tools
+
+                always_allowed = None
+                never_allowed = None
+                if input_tool.allowed_tools:
+                    if isinstance(input_tool.allowed_tools, list):
+                        always_allowed = input_tool.allowed_tools
+                    elif isinstance(input_tool.allowed_tools, AllowedToolsFilter):
+                        always_allowed = input_tool.allowed_tools.always
+                        never_allowed = input_tool.allowed_tools.never
+
+                tool_defs = await list_mcp_tools(
+                    endpoint=input_tool.server_url,
+                    headers=input_tool.headers or {},
+                )
+
+                mcp_list_message = OpenAIResponseOutputMessageMCPListTools(
+                    id=f"mcp_list_{uuid.uuid4()}",
+                    status="completed",
+                    server_label=input_tool.server_label,
+                    tools=[],
+                )
+                for t in tool_defs.data:
+                    if never_allowed and t.name in never_allowed:
+                        continue
+                    if not always_allowed or t.name in always_allowed:
+                        chat_tools.append(make_openai_tool(t.name, t))
+                        if t.name in mcp_tool_to_server:
+                            raise ValueError(f"Duplicate tool name {t.name} found for server {input_tool.server_label}")
+                        mcp_tool_to_server[t.name] = input_tool
+                        mcp_list_message.tools.append(
+                            MCPListToolsTool(
+                                name=t.name,
+                                description=t.description,
+                                input_schema={
+                                    "type": "object",
+                                    "properties": {
+                                        p.name: {
+                                            "type": p.parameter_type,
+                                            "description": p.description,
+                                        }
+                                        for p in t.parameters
+                                    },
+                                    "required": [p.name for p in t.parameters if p.required],
+                                },
+                            )
+                        )
+            else:
+                raise ValueError(f"Llama Stack OpenAI Responses does not yet support tool type: {input_tool.type}")
+        return chat_tools, mcp_tool_to_server, mcp_list_message

llama_stack/providers/inline/agents/meta_reference/responses/streaming.py

@@ -0,0 +1,451 @@
+# Copyright (c) Meta Platforms, Inc. and affiliates.
+# All rights reserved.
+#
+# This source code is licensed under the terms described in the LICENSE file in
+# the root directory of this source tree.
+
+import uuid
+from collections.abc import AsyncIterator
+from typing import Any
+
+from llama_stack.apis.agents.openai_responses import (
+    OpenAIResponseContentPartOutputText,
+    OpenAIResponseObject,
+    OpenAIResponseObjectStream,
+    OpenAIResponseObjectStreamResponseCompleted,
+    OpenAIResponseObjectStreamResponseContentPartAdded,
+    OpenAIResponseObjectStreamResponseContentPartDone,
+    OpenAIResponseObjectStreamResponseCreated,
+    OpenAIResponseObjectStreamResponseFunctionCallArgumentsDelta,
+    OpenAIResponseObjectStreamResponseFunctionCallArgumentsDone,
+    OpenAIResponseObjectStreamResponseMcpCallArgumentsDelta,
+    OpenAIResponseObjectStreamResponseMcpCallArgumentsDone,
+    OpenAIResponseObjectStreamResponseOutputItemAdded,
+    OpenAIResponseObjectStreamResponseOutputItemDone,
+    OpenAIResponseObjectStreamResponseOutputTextDelta,
+    OpenAIResponseOutput,
+    OpenAIResponseOutputMessageFunctionToolCall,
+    OpenAIResponseText,
+)
+from llama_stack.apis.inference import (
+    Inference,
+    OpenAIAssistantMessageParam,
+    OpenAIChatCompletion,
+    OpenAIChatCompletionToolCall,
+    OpenAIChoice,
+)
+from llama_stack.log import get_logger
+
+from .types import ChatCompletionContext, ChatCompletionResult
+from .utils import convert_chat_choice_to_response_message, is_function_tool_call
+
+logger = get_logger(name=__name__, category="responses")
+
+
+class StreamingResponseOrchestrator:
+    def __init__(
+        self,
+        inference_api: Inference,
+        ctx: ChatCompletionContext,
+        response_id: str,
+        created_at: int,
+        text: OpenAIResponseText,
+        max_infer_iters: int,
+        tool_executor,  # Will be the tool execution logic from the main class
+        mcp_list_message: OpenAIResponseOutput | None = None,
+    ):
+        self.inference_api = inference_api
+        self.ctx = ctx
+        self.response_id = response_id
+        self.created_at = created_at
+        self.text = text
+        self.max_infer_iters = max_infer_iters
+        self.tool_executor = tool_executor
+        self.sequence_number = 0
+        self.mcp_list_message = mcp_list_message
+
+    async def create_response(self) -> AsyncIterator[OpenAIResponseObjectStream]:
+        # Initialize output messages with MCP list message if present
+        output_messages: list[OpenAIResponseOutput] = []
+        if self.mcp_list_message:
+            output_messages.append(self.mcp_list_message)
+        # Create initial response and emit response.created immediately
+        initial_response = OpenAIResponseObject(
+            created_at=self.created_at,
+            id=self.response_id,
+            model=self.ctx.model,
+            object="response",
+            status="in_progress",
+            output=output_messages.copy(),
+            text=self.text,
+        )
+
+        yield OpenAIResponseObjectStreamResponseCreated(response=initial_response)
+
+        n_iter = 0
+        messages = self.ctx.messages.copy()
+
+        while True:
+            completion_result = await self.inference_api.openai_chat_completion(
+                model=self.ctx.model,
+                messages=messages,
+                tools=self.ctx.chat_tools,
+                stream=True,
+                temperature=self.ctx.temperature,
+                response_format=self.ctx.response_format,
+            )
+
+            # Process streaming chunks and build complete response
+            completion_result_data = None
+            async for stream_event_or_result in self._process_streaming_chunks(completion_result, output_messages):
+                if isinstance(stream_event_or_result, ChatCompletionResult):
+                    completion_result_data = stream_event_or_result
+                else:
+                    yield stream_event_or_result
+            if not completion_result_data:
+                raise ValueError("Streaming chunk processor failed to return completion data")
+            current_response = self._build_chat_completion(completion_result_data)
+
+            function_tool_calls, non_function_tool_calls, next_turn_messages = self._separate_tool_calls(
+                current_response, messages
+            )
+
+            # Handle choices with no tool calls
+            for choice in current_response.choices:
+                if not (choice.message.tool_calls and self.ctx.response_tools):
+                    output_messages.append(await convert_chat_choice_to_response_message(choice))
+
+            # Execute tool calls and coordinate results
+            async for stream_event in self._coordinate_tool_execution(
+                function_tool_calls,
+                non_function_tool_calls,
+                completion_result_data,
+                output_messages,
+                next_turn_messages,
+            ):
+                yield stream_event
+
+            if not function_tool_calls and not non_function_tool_calls:
+                break
+
+            if function_tool_calls:
+                logger.info("Exiting inference loop since there is a function (client-side) tool call")
+                break
+
+            n_iter += 1
+            if n_iter >= self.max_infer_iters:
+                logger.info(f"Exiting inference loop since iteration count({n_iter}) exceeds {self.max_infer_iters=}")
+                break
+
+            messages = next_turn_messages
+
+        # Create final response
+        final_response = OpenAIResponseObject(
+            created_at=self.created_at,
+            id=self.response_id,
+            model=self.ctx.model,
+            object="response",
+            status="completed",
+            text=self.text,
+            output=output_messages,
+        )
+
+        # Emit response.completed
+        yield OpenAIResponseObjectStreamResponseCompleted(response=final_response)
+
+    def _separate_tool_calls(self, current_response, messages) -> tuple[list, list, list]:
+        """Separate tool calls into function and non-function categories."""
+        function_tool_calls = []
+        non_function_tool_calls = []
+        next_turn_messages = messages.copy()
+
+        for choice in current_response.choices:
+            next_turn_messages.append(choice.message)
+
+            if choice.message.tool_calls and self.ctx.response_tools:
+                for tool_call in choice.message.tool_calls:
+                    if is_function_tool_call(tool_call, self.ctx.response_tools):
+                        function_tool_calls.append(tool_call)
+                    else:
+                        non_function_tool_calls.append(tool_call)
+
+        return function_tool_calls, non_function_tool_calls, next_turn_messages
+
+    async def _process_streaming_chunks(
+        self, completion_result, output_messages: list[OpenAIResponseOutput]
+    ) -> AsyncIterator[OpenAIResponseObjectStream | ChatCompletionResult]:
+        """Process streaming chunks and emit events, returning completion data."""
+        # Initialize result tracking
+        chat_response_id = ""
+        chat_response_content = []
+        chat_response_tool_calls: dict[int, OpenAIChatCompletionToolCall] = {}
+        chunk_created = 0
+        chunk_model = ""
+        chunk_finish_reason = ""
+
+        # Create a placeholder message item for delta events
+        message_item_id = f"msg_{uuid.uuid4()}"
+        # Track tool call items for streaming events
+        tool_call_item_ids: dict[int, str] = {}
+        # Track content parts for streaming events
+        content_part_emitted = False
+
+        async for chunk in completion_result:
+            chat_response_id = chunk.id
+            chunk_created = chunk.created
+            chunk_model = chunk.model
+            for chunk_choice in chunk.choices:
+                # Emit incremental text content as delta events
+                if chunk_choice.delta.content:
+                    # Emit content_part.added event for first text chunk
+                    if not content_part_emitted:
+                        content_part_emitted = True
+                        self.sequence_number += 1
+                        yield OpenAIResponseObjectStreamResponseContentPartAdded(
+                            response_id=self.response_id,
+                            item_id=message_item_id,
+                            part=OpenAIResponseContentPartOutputText(
+                                text="",  # Will be filled incrementally via text deltas
+                            ),
+                            sequence_number=self.sequence_number,
+                        )
+                    self.sequence_number += 1
+                    yield OpenAIResponseObjectStreamResponseOutputTextDelta(
+                        content_index=0,
+                        delta=chunk_choice.delta.content,
+                        item_id=message_item_id,
+                        output_index=0,
+                        sequence_number=self.sequence_number,
+                    )
+
+                # Collect content for final response
+                chat_response_content.append(chunk_choice.delta.content or "")
+                if chunk_choice.finish_reason:
+                    chunk_finish_reason = chunk_choice.finish_reason
+
+                # Aggregate tool call arguments across chunks
+                if chunk_choice.delta.tool_calls:
+                    for tool_call in chunk_choice.delta.tool_calls:
+                        response_tool_call = chat_response_tool_calls.get(tool_call.index, None)
+                        # Create new tool call entry if this is the first chunk for this index
+                        is_new_tool_call = response_tool_call is None
+                        if is_new_tool_call:
+                            tool_call_dict: dict[str, Any] = tool_call.model_dump()
+                            tool_call_dict.pop("type", None)
+                            response_tool_call = OpenAIChatCompletionToolCall(**tool_call_dict)
+                            chat_response_tool_calls[tool_call.index] = response_tool_call
+
+                            # Create item ID for this tool call for streaming events
+                            tool_call_item_id = f"fc_{uuid.uuid4()}"
+                            tool_call_item_ids[tool_call.index] = tool_call_item_id
+
+                            # Emit output_item.added event for the new function call
+                            self.sequence_number += 1
+                            function_call_item = OpenAIResponseOutputMessageFunctionToolCall(
+                                arguments="",  # Will be filled incrementally via delta events
+                                call_id=tool_call.id or "",
+                                name=tool_call.function.name if tool_call.function else "",
+                                id=tool_call_item_id,
+                                status="in_progress",
+                            )
+                            yield OpenAIResponseObjectStreamResponseOutputItemAdded(
+                                response_id=self.response_id,
+                                item=function_call_item,
+                                output_index=len(output_messages),
+                                sequence_number=self.sequence_number,
+                            )
+
+                        # Stream tool call arguments as they arrive (differentiate between MCP and function calls)
+                        if tool_call.function and tool_call.function.arguments:
+                            tool_call_item_id = tool_call_item_ids[tool_call.index]
+                            self.sequence_number += 1
+
+                            # Check if this is an MCP tool call
+                            is_mcp_tool = (
+                                tool_call.function.name and tool_call.function.name in self.ctx.mcp_tool_to_server
+                            )
+                            if is_mcp_tool:
+                                # Emit MCP-specific argument delta event
+                                yield OpenAIResponseObjectStreamResponseMcpCallArgumentsDelta(
+                                    delta=tool_call.function.arguments,
+                                    item_id=tool_call_item_id,
+                                    output_index=len(output_messages),
+                                    sequence_number=self.sequence_number,
+                                )
+                            else:
+                                # Emit function call argument delta event
+                                yield OpenAIResponseObjectStreamResponseFunctionCallArgumentsDelta(
+                                    delta=tool_call.function.arguments,
+                                    item_id=tool_call_item_id,
+                                    output_index=len(output_messages),
+                                    sequence_number=self.sequence_number,
+                                )
+
+                            # Accumulate arguments for final response (only for subsequent chunks)
+                            if not is_new_tool_call:
+                                response_tool_call.function.arguments = (
+                                    response_tool_call.function.arguments or ""
+                                ) + tool_call.function.arguments
+
+        # Emit arguments.done events for completed tool calls (differentiate between MCP and function calls)
+        for tool_call_index in sorted(chat_response_tool_calls.keys()):
+            tool_call_item_id = tool_call_item_ids[tool_call_index]
+            final_arguments = chat_response_tool_calls[tool_call_index].function.arguments or ""
+            tool_call_name = chat_response_tool_calls[tool_call_index].function.name
+
+            # Check if this is an MCP tool call
+            is_mcp_tool = (
+                self.ctx.mcp_tool_to_server and tool_call_name and tool_call_name in self.ctx.mcp_tool_to_server
+            )
+            self.sequence_number += 1
+            done_event_cls = (
+                OpenAIResponseObjectStreamResponseMcpCallArgumentsDone
+                if is_mcp_tool
+                else OpenAIResponseObjectStreamResponseFunctionCallArgumentsDone
+            )
+            yield done_event_cls(
+                arguments=final_arguments,
+                item_id=tool_call_item_id,
+                output_index=len(output_messages),
+                sequence_number=self.sequence_number,
+            )
+
+        # Emit content_part.done event if text content was streamed (before content gets cleared)
+        if content_part_emitted:
+            final_text = "".join(chat_response_content)
+            self.sequence_number += 1
+            yield OpenAIResponseObjectStreamResponseContentPartDone(
+                response_id=self.response_id,
+                item_id=message_item_id,
+                part=OpenAIResponseContentPartOutputText(
+                    text=final_text,
+                ),
+                sequence_number=self.sequence_number,
+            )
+
+        # Clear content when there are tool calls (OpenAI spec behavior)
+        if chat_response_tool_calls:
+            chat_response_content = []
+
+        yield ChatCompletionResult(
+            response_id=chat_response_id,
+            content=chat_response_content,
+            tool_calls=chat_response_tool_calls,
+            created=chunk_created,
+            model=chunk_model,
+            finish_reason=chunk_finish_reason,
+            message_item_id=message_item_id,
+            tool_call_item_ids=tool_call_item_ids,
+            content_part_emitted=content_part_emitted,
+        )
+
+    def _build_chat_completion(self, result: ChatCompletionResult) -> OpenAIChatCompletion:
+        """Build OpenAIChatCompletion from ChatCompletionResult."""
+        # Convert collected chunks to complete response
+        if result.tool_calls:
+            tool_calls = [result.tool_calls[i] for i in sorted(result.tool_calls.keys())]
+        else:
+            tool_calls = None
+
+        assistant_message = OpenAIAssistantMessageParam(
+            content=result.content_text,
+            tool_calls=tool_calls,
+        )
+        return OpenAIChatCompletion(
+            id=result.response_id,
+            choices=[
+                OpenAIChoice(
+                    message=assistant_message,
+                    finish_reason=result.finish_reason,
+                    index=0,
+                )
+            ],
+            created=result.created,
+            model=result.model,
+        )
+
+    async def _coordinate_tool_execution(
+        self,
+        function_tool_calls: list,
+        non_function_tool_calls: list,
+        completion_result_data: ChatCompletionResult,
+        output_messages: list[OpenAIResponseOutput],
+        next_turn_messages: list,
+    ) -> AsyncIterator[OpenAIResponseObjectStream]:
+        """Coordinate execution of both function and non-function tool calls."""
+        # Execute non-function tool calls
+        for tool_call in non_function_tool_calls:
+            # Find the item_id for this tool call
+            matching_item_id = None
+            for index, item_id in completion_result_data.tool_call_item_ids.items():
+                response_tool_call = completion_result_data.tool_calls.get(index)
+                if response_tool_call and response_tool_call.id == tool_call.id:
+                    matching_item_id = item_id
+                    break
+
+            # Use a fallback item_id if not found
+            if not matching_item_id:
+                matching_item_id = f"tc_{uuid.uuid4()}"
+
+            # Execute tool call with streaming
+            tool_call_log = None
+            tool_response_message = None
+            async for result in self.tool_executor.execute_tool_call(
+                tool_call, self.ctx, self.sequence_number, len(output_messages), matching_item_id
+            ):
+                if result.stream_event:
+                    # Forward streaming events
+                    self.sequence_number = result.sequence_number
+                    yield result.stream_event
+
+                if result.final_output_message is not None:
+                    tool_call_log = result.final_output_message
+                    tool_response_message = result.final_input_message
+                    self.sequence_number = result.sequence_number
+
+            if tool_call_log:
+                output_messages.append(tool_call_log)
+
+                # Emit output_item.done event for completed non-function tool call
+                if matching_item_id:
+                    self.sequence_number += 1
+                    yield OpenAIResponseObjectStreamResponseOutputItemDone(
+                        response_id=self.response_id,
+                        item=tool_call_log,
+                        output_index=len(output_messages) - 1,
+                        sequence_number=self.sequence_number,
+                    )
+
+            if tool_response_message:
+                next_turn_messages.append(tool_response_message)
+
+        # Execute function tool calls (client-side)
+        for tool_call in function_tool_calls:
+            # Find the item_id for this tool call from our tracking dictionary
+            matching_item_id = None
+            for index, item_id in completion_result_data.tool_call_item_ids.items():
+                response_tool_call = completion_result_data.tool_calls.get(index)
+                if response_tool_call and response_tool_call.id == tool_call.id:
+                    matching_item_id = item_id
+                    break
+
+            # Use existing item_id or create new one if not found
+            final_item_id = matching_item_id or f"fc_{uuid.uuid4()}"
+
+            function_call_item = OpenAIResponseOutputMessageFunctionToolCall(
+                arguments=tool_call.function.arguments or "",
+                call_id=tool_call.id,
+                name=tool_call.function.name or "",
+                id=final_item_id,
+                status="completed",
+            )
+            output_messages.append(function_call_item)
+
+            # Emit output_item.done event for completed function call
+            self.sequence_number += 1
+            yield OpenAIResponseObjectStreamResponseOutputItemDone(
+                response_id=self.response_id,
+                item=function_call_item,
+                output_index=len(output_messages) - 1,
+                sequence_number=self.sequence_number,
+            )

llama_stack/providers/inline/agents/meta_reference/responses/tool_executor.py

@@ -0,0 +1,365 @@
+# Copyright (c) Meta Platforms, Inc. and affiliates.
+# All rights reserved.
+#
+# This source code is licensed under the terms described in the LICENSE file in
+# the root directory of this source tree.
+
+import asyncio
+import json
+from collections.abc import AsyncIterator
+
+from llama_stack.apis.agents.openai_responses import (
+    OpenAIResponseInputToolFileSearch,
+    OpenAIResponseObjectStreamResponseMcpCallCompleted,
+    OpenAIResponseObjectStreamResponseMcpCallFailed,
+    OpenAIResponseObjectStreamResponseMcpCallInProgress,
+    OpenAIResponseObjectStreamResponseWebSearchCallCompleted,
+    OpenAIResponseObjectStreamResponseWebSearchCallInProgress,
+    OpenAIResponseObjectStreamResponseWebSearchCallSearching,
+    OpenAIResponseOutputMessageFileSearchToolCall,
+    OpenAIResponseOutputMessageFileSearchToolCallResults,
+    OpenAIResponseOutputMessageWebSearchToolCall,
+)
+from llama_stack.apis.common.content_types import (
+    ImageContentItem,
+    TextContentItem,
+)
+from llama_stack.apis.inference import (
+    OpenAIChatCompletionContentPartImageParam,
+    OpenAIChatCompletionContentPartTextParam,
+    OpenAIChatCompletionToolCall,
+    OpenAIImageURL,
+    OpenAIToolMessageParam,
+)
+from llama_stack.apis.tools import ToolGroups, ToolInvocationResult, ToolRuntime
+from llama_stack.apis.vector_io import VectorIO
+from llama_stack.log import get_logger
+
+from .types import ChatCompletionContext, ToolExecutionResult
+
+logger = get_logger(name=__name__, category="responses")
+
+
+class ToolExecutor:
+    def __init__(
+        self,
+        tool_groups_api: ToolGroups,
+        tool_runtime_api: ToolRuntime,
+        vector_io_api: VectorIO,
+    ):
+        self.tool_groups_api = tool_groups_api
+        self.tool_runtime_api = tool_runtime_api
+        self.vector_io_api = vector_io_api
+
+    async def execute_tool_call(
+        self,
+        tool_call: OpenAIChatCompletionToolCall,
+        ctx: ChatCompletionContext,
+        sequence_number: int,
+        output_index: int,
+        item_id: str,
+    ) -> AsyncIterator[ToolExecutionResult]:
+        tool_call_id = tool_call.id
+        function = tool_call.function
+        tool_kwargs = json.loads(function.arguments) if function.arguments else {}
+
+        if not function or not tool_call_id or not function.name:
+            yield ToolExecutionResult(sequence_number=sequence_number)
+            return
+
+        # Emit progress events for tool execution start
+        async for event_result in self._emit_progress_events(
+            function.name, ctx, sequence_number, output_index, item_id
+        ):
+            sequence_number = event_result.sequence_number
+            yield event_result
+
+        # Execute the actual tool call
+        error_exc, result = await self._execute_tool(function.name, tool_kwargs, ctx)
+
+        # Emit completion events for tool execution
+        has_error = error_exc or (result and ((result.error_code and result.error_code > 0) or result.error_message))
+        async for event_result in self._emit_completion_events(
+            function.name, ctx, sequence_number, output_index, item_id, has_error
+        ):
+            sequence_number = event_result.sequence_number
+            yield event_result
+
+        # Build result messages from tool execution
+        output_message, input_message = await self._build_result_messages(
+            function, tool_call_id, tool_kwargs, ctx, error_exc, result, has_error
+        )
+
+        # Yield the final result
+        yield ToolExecutionResult(
+            sequence_number=sequence_number, final_output_message=output_message, final_input_message=input_message
+        )
+
+    async def _execute_knowledge_search_via_vector_store(
+        self,
+        query: str,
+        response_file_search_tool: OpenAIResponseInputToolFileSearch,
+    ) -> ToolInvocationResult:
+        """Execute knowledge search using vector_stores.search API with filters support."""
+        search_results = []
+
+        # Create search tasks for all vector stores
+        async def search_single_store(vector_store_id):
+            try:
+                search_response = await self.vector_io_api.openai_search_vector_store(
+                    vector_store_id=vector_store_id,
+                    query=query,
+                    filters=response_file_search_tool.filters,
+                    max_num_results=response_file_search_tool.max_num_results,
+                    ranking_options=response_file_search_tool.ranking_options,
+                    rewrite_query=False,
+                )
+                return search_response.data
+            except Exception as e:
+                logger.warning(f"Failed to search vector store {vector_store_id}: {e}")
+                return []
+
+        # Run all searches in parallel using gather
+        search_tasks = [search_single_store(vid) for vid in response_file_search_tool.vector_store_ids]
+        all_results = await asyncio.gather(*search_tasks)
+
+        # Flatten results
+        for results in all_results:
+            search_results.extend(results)
+
+        # Convert search results to tool result format matching memory.py
+        # Format the results as interleaved content similar to memory.py
+        content_items = []
+        content_items.append(
+            TextContentItem(
+                text=f"knowledge_search tool found {len(search_results)} chunks:\nBEGIN of knowledge_search tool results.\n"
+            )
+        )
+
+        for i, result_item in enumerate(search_results):
+            chunk_text = result_item.content[0].text if result_item.content else ""
+            metadata_text = f"document_id: {result_item.file_id}, score: {result_item.score}"
+            if result_item.attributes:
+                metadata_text += f", attributes: {result_item.attributes}"
+            text_content = f"[{i + 1}] {metadata_text}\n{chunk_text}\n"
+            content_items.append(TextContentItem(text=text_content))
+
+        content_items.append(TextContentItem(text="END of knowledge_search tool results.\n"))
+        content_items.append(
+            TextContentItem(
+                text=f'The above results were retrieved to help answer the user\'s query: "{query}". Use them as supporting information only in answering this query.\n',
+            )
+        )
+
+        return ToolInvocationResult(
+            content=content_items,
+            metadata={
+                "document_ids": [r.file_id for r in search_results],
+                "chunks": [r.content[0].text if r.content else "" for r in search_results],
+                "scores": [r.score for r in search_results],
+            },
+        )
+
+    async def _emit_progress_events(
+        self, function_name: str, ctx: ChatCompletionContext, sequence_number: int, output_index: int, item_id: str
+    ) -> AsyncIterator[ToolExecutionResult]:
+        """Emit progress events for tool execution start."""
+        # Emit in_progress event based on tool type (only for tools with specific streaming events)
+        progress_event = None
+        if ctx.mcp_tool_to_server and function_name in ctx.mcp_tool_to_server:
+            sequence_number += 1
+            progress_event = OpenAIResponseObjectStreamResponseMcpCallInProgress(
+                item_id=item_id,
+                output_index=output_index,
+                sequence_number=sequence_number,
+            )
+        elif function_name == "web_search":
+            sequence_number += 1
+            progress_event = OpenAIResponseObjectStreamResponseWebSearchCallInProgress(
+                item_id=item_id,
+                output_index=output_index,
+                sequence_number=sequence_number,
+            )
+        # Note: knowledge_search and other custom tools don't have specific streaming events in OpenAI spec
+
+        if progress_event:
+            yield ToolExecutionResult(stream_event=progress_event, sequence_number=sequence_number)
+
+        # For web search, emit searching event
+        if function_name == "web_search":
+            sequence_number += 1
+            searching_event = OpenAIResponseObjectStreamResponseWebSearchCallSearching(
+                item_id=item_id,
+                output_index=output_index,
+                sequence_number=sequence_number,
+            )
+            yield ToolExecutionResult(stream_event=searching_event, sequence_number=sequence_number)
+
+    async def _execute_tool(
+        self, function_name: str, tool_kwargs: dict, ctx: ChatCompletionContext
+    ) -> tuple[Exception | None, any]:
+        """Execute the tool and return error exception and result."""
+        error_exc = None
+        result = None
+
+        try:
+            if ctx.mcp_tool_to_server and function_name in ctx.mcp_tool_to_server:
+                from llama_stack.providers.utils.tools.mcp import invoke_mcp_tool
+
+                mcp_tool = ctx.mcp_tool_to_server[function_name]
+                result = await invoke_mcp_tool(
+                    endpoint=mcp_tool.server_url,
+                    headers=mcp_tool.headers or {},
+                    tool_name=function_name,
+                    kwargs=tool_kwargs,
+                )
+            elif function_name == "knowledge_search":
+                response_file_search_tool = next(
+                    (t for t in ctx.response_tools if isinstance(t, OpenAIResponseInputToolFileSearch)),
+                    None,
+                )
+                if response_file_search_tool:
+                    # Use vector_stores.search API instead of knowledge_search tool
+                    # to support filters and ranking_options
+                    query = tool_kwargs.get("query", "")
+                    result = await self._execute_knowledge_search_via_vector_store(
+                        query=query,
+                        response_file_search_tool=response_file_search_tool,
+                    )
+            else:
+                result = await self.tool_runtime_api.invoke_tool(
+                    tool_name=function_name,
+                    kwargs=tool_kwargs,
+                )
+        except Exception as e:
+            error_exc = e
+
+        return error_exc, result
+
+    async def _emit_completion_events(
+        self,
+        function_name: str,
+        ctx: ChatCompletionContext,
+        sequence_number: int,
+        output_index: int,
+        item_id: str,
+        has_error: bool,
+    ) -> AsyncIterator[ToolExecutionResult]:
+        """Emit completion or failure events for tool execution."""
+        completion_event = None
+
+        if ctx.mcp_tool_to_server and function_name in ctx.mcp_tool_to_server:
+            sequence_number += 1
+            if has_error:
+                completion_event = OpenAIResponseObjectStreamResponseMcpCallFailed(
+                    sequence_number=sequence_number,
+                )
+            else:
+                completion_event = OpenAIResponseObjectStreamResponseMcpCallCompleted(
+                    sequence_number=sequence_number,
+                )
+        elif function_name == "web_search":
+            sequence_number += 1
+            completion_event = OpenAIResponseObjectStreamResponseWebSearchCallCompleted(
+                item_id=item_id,
+                output_index=output_index,
+                sequence_number=sequence_number,
+            )
+        # Note: knowledge_search and other custom tools don't have specific completion events in OpenAI spec
+
+        if completion_event:
+            yield ToolExecutionResult(stream_event=completion_event, sequence_number=sequence_number)
+
+    async def _build_result_messages(
+        self,
+        function,
+        tool_call_id: str,
+        tool_kwargs: dict,
+        ctx: ChatCompletionContext,
+        error_exc: Exception | None,
+        result: any,
+        has_error: bool,
+    ) -> tuple[any, any]:
+        """Build output and input messages from tool execution results."""
+        from llama_stack.providers.utils.inference.prompt_adapter import (
+            interleaved_content_as_str,
+        )
+
+        # Build output message
+        if function.name in ctx.mcp_tool_to_server:
+            from llama_stack.apis.agents.openai_responses import (
+                OpenAIResponseOutputMessageMCPCall,
+            )
+
+            message = OpenAIResponseOutputMessageMCPCall(
+                id=tool_call_id,
+                arguments=function.arguments,
+                name=function.name,
+                server_label=ctx.mcp_tool_to_server[function.name].server_label,
+            )
+            if error_exc:
+                message.error = str(error_exc)
+            elif (result and result.error_code and result.error_code > 0) or (result and result.error_message):
+                message.error = f"Error (code {result.error_code}): {result.error_message}"
+            elif result and result.content:
+                message.output = interleaved_content_as_str(result.content)
+        else:
+            if function.name == "web_search":
+                message = OpenAIResponseOutputMessageWebSearchToolCall(
+                    id=tool_call_id,
+                    status="completed",
+                )
+                if has_error:
+                    message.status = "failed"
+            elif function.name == "knowledge_search":
+                message = OpenAIResponseOutputMessageFileSearchToolCall(
+                    id=tool_call_id,
+                    queries=[tool_kwargs.get("query", "")],
+                    status="completed",
+                )
+                if result and "document_ids" in result.metadata:
+                    message.results = []
+                    for i, doc_id in enumerate(result.metadata["document_ids"]):
+                        text = result.metadata["chunks"][i] if "chunks" in result.metadata else None
+                        score = result.metadata["scores"][i] if "scores" in result.metadata else None
+                        message.results.append(
+                            OpenAIResponseOutputMessageFileSearchToolCallResults(
+                                file_id=doc_id,
+                                filename=doc_id,
+                                text=text,
+                                score=score,
+                                attributes={},
+                            )
+                        )
+                if has_error:
+                    message.status = "failed"
+            else:
+                raise ValueError(f"Unknown tool {function.name} called")
+
+        # Build input message
+        input_message = None
+        if result and result.content:
+            if isinstance(result.content, str):
+                content = result.content
+            elif isinstance(result.content, list):
+                content = []
+                for item in result.content:
+                    if isinstance(item, TextContentItem):
+                        part = OpenAIChatCompletionContentPartTextParam(text=item.text)
+                    elif isinstance(item, ImageContentItem):
+                        if item.image.data:
+                            url = f"data:image;base64,{item.image.data}"
+                        else:
+                            url = item.image.url
+                        part = OpenAIChatCompletionContentPartImageParam(image_url=OpenAIImageURL(url=url))
+                    else:
+                        raise ValueError(f"Unknown result content type: {type(item)}")
+                    content.append(part)
+            else:
+                raise ValueError(f"Unknown result content type: {type(result.content)}")
+            input_message = OpenAIToolMessageParam(content=content, tool_call_id=tool_call_id)
+        else:
+            text = str(error_exc) if error_exc else "Tool execution failed"
+            input_message = OpenAIToolMessageParam(content=text, tool_call_id=tool_call_id)
+
+        return message, input_message

llama_stack/providers/inline/agents/meta_reference/responses/types.py

@@ -0,0 +1,62 @@
+# Copyright (c) Meta Platforms, Inc. and affiliates.
+# All rights reserved.
+#
+# This source code is licensed under the terms described in the LICENSE file in
+# the root directory of this source tree.
+
+from dataclasses import dataclass
+
+from openai.types.chat import ChatCompletionToolParam
+from pydantic import BaseModel
+
+from llama_stack.apis.agents.openai_responses import (
+    OpenAIResponseInputTool,
+    OpenAIResponseInputToolMCP,
+    OpenAIResponseObjectStream,
+    OpenAIResponseOutput,
+)
+from llama_stack.apis.inference import OpenAIChatCompletionToolCall, OpenAIMessageParam, OpenAIResponseFormatParam
+
+
+class ToolExecutionResult(BaseModel):
+    """Result of streaming tool execution."""
+
+    stream_event: OpenAIResponseObjectStream | None = None
+    sequence_number: int
+    final_output_message: OpenAIResponseOutput | None = None
+    final_input_message: OpenAIMessageParam | None = None
+
+
+@dataclass
+class ChatCompletionResult:
+    """Result of processing streaming chat completion chunks."""
+
+    response_id: str
+    content: list[str]
+    tool_calls: dict[int, OpenAIChatCompletionToolCall]
+    created: int
+    model: str
+    finish_reason: str
+    message_item_id: str  # For streaming events
+    tool_call_item_ids: dict[int, str]  # For streaming events
+    content_part_emitted: bool  # Tracking state
+
+    @property
+    def content_text(self) -> str:
+        """Get joined content as string."""
+        return "".join(self.content)
+
+    @property
+    def has_tool_calls(self) -> bool:
+        """Check if there are any tool calls."""
+        return bool(self.tool_calls)
+
+
+class ChatCompletionContext(BaseModel):
+    model: str
+    messages: list[OpenAIMessageParam]
+    response_tools: list[OpenAIResponseInputTool] | None = None
+    chat_tools: list[ChatCompletionToolParam] | None = None
+    mcp_tool_to_server: dict[str, OpenAIResponseInputToolMCP]
+    temperature: float | None
+    response_format: OpenAIResponseFormatParam

llama_stack/providers/inline/agents/meta_reference/responses/utils.py

@@ -0,0 +1,50 @@
+# Copyright (c) Meta Platforms, Inc. and affiliates.
+# All rights reserved.
+#
+# This source code is licensed under the terms described in the LICENSE file in
+# the root directory of this source tree.
+
+import uuid
+
+from llama_stack.apis.agents.openai_responses import (
+    OpenAIResponseInputTool,
+    OpenAIResponseMessage,
+    OpenAIResponseOutputMessageContentOutputText,
+)
+from llama_stack.apis.inference import (
+    OpenAIChatCompletionContentPartTextParam,
+    OpenAIChatCompletionToolCall,
+    OpenAIChoice,
+)
+
+
+async def convert_chat_choice_to_response_message(choice: OpenAIChoice) -> OpenAIResponseMessage:
+    """Convert an OpenAI Chat Completion choice into an OpenAI Response output message."""
+    output_content = ""
+    if isinstance(choice.message.content, str):
+        output_content = choice.message.content
+    elif isinstance(choice.message.content, OpenAIChatCompletionContentPartTextParam):
+        output_content = choice.message.content.text
+    else:
+        raise ValueError(
+            f"Llama Stack OpenAI Responses does not yet support output content type: {type(choice.message.content)}"
+        )
+
+    return OpenAIResponseMessage(
+        id=f"msg_{uuid.uuid4()}",
+        content=[OpenAIResponseOutputMessageContentOutputText(text=output_content)],
+        status="completed",
+        role="assistant",
+    )
+
+
+def is_function_tool_call(
+    tool_call: OpenAIChatCompletionToolCall,
+    tools: list[OpenAIResponseInputTool],
+) -> bool:
+    if not tool_call.function:
+        return False
+    for t in tools:
+        if t.type == "function" and t.name == tool_call.function.name:
+            return True
+    return False

tests/unit/providers/agents/meta_reference/test_openai_responses.py

@@ -41,7 +41,7 @@ from llama_stack.apis.inference import (
 )
 from llama_stack.apis.tools.tools import Tool, ToolGroups, ToolInvocationResult, ToolParameter, ToolRuntime
 from llama_stack.core.access_control.access_control import default_policy
-from llama_stack.providers.inline.agents.meta_reference.openai_responses import (
+from llama_stack.providers.inline.agents.meta_reference.responses.openai_responses import (
     OpenAIResponsesImpl,
 )
 from llama_stack.providers.utils.responses.responses_store import ResponsesStore