feat: add responses input items api (#2239)

# What does this PR do?
TSIA

## Test Plan
added integration and unit tests

llama_stack/apis/agents/agents.py

@@ -31,6 +31,7 @@ from llama_stack.apis.tools import ToolDef
 from llama_stack.schema_utils import json_schema_type, register_schema, webmethod
 
 from .openai_responses import (
+    ListOpenAIResponseInputItem,
     ListOpenAIResponseObject,
     OpenAIResponseInput,
     OpenAIResponseInputTool,
@@ -630,3 +631,25 @@ class Agents(Protocol):
         :returns: A ListOpenAIResponseObject.
         """
         ...
+
+    @webmethod(route="/openai/v1/responses/{response_id}/input_items", method="GET")
+    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. Limit can range between 1 and 100, and the default is 20.
+        :param order: The order to return the input items in. Default is desc.
+        :returns: An ListOpenAIResponseInputItem.
+        """
+        ...

llama_stack/apis/agents/openai_responses.py

@@ -216,7 +216,7 @@ OpenAIResponseInputTool = Annotated[
 register_schema(OpenAIResponseInputTool, name="OpenAIResponseInputTool")
 
 
-class OpenAIResponseInputItemList(BaseModel):
+class ListOpenAIResponseInputItem(BaseModel):
     data: list[OpenAIResponseInput]
     object: Literal["list"] = "list"
 

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

@@ -20,6 +20,7 @@ from llama_stack.apis.agents import (
     AgentTurnCreateRequest,
     AgentTurnResumeRequest,
     Document,
+    ListOpenAIResponseInputItem,
     ListOpenAIResponseObject,
     OpenAIResponseInput,
     OpenAIResponseInputTool,
@@ -337,3 +338,16 @@ class MetaReferenceAgentsImpl(Agents):
         order: Order | None = Order.desc,
     ) -> ListOpenAIResponseObject:
         return await self.openai_responses_impl.list_openai_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:
+        return await self.openai_responses_impl.list_openai_response_input_items(
+            response_id, after, before, include, limit, order
+        )

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

@@ -14,10 +14,10 @@ from pydantic import BaseModel
 
 from llama_stack.apis.agents import Order
 from llama_stack.apis.agents.openai_responses import (
+    ListOpenAIResponseInputItem,
     ListOpenAIResponseObject,
     OpenAIResponseInput,
     OpenAIResponseInputFunctionToolCallOutput,
-    OpenAIResponseInputItemList,
     OpenAIResponseInputMessageContent,
     OpenAIResponseInputMessageContentImage,
     OpenAIResponseInputMessageContentText,
@@ -164,7 +164,7 @@ async def _get_message_type_by_role(role: str):
 
 
 class OpenAIResponsePreviousResponseWithInputItems(BaseModel):
-    input_items: OpenAIResponseInputItemList
+    input_items: ListOpenAIResponseInputItem
     response: OpenAIResponseObject
 
 
@@ -223,6 +223,27 @@ class OpenAIResponsesImpl:
     ) -> 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 create_openai_response(
         self,
         input: str | list[OpenAIResponseInput],

llama_stack/providers/utils/responses/responses_store.py

@@ -7,6 +7,7 @@ from llama_stack.apis.agents import (
     Order,
 )
 from llama_stack.apis.agents.openai_responses import (
+    ListOpenAIResponseInputItem,
     ListOpenAIResponseObject,
     OpenAIResponseInput,
     OpenAIResponseObject,
@@ -96,3 +97,39 @@ class ResponsesStore:
         if not row:
             raise ValueError(f"Response with id {response_id} not found") from None
         return OpenAIResponseObjectWithInput(**row["response_object"])
+
+    async def list_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 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.
+        """
+        # TODO: support after/before pagination
+        if after or before:
+            raise NotImplementedError("After/before pagination is not supported yet")
+        if include:
+            raise NotImplementedError("Include is not supported yet")
+
+        response_with_input = await self.get_response_object(response_id)
+        input_items = response_with_input.input
+
+        if order == Order.desc:
+            input_items = list(reversed(input_items))
+
+        if limit is not None and len(input_items) > limit:
+            input_items = input_items[:limit]
+
+        return ListOpenAIResponseInputItem(data=input_items)