[Feat] New LLM API Endpoint - Add List input items for Responses API

[ishaan-jaff]

[Feat] New LLM API Endpoint - Add List input items for Responses API

This PR adds a new “List Input Items” endpoint to the Responses API, wiring it through the client, router, proxy, and HTTP handler layers, and includes a basic async test.

• Introduces litellm.alist_input_items client methods (sync and async)
• Updates router, proxy routes, and HTTP handler to support the new endpoint
• Adds a smoke test for the new endpoint and necessary type/enum updates

Relevant issues

Pre-Submission checklist

Please complete all items before asking a LiteLLM maintainer to review your PR

• I have Added testing in the tests/litellm/ directory, Adding at least 1 test is a hard requirement - see details
• I have added a screenshot of my new test passing locally
• My PR passes all unit tests on make test-unit
• My PR's scope is as isolated as possible, it only solves 1 specific problem

Type

🆕 New Feature
✅ Test

Changes

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Name	Status	Preview	Comments	Updated (UTC)
litellm	✅ Ready (Inspect)	Visit Preview	💬 Add feedback	Jun 10, 2025 10:33pm

[Copilot]

Pull Request Overview

This PR adds a new “List Input Items” endpoint to the Responses API, wiring it through the client, router, proxy, and HTTP handler layers, and includes a basic async test.

• Introduces litellm.alist_input_items client methods (sync and async)
• Updates router, proxy routes, and HTTP handler to support the new endpoint
• Adds a smoke test for the new endpoint and necessary type/enum updates

Reviewed Changes

Copilot reviewed 12 out of 12 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
tests/llm_responses_api_testing/base_responses_api.py	Adds an async test for alist_input_items
litellm/types/utils.py	Registers alist_input_items in CallTypes
litellm/router.py	Formats annotations and hooks up alist_input_items
litellm/responses/main.py	Implements alist_input_items client functions
litellm/proxy/route_llm_request.py	Adds proxy routing for alist_input_items
litellm/proxy/response_api_endpoints/endpoints.py	Implements FastAPI proxy endpoint logic
litellm/proxy/common_request_processing.py	Includes alist_input_items in common processing lists
litellm/llms/openai/responses/transformation.py	Adds request/response transformers for list endpoint
litellm/llms/base_llm/responses/transformation.py	Declares abstract methods for list transformers
litellm/llms/azure/responses/transformation.py	Adds Azure request transformer for list endpoint
litellm/llms/custom_httpx/llm_http_handler.py	Implements sync/async handlers for list input items
litellm/model_prices_and_context_window_backup.json	Adds two new Mistral model entries

Comments suppressed due to low confidence (4)

litellm/proxy/response_api_endpoints/endpoints.py:242

• The handler refers to request but it isn't declared in the function signature. Add request: Request as the first parameter so _read_request_body(request=request) will work.

async def get_response_input_items(

tests/llm_responses_api_testing/base_responses_api.py:334

• The test prints the response but does not assert anything about its shape or contents. Consider adding an assertion (e.g. that it's a dict and contains expected keys like 'data').

list_items_response = await litellm.alist_input_items(

litellm/types/utils.py:278

• The new alist_input_items member should also be added to the CallTypesLiteral union so that type hints include this call type.

CallTypesLiteral = Literal[

litellm/llms/azure/responses/transformation.py:204

• Azure provider implements the request transformer but not transform_list_input_items_response. You need to add a response transformer (e.g. parsing .json()) to satisfy the abstract base class and handle responses correctly.

return url, params