Output response types are not usable as parameters

[colinmarc]

Confirm this is an issue with the Python library and not an underlying OpenAI API

• This is an issue with the Python library

Describe the bug

Consider the following code:

messages: ResponseInputParam = [{"role": "developer", "content": instructions}]

# ...
resp = client.responses.create(
    model="o4-mini",
    input=messages,
)

for item in resp.output:
    match item:
        case ResponseOutputMessage(content=content):
            print(item.content)
            messages.append(item)

This seems like it should work fine, but it generates a type checking error:

error: Argument of type "ResponseOutputMessage" cannot be assigned to parameter "object" of type "ResponseInputItemParam" in function "append"
    Type "ResponseOutputMessage" is not assignable to type "ResponseInputItemParam"
      "ResponseOutputMessage" is not assignable to "EasyInputMessageParam"
      "ResponseOutputMessage" is not assignable to "Message"
      "ResponseOutputMessage" is not assignable to "ResponseOutputMessageParam"
      "ResponseOutputMessage" is not assignable to "ResponseFileSearchToolCallParam"
      "ResponseOutputMessage" is not assignable to "ResponseComputerToolCallParam"
      "ResponseOutputMessage" is not assignable to "ComputerCallOutput"
      "ResponseOutputMessage" is not assignable to "ResponseFunctionWebSearchParam"
    ... (reportArgumentType)

I think this is because the parameter types use Required, but the output types don't. For example, EasyMessageInputParam requires content, but ResponseOutputMessage doesn't:

openai-python/src/openai/types/responses/easy_input_message_param.py

Lines 13 to 18 in ed53107

	class EasyInputMessageParam(TypedDict, total=False):
	content: Required[Union[str, ResponseInputMessageContentListParam]]
	"""
	Text, image, or audio input to the model, used to generate a response. Can also
	contain previous assistant responses.
	"""

vs

openai-python/src/openai/types/responses/response_output_message.py

Lines 20 to 21 in ed53107

	content: List[Content]
	"""The content of the output message."""

I recognize that the bindings are auto-generated and this may not be trivial to fix.

To Reproduce

n/a

Code snippets

OS

linux

Python version

Python v3.13.2

Library version

openai v1.75.0