content_index missing in streamed response

[nivibilla]

Bug Title

content_index missing in streamed response

Description

hi,

Im using this as a /responses api provider inside the openai agents sdk along with ChatKit sdk for rendering UI

Im getting this error

                     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
pydantic_core._pydantic_core.ValidationError: 1 validation error for AssistantMessageContentPartTextDelta
content_index
  Input should be a valid integer [type=int_type, input_value=None, input_type=NoneType]
    For further information visit https://errors.pydantic.dev/2.12/v/int_type

The AssistantMessageContentPartTextDelta is expected a content_index param to be not None.

I think this traces back to the openai text delta event but not sure how to fix it.

Steps to Reproduce

Need to setup Chatkit, OpenAI Agents

Expected Behavior

setup works fine with using raw vllm server

Actual Behavior

                     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
pydantic_core._pydantic_core.ValidationError: 1 validation error for AssistantMessageContentPartTextDelta
content_index
  Input should be a valid integer [type=int_type, input_value=None, input_type=NoneType]
    For further information visit https://errors.pydantic.dev/2.12/v/int_type

[OriNachum]

Thank you for the bug, I will add to the queue after the existing 2 items (Unless this is a blocker - then let me know)

Note I am also maintaining a couple more open source repos and projects, so I balance my work.

[nivibilla]

Thanks @OriNachum , it's not fully a blocker per say. I'm able to use chat completions as a workaround but that has a few bugs of its own.

openai/openai-chatkit-advanced-samples#6

Im thinking to just write my own chat completions parser for ChatKit but ideally using responses API would be good. And no worries about the other project. Lmk if you need any more information.

[OriNachum]

I see! This really helps.

It works well for me when I use Codex, but I want to support chatkit as well.

Much appreciated!