LLM Analytics: Provider wrappers don't respect context distinct_id.

[ethanporcaro]

Bug Description

I'm using PydanticAI for LLM agents in Python. I wrapped it in the AsyncOpenAI from the posthog Python library, and am getting the traces correctly.

However, I am setting the distinct ID for posthog at a context level, and it seems that is not respected by the wrapper. Looking into openai_Async.py, I see that the distinct ID can be provided through the OpenAI-compatible methods such as openai.responses.create, but PydanticAI doesn't care about passing any of those through. I think it defaults to the trace ID.

I should be able to call identify_context and have it stored.

Mininum reproducable sample

import asyncio
import os

import dotenv
import posthog
from posthog import identify_context
from posthog.ai.openai import AsyncOpenAI
from pydantic_ai import Agent
from pydantic_ai.models.openai import OpenAIChatModel
from pydantic_ai.providers.openai import OpenAIProvider

# Required env.
# Or just hardcode it.
"""
POSTHOG_API_KEY=
OPENAI_API_KEY=
OPENAI_ENDPOINT=
AI_MODEL=
"""
dotenv.load_dotenv()

POSTHOG_API_KEY = os.getenv("POSTHOG_API_KEY")
posthog_client = posthog.Posthog(POSTHOG_API_KEY, host="https://us.i.posthog.com", debug=True)

client = AsyncOpenAI(
    api_key=os.getenv("OPENAI_API_KEY", ""),
    base_url=os.getenv("OPENAI_ENDPOINT", "http://localhost:1234/v1"),
    posthog_client=posthog_client,
)
model = OpenAIChatModel(
    os.getenv("AI_MODEL", "qwen/qwen3-vl-30b"),
    provider=OpenAIProvider(openai_client=client),
)
agent = Agent(
    model=model,
    system_prompt="Repeat the word you get ten times."
)


async def main():
    with posthog_client.new_context():
        identify_context("test_user")

        posthog_client.capture("test_event")  # Correctly uses distinct_id.
        print(await agent.run("posthog"))  # Does not log distinct_id.


if __name__ == "__main__":
    asyncio.run(main())

Additional context

I am using FastAPI and setting the context in the middleware. However, the result is the same as the independant sample above.