Support userData on participants #41

Use case

I'm using the DailyTransport in Pipecat. I want to read and subscribe to user data so my bot can be aware of it.

Expected behavior

I expected that when calling setUserData (for example, when raising my hand with the prebuilt UI), the user's data will update triggering on_participant_updated with the latest data. I also expect to be able to read user data when the participant joins in on_participant_joined.

Actual behavior

In practice, the event doesn't fire and I don't see a way to read userData from participants with the underlying Python SDK.

A Daily maintainer mentioned here the Python SDK doesn't support userData yet, and as a workaround suggested using app messages to initialize and sync user data to Python, which is inconvenient.