Example: experimental_streamData, server Timestamps, and client messages

[peterdresslar]

Hello, I've added to my sandbox repo with an example of running timestamps from the server to the client using experimental_streamData to send a server-generated timestamp to the client as data, just to get a good feel for how well that works. (and to address issue #647.)

There are a few tricky aspects, including extending the shared type Message and understanding how useState rerenders for the useChat helpers. However, the good news is that the data object does update in a predictable manner, at least in testing.

The code is in this repo: the route is under /chat/openai-experimental-streamdata, and the component is openai-experimental-streamdata-timestamps.tsx.

You can test it online at this site by choosing the OpenAI with Experimental Stream Data Timestamps option.