Improve documentation: Expected response structure for useChat custom endpoints

[tomtitherington]

Feature Description

When using the useChat hook, I'd like to know what the expected structure of the data returned from the endpoint specified by the api parameter is:
https://sdk.vercel.ai/docs/reference/ai-sdk-ui/use-chat#:~:text=api%3F%3A,an%20absolute%20URL.

I can't find any explicit reference to the structure or shape of this data anywhere in the docs.

Use Cases

I'd like to keep using the UI library with my own custom LLM (that doesn't support streaming).

Additional context

No response

[lgrammel]

Is https://sdk.vercel.ai/docs/ai-sdk-ui/stream-protocol what you are looking for?