Why isn't `streamUI` used?

Hi, thanks for this work.

I'm trying to reconcile this implementation with the docs and am wondering why the streamUi method is not used. Instead, streamText is used and then its result is analyzed within a large if-else block where the correct UI is then sent via a stream created via createStreamableUI. Wouldn't streamUI have been cleaner, where the various tools could have been defined alongside their respective generate functions?

Thanks!