The most recent values-channel snapshot emitted at the root
namespace — i.e. the thread-level state as the server sees it
after each superstep. Updated on every root values event, not
on token-level deltas: if you render stream.values.messages
directly you'll see full turns appear at once instead of
streaming token-by-token. Use messages (or
useMessages) for the token-streamed view.
Equivalent to calling useValues(stream).