The note about the overlay target was separate from the streaming.

I would put the turbo_stream_from in the code where it made sense. If the modal is being dynamically rendered (so once you close it or another modal pops up and replaces this chat one) then it would make sense to have the turbo_stream_from inside of the modal so it will be disposed when the modal is replaced or destroyed.

If you want to receive the streams even when the modal is closed or not preset (updating some other parts of the page like an unread message count) then it should exist outside of the modal code.

Hope this makes sense.