A live run on a real web build showed reads per edit going up, not down:
after each of its own writes lands the editor reads the page again
(refresh), and that one-shot page:getSnapshot read had been answered from
the live page:getSnapshot at no cost. With the page watched in slices it ran
in full every time. Opening a page also read it twice: once to show it, then
again in slices.

So a page is now watched whole at first, as before (the read just before
costs nothing more), and switches to slices only once it changes while
watched, and only if it is large enough for more than one slice. A page
watched in slices is read once through the same slices, which the client
answers from the live ones. The editor no longer passes a size hint: the
first answer gives it.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>