Everything a site needs past the first screen — an about page, a blog, a
contact page — had to live on that one page or not exist. The folder on Sia
could always hold more; the studio could only ever edit index.html.
Pages are now a list. Each one is a folder with its own index.html, so it
answers to the address a visitor would guess (/about/), and the sidebar
shows that address rather than the file behind it. The title is editable and
the address is not: a published URL that moves is a link somebody else wrote
down and can no longer follow.
Draft and Publish both walk the whole list. Pages that link to each other
are only coherent if they go up together, so there is one button and it
sends everything, writes a sitemap when there is more than one page, and
sweeps deleted pages off Sia in the same pass instead of leaving them
serving. A site saved before this opens as a single home page and gains the
rest when asked.
Two things that would otherwise be quietly wrong: assets exported from a
sub-folder page now carry the ../ that makes them resolve, and loading a
page into the editor no longer registers as an edit.