Comments
The comment box under a published page is switched off for now; what follows is how comments work when it is back.
Under every published page, anyone with the link can leave a comment, with a name or without. The discussion that built the page is told the new ones at its next run — as readers' words to weigh, never as instructions — and can rewrite the page in answer; the link stays the same. The owner can take a comment down from under the page. The Artifacts list on the web and the iPhone shows how many comments a page has and how many the room has not read yet.
On the Mac the same happens for a page a run published from a checkout: before the next run in that discussion, the Mac asks the server what readers said and gives it to the lead with the brief.
Earlier versions
Every rewrite keeps the version it replaced. The owner sees a version menu above the page, can look at an earlier one, and can make it the current one again; the link never changes, and the page as it is now is kept as a version too. The last twenty are kept. Readers see only the current page.
A page's own store
A page can keep a small store of its own — a tracker's rows, a sign-up sheet's names — that its viewers write to, so a page the room built can be used, not only read. The page has no network of its own, and still has none: it asks the viewer around it over a window message, and the viewer talks to the server for it. A value is JSON up to 8 KB; a page keeps up to 200 keys; anyone with the link can read and write, and the owner can empty the store from the version bar.
The room is told how to use the store when it publishes, so asking for "a sign-up page people can put their name on" is enough. A page opened by its raw link, with no viewer around it, gets no answers from the store and must still render.
When not to use it. For anything that must be private, or anything that must not be lost: the link is the only lock, and the store is emptied with the page.