Live collaboration
Two people can open the same chapter and write in it at the same time. Edits appear as they are typed, each person's cursor is visible to the other, and nobody has to take turns or copy anything back and forth.
What it does
Rich-text fields — a chapter's text and synopsis, a character's biography, and the descriptions on creatures, events, entries, locations, organizations and places — become shared documents while they are open. Changes merge rather than overwrite: two people typing in different paragraphs both keep their work, and two people typing in the same one end up with both sets of words rather than whichever save landed last.
The save indicator says saving live while a field is shared. There is nothing to save — the text is already with everyone who has it open.
What happens when the connection drops
Your editor keeps working. Edits made while disconnected merge when the connection returns, and the stored copy is rebuilt from the database if the two ever disagree. A document is never left holding work that only exists in one browser.
Who can use it
Reading and writing follow the role you already have in the project. A member with read access sees the text update live and sees other people's cursors; a member without write access cannot change it, and the server checks that on every message rather than trusting the editor. Losing access to a project closes the document you had open.
Why it is being rolled out gradually
A shared document lives in the memory of one server process, which puts a real ceiling on how many can be open at once and how the service can be scaled. It is being switched on per account and per project so that ceiling is approached deliberately rather than discovered.