Reviewing Changes
Whose writing the project marks as tracked changes is decided in the Users panel, a person at a time: anybody whose Changes there are Track or Suggest has their edits marked. There is one answer for the whole project: everybody on it sees the same changes marked, and accepting one settles it for all of them.
The review bar
Working through the changes happens in the bar along the bottom of the editor.
The left arrow and right arrow move to the previous and next change, crossing into other chapters when this one has no more. The green checkmark accepts the change the cursor is in, and the red cross rejects it. Beside them the bar counts the changes waiting across the book, with a chip for each person whose changes they are, in the colour their changes are highlighted in — or says No changes waiting. Changes your own AI agent made are counted separately — 3 changes waiting (1 from your AI), or 1 AI change to review when they are all there is — because reviewing them is between you and your agent, whatever the project tracks. While a book is still opening, the bar says Checking for changes… until it knows.
On the right, a button says how many people's edits the project is tracking — 2 users tracked, say, or No users tracked. No users tracked means whatever your collaborators write goes straight into the text. If you are an administrator, clicking it opens the Track Changes wizard, which asks whose changes to track and sets it up for you. Anybody else gets the Users panel, to see who is tracked.
The bar is always there, even with nothing to review, so you can tell at a glance whether anybody's edits are being marked.
Comments are not part of this: they have their own icon in the left rail, with its own count and its own filters for narrowing which of them the manuscript shows. See Collaboration, where adding, replying to, approving and deleting comments is covered.
Seeing the edits
Everything marked is shown as a tracked change, in the colour of the hand that made it; hover over a change to see who that was. Chapters that contain changes nobody has dealt with are marked in the chapter list.
Your own AI agent is the exception to all of this. Its work is always pending for you, whatever the project has decided, and it is labelled as your AI rather than your own typing and shown in its own colour — so a passage you wrote and a passage your agent rewrote are never confused for one another. A collaborator's agent is not told apart from the collaborator, because from where you are sitting the two are one hand. See the agent panel.
Not everything that changes a document is an edit to the text. Adding or removing an index entry marks a phrase for the index without altering a word of it, so it is not offered as a pending rewrite of that phrase. Formatting a passage, or changing a figure's settings, is shown as the change it is rather than as the passage being deleted and retyped — and accepting or rejecting one leaves any other edit made inside it alone.