Full manuscript read-through
The editor reads the whole manuscript start to finish, noting anything that should change: awkward phrasing, pacing, the timing of descriptions, the feel of a passage. The notes are then worked through as a dedicated pass.
The Companion guide, alongside the read-through
Built entry by entry in book order, in parallel with the read-through, since proofreading for phrasing and feel does not change the facts it records. Each entry's section has terms and lore, characters (personality and where they stand, with a slot for a picture), questions, and fun facts; The Missing Links closes the guide and is already drafted. Once an entry has been proofread, its section gets a quick check against the revised text. Done: The Book of Prophecies and Dark Road. Next: Birth by Sleep, rebuilt from scratch.
Release-order edition
A second, separate edition of the book in the order the games came out, built from the same entry files. The chronological book stays as it is. Relocated scenes (Blank Points, Aqua's Final Mix episode, the opening of Kingdom Hearts III) go back to their own games, each entry is checked for what it assumes the reader knows, and the Companion gets the changes listed in release-order-notes.txt, which is kept up to date as each Companion section is written.
Images, last of all
Once everything above is done: mark where images belong in the book and add them, together with the Companion's character pictures.
The read-through above is yours; everything else is a candidate for the next work session, not yet started.