What is the Codex?

The Codex is your book's story bible — everything the AI must know and never contradict while it writes: your characters (with age, personality, fears and more), your world (places, factions, important objects, hard rules like a magic system), and your own background knowledge (pasted notes or .md/.txt files).

Open any book in your Library and click the "Codex" button above the chapter list. Whatever you put there is automatically sent to the AI every time it writes — new chapters, regenerated chapters, "Extend with AI" and the outline — so facts stay consistent from the first page to the last. A book with an empty Codex is generated exactly as before; the feature is fully optional.