What does the Consistency check do?

It is a proofreader for facts. Open the book, click "Codex" above the chapter list, go to the Check tab and press "Run consistency check". The AI rereads every finished chapter against your story bible — characters, world rules, background knowledge, open threads, and (for a series) the earlier books — and flags contradictions such as "her eyes were grey in chapter one, blue here". Each finding shows the severity, the conflicting quote and what it contradicts; click a finding and BookyAI opens that chapter in the editor at the exact passage so you can fix it. The check runs one AI request per chapter, so a 20-chapter book uses 20 requests from your API key.