A chapter or section heading ends up as the last line of a page in my export. How do I fix it?

You don't have to — BookyAI's layout engine guarantees it can't happen. In both PDF and Word exports, a heading always stays on the same page as the text that follows it: if a heading would land at the very bottom of a page, it automatically moves to the top of the next page together with its paragraph. The same protection prevents "widows and orphans" — a paragraph never leaves a single lonely line at the top or bottom of a page. This works at every trim size, so you never need to place headings manually or add empty lines to push content around. If you're on an older version and see a stranded heading, update BookyAI and export again.