Keeping a story world consistent is one of the hardest invisible skills in fiction writing. If you’ve ever been deep into a fantasy series and suddenly noticed that a character’s eye colour changed between book two and book four, you know exactly what it looks like when that skill breaks down. One small inconsistency and the spell breaks. You’re no longer in the world. You’re holding a book, written by a human who made a mistake. What’s surprising is that failing to keep a story world consistent happens even to experienced, bestselling authors working with full editorial teams and years of time. Brandon Sanderson’s Cosmere spans over a dozen interconnected novels. Terry Pratchett’s Discworld ran for 41 books across three decades. George R. R. Martin’s Westeros has a history stretching back thousands of in-world years. Keeping it all straight isn’t a matter of memory or dedication. It’s a matter of systems. So what do professional authors actually do to keep their story worlds consistent? And what can readers learn about craft by understanding the answer? …