Story bible
A story bible — called a series bible when it spans multiple books — is a reference document that records the fixed facts of a fictional world: character names, appearances, and relationships; places; magic or technology systems; and the timeline of events. Its job is to keep those facts consistent as the story grows.
The core sections are fairly standard. Characters: everything from eye color to secrets and speech habits. Places: geography, distances, what each location looks like. Systems: the rules of magic, technology, politics, or religion, including their limits. Timeline: what happened when, both on the page and in backstory. The bible is where you check whether the innkeeper had a beard in book one before you shave him in book three.
The common failure mode is a bible that lives in scattered notes and drifts out of date, so contradictions creep in anyway. In Scribegrove, the series itself holds the canon — main characters, locations, and systems live at the series level and every book in the series generates and checks prose against them, so the bible is enforced rather than merely written down.