Hard facts about the world. Every entry here is a constraint the evaluator checks against. If the prose contradicts canon, it's a bug.
This file grows during foundation and drafting. When a fact is established (in world.md, characters.md, or in a chapter), it gets logged here as canonical. The evaluator cross-references canon against every chapter.
Each entry: a short, falsifiable statement with the source. Group by category. Keep it flat and scannable -- this isn't prose, it's a database.