# Thread Weave Contract

- The core unit is exact canonical page/window → exact canonical page/window.
- Thread coherence beats catalogue utilisation.
- Do not force a Book into a route to increase coverage.
- Every cross-Book handoff must privately justify: carried idea, change, exact-page choice, and relation to the original thought.
- A Thread may enter a Book midway and leave before it ends. The Book itself remains complete.
- Exploring a Book never creates or replaces the active Thread.
- A complete Thread must never depend on paid missing material for coherence.
