How to read this book

This handbook has three kinds of chapters. Knowing which is which keeps the record honest.

Chapter status labels

Every chapter opens with a status line:

Built & verified, the feature is shipped and works end to end.
In progress, partially built; the chapter says exactly what works and what does not yet.
Spec — not shipped, a mechanism with a clear target shape, documented with the failure mode it fixes. Spec chapters do not claim the work is done.

Provenance. When a technique is adapted from prior art, the source and its license are named briefly and collected in Acknowledgements. Veyyon adapts MIT/Apache code with attribution and studies proprietary code clean-room.
Numbers have sources. A quoted measurement names who measured it. Veyyon’s own numbers are marked as such; cited third-party numbers are marked as theirs.
The lever. Each optimization names which thesis lever it moves, edit format, control flow, or a supporting concern (cost, robustness, coherence). If it doesn’t move a lever, it doesn’t belong.