The book’s appendix is about assembling the pieces into a creature. This expansion combines the wind field (chapter 1), neural networks (chapter 10), and evolution (chapter 9) into agents that learn to sail.
Each agent has a tiny neural brain: its inputs are the local wind vector, the bearing to the goal, and its remaining fuel; its outputs are thrust and turn. Agents start at the left edge and try to reach a goal on the right, spending fuel as they go, while the real wind pushes them around. A genetic algorithm breeds the brains that got closest, so over generations the flock discovers strategies suited to the actual forecast, including tacking across an unfavorable wind. Change the day and the winning strategy changes with it, because the environment is a real, nonstationary thing.
Data source: Open-Meteo Forecast API
Endpoint:https://api.open-meteo.com/v1/forecast?latitude=...&longitude=...&hourly=wind_speed_10m,wind_direction_10m
Access: Public, no key. Loaded from an hourly server-side refresh when possible, with a bundled snapshot fallback, and a live browser fetch only when the API allows CORS. Data window: Jul 18, 2026 (pulled Jul 18, 2026 UTC)
Nothing is saved between runs; every reload starts evolution over from random brains.