The 5-minute journey

Before the theory, feel the shape of it. This is the interactive walk-through — problem → reasoning → decision — embedded live. Scroll it; click the ladder rungs and answer the decision tool at the end.

If the frame is cramped, open it full-screen: assets/journey.html

Everything in that frame is expanded, corrected, and cited in the chapters that follow. The frame is the map; the chapters are the territory.