Chapter list — click to open notes
Concept map — click a node to trace its connections
amber = selected · lit nodes = direct connections · scroll sideways on small screens
SECTION A
How the architecture evolves
5 STAGES — each fixes what the last one broke
SECTION B
Where each concept lives in one request
CLIENT → DATA, LEFT TO RIGHT
click any pin to open its notes · B2 / B3 sit above the strip because they govern the whole contract, not one hop