Twenty-two chapters, assembled: one repository configured end to end in the order that makes each layer cheap, the question underneath every decision in this handbook, and where the road goes after the CLI.

Four pages cover every failure, and the first job is knowing which one you are on. The routing question, the commands that show what actually loaded, and the handful of location mistakes behind most configuration surprises.

Four settings files, one precedence stack, and the handful of keys that break the stack's rules. Where each file reaches, why some keys merge instead of overriding, and how to find out which file is beating yours.