The Manual for the Modern Ninja: Thresholds

Most people get trapped where one space becomes another.

Thresholds is a practical field manual for reading doors, entries, exits, elevators, stairwells, parking structures, vehicle approaches, and all the narrow transition points where routine makes people easy to control.

This is not fantasy ninja material. It is modern civilian tradecraft for crossing thresholds on your terms, staying out of funnels, and keeping a narrow place from making the decision for you.