The epicenter of the political earthquakes rattling San Francisco’s progressive establishment is a 30-square-block neighborhood in the center of downtown known as the Tenderloin. Adjacent to some of the city’s most famous attractions, including the high-end shopping district Union Square, the old money redoubt of Nob Hill, historic Chinatown, and the city’s gold-capped City Hall, it is home to a giant, open-air drug bazaar. Tents fill the sidewalks. Addicts sit on curbs and lean against walls, nodding off to their fentanyl and heroin fixes, or wander around in meth-induced psychotic states. Drug dealers stake out their turf and sell in broad daylight, while the immigrant families in the five-story, pre-war apartment buildings shepherd their kids to school, trying to maintain as normal an existence as they can….