The public housing where 400,000 New Yorkers live has in far too many cases fallen into disrepair. Leaks are chronic. Rodents run rampant. Mold grows. Elevators break and await repairs. Entry doors have broken locks. So do boilers and gas burners. All told, the cost of outstanding fixes adds up to an impossible-to-fathom $78 billion, up from an estimated $45 billion just a few years ago. That’s just the monetary cost; the mounting psychological weight on residents is immeasurable.