We build software and write down how it works.

A Firefox extension that blocks the sites you name. Getting past a block costs deliberate effort instead of a click: you retype an eight-digit string by hand, no copying, and one mistake gets you a fresh one. That buys one site in one tab.

Turning blocking off everywhere is a Pause, and it expires after fifteen minutes. A site can go on the Block List at any time, but it can only come off during a Pause, so it never leaves in the moment you want it back.