Session Expiry

An alert dialog, named by its heading and described by the sentence that says how long is left. Escape and the backdrop do nothing, because dismissing a session warning without choosing is choosing nothing; the two buttons are the way out, and focus opens on the safe one. The visible countdown is not live — a number every second for two minutes drowns the question — and a separate status region speaks four times: when the warning opens, at one minute, thirty seconds and ten, still saying a threshold a slow tick skipped over. The clock is read in an effect, so the server renders nothing rather than a countdown from the wrong instant. This satisfies the warn-and-extend half of WCAG 2.2.1 Timing Adjustable; the twenty-second minimum is the default window's business and the application's.