Found by driving the page I had just shipped. The two-step confirm of 0.61.0
disarmed itself after five seconds, on the reasoning that a control left armed
is one that gets pressed by somebody who has forgotten why it looks like that.
That is the right worry and it was the wrong remedy: a press on a control that
has quietly disarmed ARMS IT AGAIN, so anybody slower than the timer never
reaches the second press at all. Measured on the running interface: three
presses on Clear, each more than five seconds after the last, and nothing
happened - the button sat there saying "Clear?" forever.
The reading is worse than the driving. The armed label is a sentence - "Press
again to clear. The agent forgets everything you have told it. Its browsers
stay open." - which a screen reader takes some seven seconds to say. So the
control disarmed itself midway through announcing what the next press would do,
locking out exactly the person who needed the sentence read to them.
It disarms when it loses the focus now. A press moves the focus to what was
pressed, so leaving it is what says the attention has moved on - for a pointer
and for a keyboard alike. There is no number to choose, which is better than
choosing a new one: the worry was never about TIME, it was about attention
having moved on, and that is a thing the browser already reports.
Suite 621 green. Three known-bad inputs, three killed: the timer back, leaving
the control not disarming it, and disarming without dressing the control back.