Timeout warning

Somewhere in the building a security policy decided that fifteen minutes of quiet means you have left. Meanwhile a real person is on page three of a benefits claim, reading it twice because it matters, or typing with a head pointer, or having gone to find the document the form asked for. The next click posts a form nobody is signed in to any more and the answers are gone. This is a timing problem that lands hardest on the people who need the most time, which is why WCAG treats it as an accessibility criterion rather than a product decision.

Timing Adjustable (2.2.1, level A) sets out what you owe them. Either the limit can be turned off, or it can be extended to ten times the default before it starts, or the user is warned before it expires with at least twenty seconds to respond and can extend it with a simple action, at least ten times over. Twenty seconds is a floor and a low one, so give a minute where you can. The related criteria fill in the rest: Timeouts (2.2.6) says warn about data loss unless the data survives, and Re-authenticating (2.2.5) says that when the session does die and they sign back in, their work has to still be there.

The dialog itself is the easy part, and it is mostly restraint. Warn early enough to be useful, name what is at stake (“your application is not saved yet”) rather than just counting, and make extending one press of one clearly labelled button. Set the countdown in tabular figures so the number cannot jitter while somebody is reading it, and give the reader an explicit way out in both directions, extend or sign out now, instead of leaving the dialog to resolve itself. Announce it: the person who needs it most may not be looking at the screen.

It is worth saying which clock this is. A countdown timer on a checkout page is pointed at the reader, manufacturing urgency in the seller’s interest, and the honest ones are still doing that. A timeout warning points the other way: it is the system admitting it is about to do something destructive and asking permission first. The best version of it is a session long enough, and an autosave good enough, that the dialog never has to appear.