Warn before a timeout cuts listening, or people get dropped in the middle of a pinch

What it is

A timeout that cuts on the tick will drop people who were aiming, or who had just started to pinch. The next command has to sign in again. A warning is a perceptible “listening is about to stop” before the real leave, so people can emit a keep-alive or accept the leave. Timeout with no warning feels like random power loss. A warning does not make the timeout longer. It makes the cut expected. The duration trade remains; the warning makes the short end of the trade less injuring.

Why it happens

People cannot internalize an invisible idle clock. When the clock empties, internal state flips with no external preparation, and an in-flight servo (aim, drag) is pinched off. A warning externalizes the last stretch of the clock: a bar, a pitch change, a blinking cursor. Once external, people can fire a cheap keep-alive edge (a small move, another pinch) that resets the clock, or let it run out. The keep-alive must not look like a command, or the warning period false-fires business functions. Too short a warning is none. Too long secretly moves the timeout operating point. The warning must also be mutable: for someone already walking away, a countdown becomes noise.

Studying it

Same timeout operating point, compare no warning, short warning, long warning. Tasks include mid-aim and continuous drag. Measure: whether people were doing work at the cut, whether keep-alive succeeded, false commands from the warning itself, and rated “got dropped.” Warning channel (visual / sound) as a factor. Trials where people walk away and do not mean to keep-alive show whether the warning calls them back—that may be too long. Do not measure warnings on idle sitting with no in-flight action; those cuts never hurt.

Where it stops holding

A public terminal whose person has already left the frame has nowhere to send a warning; leave immediately. A fully screenless, silent embedded device can only warn with a lamp or a buzz. Continuous drag should pause timeout, so a warning should not appear mid-drag; it appears after release, once idle starts the clock. If the warning shares a form with entry or command feedback, people will read it as another click. Accessible: a visual-only countdown is nothing to someone not looking at the screen.

Applying it

• Before a timeout actually cuts, emit a perceptible warning and offer a keep-alive edge that does not fire a business command.
• Spec warning duration on its own; do not squeeze it out of the timeout. No warning during in-flight continuous manipulation.
• Accept on two columns: “cut mid-aim” and “called back after already leaving.” The first should be rare, the second should not happen, or the warning is not connected.

Related

• Same group: C4.16.1 Leave can be explicit or automatic · C4.16.2 Timeout length trades unexpected cuts against timely release · C4.16.4 Explicit leave should be symmetric with entry, for memory
• Adjacent: C4.11 Substitutes for contact feedback · C4.19 Re-entry grace
• Search: timeout warning · session expiring · keep-alive