A departure board changes state and then holds still. That is the whole design rule behind Sherpsy's screens: things appear, things update, and nothing drifts, slides, or shoves its neighbours around while you are reading. Last week we found a place where the rule was being broken, and only on the connections where it would hurt most.
Invisible on a fast connection
The Alert Center sits between the dashboard header and the board. It used to fetch its own alerts after the page arrived, and render nothing until they landed. On an office connection that took a few milliseconds and nobody saw it. On a throttled phone it took several seconds — and when the alerts finally appeared, every panel below them dropped about 350 pixels. If you were reaching for a chore at that moment, you tapped something else.
We measured it on production under a slow-network profile: a layout-shift score of 0.16, five runs out of five, comfortably past the threshold Google calls poor. On a fast connection the same page scored a clean zero, which is exactly why it had survived.
The fix we did not take
The textbook answer to layout shift is to reserve the space: draw an empty box where the alerts will go, so nothing moves when they arrive. We refused it. The Alert Center exists on one condition — that when there is nothing to say, it is not there at all. A permanent blank slot where the alarm lives would teach you to look past that spot, and that is the one spot you must never look past.
An empty box where the alarm lives is worse than a jump.
So the alerts now arrive with the page. The dashboard was already assembling several queries on the server before sending the first paint; the alerts joined that same batch. The strip is in the very first HTML, the client picks it up without a second request, and the score is now zero on the slow profile too. Same rule, kept both ways: it is either there from the start, or it is not there.