Race Engineer turns your measured fuel burn into a pit window: the earliest lap you can safely stop and the latest you still can.
Once a stop is needed, Race Engineer computes a window: the earliest lap you could pit, the latest lap it's still safe to, and the recommended lap in between. The window opens a few laps before the deadline, so you have room to react to traffic or a better opportunity. Instead of a single lap number that's either right or already too late.
The pit window is built from your fuel prediction: measured burn per lap and the race distance left. Tire wear and pace are not part of this calculation yet; a strategy that weighs them together is planned.
Laps run slow behind a caution are left out of your fuel average, so the window stays accurate once racing resumes. While a caution is out, the recommendation says so.
At very low fuel margins, the window calculation can disagree with itself by a lap or two, a known edge case in lap-integer math. Race Engineer resolves that by trusting the fuel prediction that already said a stop is needed and recommending you pit this lap, rather than leaving you with no window and no action at the exact moment it matters most.
Not yet. Today the window is built from fuel only. Tire-aware strategy is planned.
Three lap numbers: the earliest lap you could safely stop, the latest lap it's still safe to, and a recommended lap in between.
It does not move the pit lap. Slow caution laps are left out of the fuel average, so the numbers stay right afterwards, and the recommendation notes when a caution is active.
Then there's no pit window at all. Race Engineer only computes one once the fuel numbers say a stop is actually needed.