Every other report here is about the buses. This one is about us: hours where this platform recorded materially less than it should have. An hour is compared against the same hour on comparable days, scaled to the service actually timetabled that day — without that scaling every bank holiday reads as an outage, because two thirds of the observations really are missing when two thirds of the buses are.
Every journey ends with its label moving on, so the count on its own means nothing. The question is how much of the journey was still to run when it moved, and the answer is almost always none: about a third switch with the journey complete and half with only the terminus left to pass. That is the label moving on arrival, which is normal and is not a fault.
Unfinished — two or more stops still to run — is about one in eight, and it holds two different things that should not be added together. Nearly home is a bus past halfway that lost its last few stops: the fault this is about, and the one worth taking to an operator. Barely begun is a bus re-badged with most of the route still ahead — 79 stops left of 90, 37 of 38 — which is not a bus abandoning a journey but a journey we had barely started tracking, so the re-badge is the symptom rather than the cause. Ranking on stops left alone just ranks by route length.
Where the next journey starts at the stop this one ends at, and the bus is within 600 m of it, the arrival is credited from the switch: the operator's own equipment putting a bus on to a journey that begins there is better evidence than a distance threshold. Beyond that nothing is written — a bus signing on to its next duty from somewhere else has not arrived anywhere.
Whether a day can be rebuilt is the part worth acting on. The live path writes observations as it reads the feed; the raw payload is kept separately, one file every twenty seconds. A day whose archive is intact could be rebuilt from those bytes. A day past the archive's retention is gone, and every figure that was ever drawn from it understates what ran.