The card and the table carried byte-identical copies of the day-label
arithmetic. Two copies is how they drift, and neither was reachable from a
test, which is why the double conversion in both survived review.
Lift it into resolveNextDueDayLabel, which returns a discriminated label the
callers map onto their own strings, and cover the case the old code could
not get right: a browser zone that differs from the profile zone. Those
tests pin the host zone explicitly — the defect was invisible whenever host
and profile agree, which is the only configuration a UTC-only suite runs in.
Also pin that the window-status verdict is identical from every host zone,
including one whose spring-forward gap swallows the profile wall clock.
Marc-André Bombeck
4ba600d908