The event form held its times and their UTC offsets as four separate
fields, so any change to a time had to remember to refresh or clear its
offset. A form time is now one FormTime: the wall clock plus the offset it
was read at when the fall-back hour repeats it. Setting a time sets both, so
the two can't drift apart. Wall-clock meaning is unchanged: an unpinned form
still follows the device zone, a zone switch keeps the wall clock and
all-day forms stay dates.
- A pass switch now shows up in the form itself, so saving no longer
compares the written times separately.
- The editor's view model reads the device zone through a seam, and tests
cover a draft opened across the fall-back hour and in the spring-forward
gap.