The scheduler's day picker began on Sunday because that is where Intl
numbers the days from, which is a fact about the API and not about
anybody's week. Monday leads it across most of Europe. A row of seven
buttons in the wrong order is not just odd to read — it is easy to
misclick, and a misclicked day in a schedule is a car charging on the
wrong night.
So Settings › Appearance asks, beneath the date and the clock, as the
third question a region gets: first day of the week, following the region
unless it is answered outright. The same shape the time format already
had, and the same "auto" default, so nothing changes for an account that
never opens it.
The rule lives in lib/format.js beside the clock's, with the ordering, the
day names and the sort all coming from there. The two places that lay
weekdays out — the picker and the line each task is summarised on — read
it rather than each keeping an opinion, so a day set is written and read
back in the same order.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>