That’s still a different thing: it’s a recurring event, which is an almost entirely separate can of worms from a datetime. And a recurrence library probably wa

That’s still a different thing: it’s a recurring event, which is an almost entirely separate can of worms from a datetime. And a recurrence library probably wants to avoid libc-style “localtime” here — plumbing the concept of users in places to it seems awkward. A genuinely naive time may be better — the interface could be “calculate the next recurrence of this recurring event in this timezone,” not “here’s a recurring event with associated ‘local’ time — calculate the next occurrence given my /etc/localtime and TZ environment variable”.