scheduled messages - daylight saving time changes expected sending time.

[mawed]

• I have searched open and closed issues for duplicates
• I am submitting a bug report for existing functionality that does not work as intended
• I have read https://github.com/signalapp/Signal-Android/wiki/Submitting-useful-bug-reports
• This isn't a feature request or a discussion topic

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Bug description

Scheduling messages for a moment after a point of daylight - saving time reschedules the sending time by the change of time

Steps to reproduce

• schedule a message before a moment of clock change
• wait for daylight-saving time
• check the scheduled time, it will be shifted.

Actual result:
The message is sent by a shifted point of time

Expected result:
If I schedule a message for 8:00 o'clock, it should be sent at 8:00 o'clock, even if daylight saving time appears.

Device info

Signal version: 6.15.3

[greyson-signal]

Our introductory text to scheduled messages indicate that the message will be scheduled using the current timezone. Everyone has different expectations, but we found the most common expectation was that if someone schedules the message to go out at 8am, even if they get on a plane and move to a different timezone, they'd expect the message to be sent based on the timezone they were in during scheduling.

Now, daylight savings is a special case, because it's a timezone shift that occurs without travel :) So I could imagine people preferring something different here. But imo it's not quite worth it to make a complicated system of identifying daylight savings specifically and special-casing it in both the code and the user education.

Hope that clears things up :)

[TJ82]

I'm not sure if I would make the same assessment. I think that DST is a property of a timezone rather than a timezone in itself. Timezones with DST would then have a different UTC offset depending on the date.

To make a comparison: when I use any calendar app to plan something across a DST change it interprets the time as I would by the time the appointment actually is happening. So planning an appointment on 9:00 on a date past the next DST change would show up as 9:00 whenever I view this appointment in my calendar, regardless of whether the moment at which I view it is with or without DST. I think that it is a very reasonable expectation of users that scheduled messages in Signal behave the same.

@greyson-signal, would you be willing to reconsider your position on the matter?