Whole-day appointment with custom repeat period sometimes gets doubled

[LouisStrous]

Checklist

• [x] I can reproduce the bug with the latest version given here.
• [x] I made sure that there are no existing issues - open or closed - to which I could contribute my information.
• [x] I made sure that there are no existing discussions - open or closed - to which I could contribute my information.
• [x] I have read the FAQs inside the app (Menu -> About -> FAQs) and my problem isn't listed.
• [x] I have taken the time to fill in all the required details. I understand that the bug report will be dismissed otherwise.
• [x] This issue contains only one bug.
• [x] I have read and understood the contribution guidelines.

Affected app version

1.2.0

Affected Android/Custom ROM version

Android 15

Affected device model

Pixel 6a

How did you install the app?

Google Play Store

Which calendar service or provider do you use, if any?

none

Which sync adapter app do you use for calendar synchronization, if any?

none

Steps to reproduce the bug

1. Create a whole-day appointment for 25 April 2008 that recurs indefinitely every 500 days.
2. Create a whole-day appointment for 2 September 2009 that recurs indefinitely every 500 days.
3. Look for the appointments and their recurrences in later years.

Expected behavior

I expect the appointments and their recurrences to cover a single whole day each.

Actual behavior

Roughly 1/3rd of the recurrences cover two consecutive days, the correct one for the 500-day sequence but also the preceding day (499 days after the previous correct day).

Between 2008 and 2026 inclusive, the bad two-day recurrences of the 2008-04-25 appointment start on 2011-01-14, 2015-02-22, 2017-11-18, 2021-12-27, and 2026-02-04. Those of the 2009-09-02 appointment start on 2011-01-19, 2015-02-27, 2017-11-23, 2022-01-01, and 2026-02-09.

The good recurrences of the 2008-04-25 appointment that cover only a single day occur on 2009-09-07, 2012-06-03, 2013-10-16, 2016-07-12, 2019-04-08, 2020-08-20, 2023-05-17, and 2024-09-28. Those of the 2009-09-02 appointment occur on 2012-05-29, 2013-10-11, 2016-07-07, 2019-04-03, 2020-08-15, 2023-05-12, and 2024-09-23.

Screenshots/Screen recordings

Here is a screenshot of the recurrence of both appointments in February 2026. Each covers 2 days instead of the expected 1 day.

Additional information

My phone is in the Central European timezone (UTC+1 in winter, UTC+2 in summer). My phone is not rooted.

I think that the problem is related to the Daylight Savings status. Standard Time was in effect on the dates of the original appointments, and it looks like Daylight Savings Time is in effect on the dates of the bad, two-day recurrences. Perhaps the app stores the appointments not as just a date but as a 24-hour interval starting at midnight at the beginning of the given date in the timezone that was in effect at that time, and doesn't properly take into account the one-hour time shift when the recurrence falls in a period with a different timezone offset due to a Daylight Savings switch.

[sauraisg]

Hi, I've been having the same bug for a couple months now with recurring events but also with national days and holidays (that are auto generated). Some of these events are extended to 2 days instead of 1 (as initially configured). The weird thing is that in both cases they are defined as entire days and not on specific hours so I don't know if it's a problem of timezones and daylight saving times.