Incompatibility with com.oplus.calendar: "With sound" property lost during sync

[u07]

Android version and device/firmware type

Android 16, RealmeUI 7 (Realme GT7)

Steps to reproduce

• Connect a Yandex.Calendar account via DAVx⁵.
• Create a local event on the phone and make sure the "Sound" checkbox is ON.
• Trigger a sync.
• Check the event again — the sound toggle has been automatically switched OFF.

Alternatively, it works the other way around:

• In the calendar preferences (via browser), set a default notification (e.g., "30 min before via CalDAV").
• Create a new event on the server and sync it with the phone.
• Check the event on the phone: The 30-minute reminder is there, but the "sound" is OFF. So you won't get a proper alarm from com.oplus.calendar, except a standard push.

Actual result

All synced events are muted by default.

Expected result

The "With sound" state should be preserved. Ideally, it should be enabled by default if not specified, as silent notifications for calendar events aren't very helpful.

I suspect this "With sound" toggle might be a custom property of the Realme UI calendar app. It seems like davx5 might be overwriting this specific field.

[u07]

davx5-log.txt

[rfc2822]

Unfortunately I don't have Oppo Calendar available for testing. However the logs indicate that:

1. the calendar app doesn't provide the property property in a standardized or davx5-readable way (probablize it's only stored within the app). DAVx5 can't upload the property to the server.
2. Yandex, when it accepts the event, doesn't provide a result ETag (I have verified that with our Yandex test account). This means that the event, as soon as it's uploaded, will be downloaded again from the server because it could have changed again.
3. When downloading, DAVx5 updates the event and re-creates the reminders from the received iCalendar. I suspect that these causes the information in the oneplus calendar to be lost.

I can't however know it because it's neither documented nor testable …

[u07]

Oppo calendar is available in wild (the version may be older). Although what you're saying doesn't sound promising...

Calendar+(com.oplus.calendar)+[v.15.10.0].apk
https://disk.yandex.ru/d/fp80xMSGUY6jOg

Source:
https://4pda.to/forum/index.php?showtopic=1089800&view=findpost&p=137101387

DAVx5 updates the event and re-creates

Gosh, do you recreate all the events? Like, delete them and set again every time? The calendar should be mad about that, rebuilding it's database...Isn't it possible to compare events beforehand? What if it hasn't changed?