Sync is triggered when leaving the study screen

[ZornHadNoChoice]

Checked for duplicates?

• This issue is not a duplicate

Does it also happen in the desktop version?

• This bug does not occur in the latest version of Anki Desktop

What are the steps to reproduce this bug?

Study for at least 10 minutes then leave the study screen. A sync is triggered.

This happens in both the old and new study screens.

I think it also happens outside the study screen, for example by putting the app in the background for a second.

This didn't happen in v2.22.3.

Expected behaviour

"Sync automatically on app start/exit if the last sync was more than 10 minutes ago."

Debug info

AnkiDroid Version = 2.23.0 (4f768aa0be34e254d65fd4ebe19781b84e8efc37)  
Backend Version = 0.1.62-anki25.09.2 (25.09.2 3890e12c9e48c028c3f12aa58cb64bd9f8895e30)  
Android Version = 13 (SDK 33)  
ProductFlavor = play  
Device Info = Xiaomi | POCO | mondrian | mondrian_global | 23013PC75G | qcom  
Webview User Agent = Mozilla/5.0 (Linux; Android 13; 23013PC75G Build/TKQ1.220905.001; wv) AppleWebKit/537.36 (KHTML, like Gecko) Version/4.0 Chrome/143.0.7499.115 Mobile Safari/537.36  
ACRA UUID = 3792582f-98ac-430e-ae42-4ace0156bf29  
FSRS = 5.1.0 (Enabled: true)  
Crash Reports Enabled = true

(Optional) Anything else you want to share?

No response

Research

• I have checked the manual and the FAQ and could not find a solution to my issue
• (Optional) I have confirmed the issue is not resolved in the latest alpha release (instructions)

[david-allison]

"Sync automatically on app start/exit if the last sync was more than 10 minutes ago."

We should discuss the UX we want from automatic synchronization. I do like the way that it is, just to be sure I don't lose anything when done for the day, but it's likely frustrating with multiple active decks

[ZornHadNoChoice]

I should note that you lose the undo stack if you accidentally return to the deck screen, with this bug.

[Sandesh282]

I was able to reproduce this on the latest stable. After studying for some time, simply navigating away from the study screen or briefly backgrounding the app reliably triggers a sync, even when the last sync was recent. This matches the report and does not seem intentional given the documented behavior of syncing only if the last sync exceeds the time threshold.
From a quick investigation, this feels like a lifecycle-related trigger rather than an explicit user action. It looks like a sync may be initiated from a pause or stop path that is shared by normal navigation and actual app exit, which would explain why leaving the study screen clears undo state and causes an unexpected sync. I have not started a fix yet, but I wanted to note this in case it helps narrow down where the trigger is coming from, and I am happy to dig further.