Here's a minor mystery. Maybe someone can shed some light:
I force-stopped the Reddit app and nuked its cache and storage space. When I restarted it and tapped on "Log in", lo and behold, it had remembered my account.
How does that happen? Is there some hidden storage space available to apps that can never be erased? Can apps write stuff in their installation directory to survive a complete cleanup?
I also looked around in the filesystem in an adb shell, to see if it had written a file somewhere, but I couldn't find anything.
In the end, I uninstalled and reinstalled the APK and it finally forgot my old account.
I've never seen an app do that. If clearing the cache and storage space doesn't guarantee that an app is fully reset, I'm gonna start uninstalling/reinstalling them as well.
Are you sure the app remembered it and it wasn't auto filled by Android, the system will remember usernames and passwords separately from the app data and auto fill
No I'm not sure. I'm just telling it like I saw it. It was creepy.
I didn't know Android did that. I was under the impression that whatever I entered in an app stayed in the app - unless I deliberately copied it in the clipboard of course. I have never seen Android autofill anything.
But then, if I uninstalled the APK and immediately reinstalled the same APK, why didn't Android autofill my account name again after I reinstalled it?