What this gives you
When this is on, contacts saved in PixWork are written out to the phone’s own contact book.
Useful for seeing a caller’s name on an incoming call, or picking someone quickly from a messaging app like WhatsApp. Scan a card once and that person stops being an unknown number.
Only contacts that have a phone number are written out. A contact with no number is skipped.
One way, from PixWork to the phone
This is a one-way write-out from PixWork into the phone’s contact book. Edits or additions made in the phone’s own contacts app do not come back into PixWork.
The setting is labelled "Automatic sync to the OS contact book" in the app, but it behaves as described above — a write-out only, not a two-way sync.
A failed write-out does not undo the save on the device. By design, a failure here does not stop or roll back the save inside the app.
Supported platforms, and where the entries land
OS contact export works on both iOS and Android. "Automatic sync to the OS contact book" in Settings is the same one setting on either platform, and switching it off stops the write-out. The write-out runs on a best-effort basis each time a contact is saved, edited, or merged after a duplicate check.
Only the container they land in differs. On Android, PixWork creates a dedicated account of its own and writes only underneath it. On iOS, PixWork creates a group named "PixWork" in the phone’s contacts app and puts the exported entries in it.
Either way the entries stay distinguishable from the contacts that were already on the phone. On Android, pick "PixWork" in the accounts view of the contacts app to see just the exported ones. On an iPhone, do the same from the groups view.
Nothing this feature does differs by platform. Creating and updating by phone number, and checking and requesting permission, behave the same on both. There is one toggle, and it is there on an iPhone too.
What happens on deletion
Deleting a contact inside the app also removes it from the OS contact book, if it had been written out there and a phone number is stored.
Setting a row’s Status to Deleted in the sheet marks that contact deleted inside PixWork, so it drops out of the list. It is not removed from the phone’s address book.