I downloaded a Shabbat Alert app for my iPad, because i needed an alarm that would shut off after a few minutes. It worked fine (except that my iPad was muted), and it seemed to be quite halachic. In fact, perhaps it even went above and beyond.
Before it let me do anything, it made me "sign" an agreement that i wouldn't use the app on Shabbat.
Is there any halachic basis for requiring an agreement like this?