The problem is with input[number] field. When i change value to invalid and uncheck checkbox field should reset value to last valid one and thus there should be no validation error. View value is changed back but validation value is still present.

See the demo: http://plnkr.co/edit/qIFxmVEXowSNGaBifV4T?p=preview

By digging some into angular, whole problem seems to be automatically added "badInputChecker" $parser. It checks element ValidityState without respect to new value and in consequence returns undefined to model.

Workaround could be before $setViewValue() to set new value for input and perform checkValidity():

  // Set new input value and do checkValidity() that updates input ValidityState
  var tmp = input.val();
  input.val(valid);
  input[0].checkValidity()
  input.val(tmp);
  // Do standard angular $setViewValue()
  inputCtrl.$setViewValue(valid);
  inputCtrl.$render();

Any ideas or plans how can this be solved in angularjs?

Cheers,
Edvinas