What is the ruling on a wife leaving the apartment entrance after her husband says, "By divorce, you shall not leave," with the husband intending that she not go out into the street?

Since you swore to your wife, intending to prevent her from going out into the street, your oath is restricted by what you intended. You do not break your oath merely by her exiting the door, because intention in an oath specifies the general. Therefore, no divorce occurred when your wife exited the door and returned without going out into the street. As for your statement, "because by this action of hers, she has become divorced," if you intended by it to effect a divorce, then it has occurred. But if you intended by it to inform of the occurrence of divorce because you thought it had occurred by her exiting the door, then the preponderant opinion with us is that no divorce occurred in this case, because it is information based on a mistaken assumption. We caution you that the lawful oath is to swear by Allah the Almighty. As for swearing by divorce, it is among the oaths of the wicked, and it may lead to undesirable consequences.