When does a new GC holder lose H status?

[ParanoidAndroid]

While in AOS, an H visa holder essentially maintains dual status, which allows reentering the country w/out AP, if you have a valid H visa. This is a kind of 101 of immigration process and doesn't require any clarification.

But suppose the following situation. Primary i485 applicant gets a magic approval sms (POD is current). For some reason, the same sms doesn't come for dependant. How instanteneous is the loss of H status for primary applicant? is it the same second or the same day or there is some twilight timeframe? Or even a better question, how quickly it is reflected in computer system so that derivative H status gets lost as well? Suppose that H4 dependant is traveling to Canada at the time of i485 approval for the primary applicant. In case of immediate notification, will it be possible for dependant to get re-admitted to US using H visa, if attempting to cross the border on the same day? next day? To push it to the next level of complexity, what if dependant is using AVR process to get in from Canada? What does essentially define the loss of dual status - I know people receive several notifications - approval, COP, etc - so which of them triggers the loss of H status? Worst case, if not admitted under derivative H status, how to get into the country? All in all, how risky is to make a short term trip outside US on derivative H status without AP?

[Belle]

The primary loses H status when the AOS is approved. The derivative then should not enter on H4, but assuming reasonable timing (up to a few weeks), generally, it's not a problem. This is why lawyers recommend getting an AP even when you have a stamped H visa. Also, since a similar situation happens to H1 petitioners (AOS approved while abroad), it is assumed that this person may enter on H1 after a short absense from the US even after AOS approval. The point is for the absense to be short. Couple of weeks is fine. Couple of months after approval - not so much.

[tusharvk]

It may be for such cases where the primary gets 485 approval and dependent does not and travelling out of the US that AP is required to be had and timely renewed.

[JoeF]

A person is an LPR from the date of the I-485 approval.

Dependents presumably have their own I-485s pending, so they should have valid APs to prevent any potential problems when traveling.