What is the ruling regarding someone who enters Makkah not in a state of ihram with the intention of Hajj, then makes the intention for Hajj after entering, and what are the consequential rulings such as ihram, tawaf al-qudum, and cutting hair and trimming nails?

First: You must return to the Miqat and enter into ihram from there if you have passed it intending to perform the ritual. If you did not do so and entered into ihram from Makkah, then you must offer a sacrifice (dam) to be distributed among the poor of the Haram.

Second: The Tawaf of Arrival (Tawaf al-Qudum) is a Sunnah according to the majority of scholars, and obligatory according to the Malikis. The Tawaf of Arrival is waived for anyone who enters into ihram from Makkah. However, if you perform it as a precautionary measure, that is better. According to the Malikis, its obligation is not waived for someone who passed the Miqat and entered into ihram from the Haram.

Third: You are not required to refrain from cutting nails, hair, or skin before entering into ihram unless you intend to offer a sacrifice while performing Hajj, in which case you should refrain from these from the first of Dhul-Hijjah.