I have got a theory in my mind, need to get it out.
This is our Ukraine moment. Don't get surprised if a complex international conspiracy (USA and China on the same side) is at play.
IMO, Modi did not anticipate such arrogance/persistence from Pakistan, he totally miscalculated the Pakistani response. He planned it out more like a repeat of the "Surgical Strike" when both sides claimed victory and went on their separate ways. Only at a bigger scale, with publicly visible explosions.
This time, Pakistan wants to extract an hefty price so as to stop India from repeating such incursions in future. Also, some external actor is feeding Pakistan's war machine, just like Ukraine. The goal is to have a prolonged low-intensity conflict in this region.
This time, our national strength and will is going to get tested. If we win it decisively, we will establish ourselves as the undisputed hegemon in the region.