>Dropping a bomb is not an act of war because of the target itself. It is because to do it you have to violate the country's whole security system and cause damage to the country's real state, which is an act of war, whereas to invade a company's cluster of computers you don't have to compromise the country's whole cybernetwork.

I would counter that you don't need to violate all of the US's defense to bomb Hawaii and we all know how that was received. So yes, a state sending assets to go destroy some other state's property within the borders of said state is generally considered an act of war. That said, details matter a lot and these situations are basically handled on a case by case basis.

Deliberate attacks against a country’s economy would probably be handled on a case by case basis through diplomatic channels.

E.g. I’d argue that if China announced it would not repay its massive Treasury debts to the US, that would basically be an act of war even if no aggression was used, just due to the extreme destructive effects. And the reaction would be similarly upsetting, although not quite on the level of an unprovoked, large-scale military action.

But it quickly becomes a discussion of semantics at that point ;)