Yeah, “by design” points at the deliberate nature of the action. ie. it’s not an accident.

It could be for good or bad intent, makes no difference.

The example I use in my book to demonstrate this is:

imagine you are sleeping and wake to find yourself handcuffed to the bed.

It doesn’t matter if was a playful partner or a malicious intruder, you know with absolute certainty that that act of handcuffing your was not an accident.

It’s “by design”