How do Base NPCs deal melee damage?

When working with Nextbots and bullseyes, i notice that Built-in Melee NPCs, such as Zombies, and Metrocops with Stunsticks don’t deal damage to my bot when they melee, even though thier animation plays.

Obviously Melee isn’t a “enemy:TakeDamage()” type ordeal, and it can’t be the “delayed hitscan” system i see elsewhere as well, because, if i understand it correctly, it would be akin to firing an invisible bullet when the melee animation plays, yet no damage is done, and my bots can take damage from regular bullets just fine.
So how exactly does their system work, if anyone knows?

This is something I’ve been wondering about for a while, and i can’t find the answer anywhere.