hirelings and death

If I understand, in the rules hirelings are treated  like animate objects. They give bonuses to their users: + damage, + armor, + DRM when rolling for moves and so on...

They do not need equipment and HP because everything about them is virtual and they act via standardized actions.

but...
could they possibly die if fiction calls for their death?
could they possibly die during a bloody fight after a few "man-at-arm" moves resulting in a  "they take the brunt" effect? (they did not flee before because they passed one or more  loyalty check).
I believe the hireling's death - although not mentioned in the rules - is not prohibited.

Besides some evil Character could also kill them during the night to avoid  the payment for the job, or just to steal their swords (or any hand weapon they could have).
 
Is it all above possible, legal, doable, and in the spirit of the game or hirelings are immortal according the rules as they are written ?
thanks

As a hard-and-fast rule, if the fiction calls for something, it happens. That's how Dungeon World works. Sometimes that fiction triggers a move, and that's when the rules come into play. So yes, Hirelings could be killed by taking the brunt of an effect, in a fight with another NPC, or due to any number of mishaps.

When I run hirelings, I will be making a note of how many hitpoints they have. However, this will only come up if they take damage that a PC rolls (careful with that fireball, Greta...). The rest of the time, if they get hurt, they suffer effects according to the fiction. Sometimes the appropriate effect is death.

hirelings are (also) a player's resource, so as such, they are vulnerable to the gm's move "use up their resources". You make this move as hard as the rules allow it (so is a soft move unless you have a golden opportunity - that is, a player rolls a 6- on a move involving the hireling or the party deliberately ignores a threat menacing the hireling).

All of this to say that killing a hireling is just using up their resources, very hard.

hirelings are (also) a player's resource, so as such, they are vulnerable to the gm's move "use up their resources". You make this move as hard as the rules allow it (so is a soft move unless you have a golden opportunity - that is, a player rolls a 6- on a move involving the hireling or the party deliberately ignores a threat menacing the hireling).

All of this to say that killing a hireling is just using up their resources, very hard.

I hadn't drawn the connection to "Use Up Their Resources", that's the perfect way of looking at hirelings from a mechanical point of view.

Thanks!