There's this woman in one of the rooms near the north end of the bridge who asks you to get rid of the rat swarm so she can leave. How do you do it? I've tried distracting them with a corpse but the woman wouldn't leave. Then I shot at them with incendiary bolts until the rest of the swarm slunk away. That did it, but I used up eight incendiary bolts for that. I don't really need incendiary bolts in this playthrough, so I didn't mind, but I wonder if there's a more efficient solution.

i crouch in a safe spot and hit them with my blade until enough are dead that they run away

Feed them a corpse and while they are chowing down, hit them with something lethal. I like to draw the swarm far away from the woman and blow them up with a grenade.

I got rid of the swarm, but she didn't leave. Is there some trick to it?

you have to interact with her to "trigger" her departure.
It's a bit weird since every other mini-missions in the game is automatically validated

And sometimes it just glitches out and she won't leave. Happened to me the very first time I "helped" her. Tried talking to her after all the rats were gone, she just sat there.

To punish her ingratitude, I summoned my own swarm right next to her.

I drew them together with a corpse and hit them with a grenade.

Ah, a grenade. Never thought of that. I don't even know if I'm carrying one at the moment. But doesn't that make an unholy amount of noise? The kind you want to avoid if you play stealthy? Not that there are any conscious guards left in that place...

Yes, it does get you detected but by the time I get back up top the guards have gone back about their business. You could also try a spring razor, if you're quick about setting it up and getting out of the way.

That's what happened to me - she just went unresponsive and wouldn't react when I tried to interact with her, so I just left her there.

Tossed a corpse at them, waited for them to congregate together, froze time, ran up to them and applied sword liberally.
Then when time unfroze.... rat chunks flying everywhere!

Talked to girl, she thanked me and left.

Being the total cheapskate that I am, I went back to the wall of light power station and picked up the whale oil canister I'd taken out of it. Carried it over to the building, used a dead body to make them get together and threw it at them. Not wasting a grenade on rats

You can also use Windblast on them.

Stopped time, possessed the woman and walked her out to the second floor.