Reasonable sleep over expectations

[EveSix]

What reasonable expectations do you put in place when your DC has a friend staying the night?
DC1(12) has a friend staying over. We have agreed lights out and good night at midnight as it's the holidays. They have form for talking really late and on previous occasions I've had to get quite firm as they've just kept eachother awake for ages. I don't want to go to bed before they're asleep as I know they'll chat until the early hours, and DC1 is terrible after a late night. I also don't want any online activity I'm not aware of; DC1 doesn't have access to their phone at night, but I can't really stipulate whether their friend does.
But DC's friend is not getting the message and is nattering away. I've been in and reminded them of what we all agreed, but no dice. Told them I will sit on the landing outside the room until it's quiet but it's not stopping them. Stupidly, it's not like I can actually do anything about it at ten past one in the morning; I can't exactly say "Mkay, grab your toothbrush, I'm taking you home, chatterbox!"
Am I expecting too much in terms of their ability to stick to an agreement, and is a midnight lights out too early for 12-year olds? Should I just let them crack on next time? Or would you not let there be a next time?

Leave them be and get to bed. They can have a long lie in morning.

Leave them be a go to bed.

Going forward let the parents and child know that phones are left in the kitchen/living room or whatever you normally do and include them in it. Every parent has been relieved that we don’t do phones overnight as sleepovers can be trouble (folks on here all post as if I’m weird when I say that but 5 of my 6 kids have gone through the sleepover stage and that’s always been the rule and only once did a parent object, but that turned out to be because their kid liked to tiktok sleeping mates on a sleepover abd parent found it funny)

I always just accepted that there would be very little sleep and cranky kids the next day, as did all the other parents. My DS is adamant that at some of the sleep overs at other places they didn't actually sleep at all.

We had loads of sleepovers when my son was little,practically ever weekend. We had a very firm no noise after midnight rule or you're going home. Sleepovers don't mean you get to keep the rest of the house up. No one minded as they were back often enough!

I would say probably just leave them to it. Unless you have plans for tomorrow which means they need sleep (though that in itself is probably a silly idea!). The other option is being very firm and saying it’s lights out/no more talking at time x. And if they don’t comply friend is taken home. I find it’s either completely free rein or very strict and stick to it. Any middle ground tends to not really work, especially if they are excited.

You can't sit on the landing outside! My 12yo would be mortified.
As long as they're not screaming/shouting, and just chatting, then leave them to it and go to bed

Our rule is don’t wake us up.
we make sure to have nothing else scheduled the next day

our tv has parental controls that mean they can’t get to anything too awful.

we take away everything else connected to the internet.

we haven’t had a sleepover in a while and at the time, the girls were at an age where we could didn’t have to worry about internet access via cell phone that wasn’t over wi-fi. They are just getting old enough that is becoming an issue and I’m not sure how we will handle that. I will probably discuss cell phone rules with other parents prior.. most of DD’s friends have pretty conservative parents with regards to cell phones. We use a night-time mode on our DD’s phone, so she would still be able to call our text us, but wouldn’t be able to browse online

Thank you for your replies.
DC1 has attended lots of sleepovers where no-one sleeps until sunrise, but they're always a wreck for days afterwards. DC1 is ND and tiredness seems to scramble processing and trigger massive anxiety.
I should have said, noise travels really well in our (tiny) house, so totally leaving them to it isn't an option -no one would get any sleep then. As a result, I'm quite clear about there needing to be a shut-up-time. It's really that, or nobody stays.
As it is, DC2 has just come to wake me up to complain that they're disturbed by a night light 'leaking' in from DC1's. So now we're awake despite DC1 & friend finally being asleep 😂.
I think I'm just a bit miffed that I stated a really clear boundary as a condition for the sleepover to go ahead and it was ignored.

Your child is in secondary school, I bet they're mortified when their friend tells their other friends that mum stood on the landing until we went to sleep. It's a sleepover, they're going to be up talking all night. It's a one off. If you're so bothered about your DC's sleep schedule, you shouldn't have allowed one!

Well, if I parented according to what would make DC1 feel mortified, I wouldn't dare do anything ever. Seems to be the age for it.
I'm pretty laid back about most things and definitely pick my battles, but I do expect to be able to negotiate and for deals to be stuck to if we've all agreed.

Thank you all again for taking the time to share your thoughts.