These covert communications are reminding me of a short story I read a few decades ago but haven't been able to track back down. I thought it was a Charles Stross story in the _Toast_ collection, but I re-read it and it isn't there.

In the story some University students take part in a trial that involves a brain scan and then them spending the rest of the day answering a customer support message. They can spend the whole day working on researching and writing a really good customer support reply to a user request. While doing this they notice something odd and realize through some sort of back-channel that this isn't the first time they've spent the day writing a customer support message; they are stuck in a simulation.

I'd really love to go back and re-read it, but I've not been able to find it again.

In _Toast_ is another story that's also relevant: A fairly innocuous news story pops up and our hero calls his partner at work to tell them that it's time to get their go bag and get off planet. This news story indicates the Earth is in the beginning stages of reaching an AI singularity, and this isn't the first time our hero has gone through this on a planet.