The em-dash that broke the server

Bad news for developers who let AI agents write configuration files. There's a whole class of bug waiting for you which will cost you a day. They're entirely invisible until some script chokes on it harder than Team USA. I was building out infrastructure-as-code for a small fleet of servers following the usual pattern of baking a machine image and letting each new server configure itself on first boot from a cloud-init script. The agent wrote the cloud-init file, I skimmed it, it looked pretty good and I booted the server expecting the server to be ready for primetime. But the script never ran and it came up as a bare Ubuntu box, every trace of setup scrubbed clean like a red card that happened but also never happened. None of the setup ran, leaving me in that unenviable position of debugging agent work. Shudder. These are the worst kind of failures because they're quiet and even (correctly) confirmed by cloud-init status which said done even though it had done less work than the…