I forked a live AI agent three ways, and every copy came up with its web server already running

The expensive part of working with a coding agent is rarely the last step. It is all the steps before it: the exploring, the false starts, the files it wrote and rewrote until the thing finally worked. Once an agent has got somewhere good, the state it is in is worth more than any individual output, and the uncomfortable truth is that you usually cannot get back to it. Run the same prompt again and you get something else. DigitalOcean's Managed Agents runs each session in its own microVM and lets you checkpoint that whole machine, fork it, and roll it back.