Versions
Versions in Agent host: every save is immutable, deploy activates one and pushes it to the agent, roll back activates an earlier one.
Every save creates a version that never changes. Deploy activates a version and pushes it to the agent. Roll back activates an earlier one. You can see what each version said.
You can also pause and resume an agent, and archive one you no longer need; archived agents do not count against your plan.