What actually happens when you roll back an agent in production

Rolling back a bad code deploy is a solved problem. Rolling back a bad agent deploy is less obvious, because 'the agent' isn't just code — it's a prompt, a set of tools, a policy configuration, and often a fine-tuned model, all versioned together.

If you only version the prompt, you can end up in a state where the rolled-back prompt is now paired with a tool schema it was never tested against. The rollback looks successful and then fails in a new, confusing way.

Arclight checkpoints the full configuration bundle — prompt, tools, policy, and model reference — as a single version. Rolling back restores all four at once, which is what makes a one-click revert actually safe to hit under pressure.