A process starts a multi-step job. Step 1 validates the customer. Step 2 creates an internal record. Step 3 moves money, changes a subscription, sends an irreversible request to a partner, or does whatever your business considers serious. Then the process dies.

Not politely.

The container gets killed. The deploy rolls. The host disappears. The worker restarts halfway through the thing it was doing.

Now the question is simple and horrible:

What happens when it runs again?