Embodiments are directed to executing a workflow using a virtualized clock and to ensuring idempotency and correctness among workflow processes. In one scenario, a computer system a computer system determines that a workflow session has been initialized. The workflow session runs as a set of episodes, where each episode includes one or more pulses of work that are performed when triggered by an event. Each workflow session is processed according to a virtualized clock that keeps a virtual session time for the workflow session. The computer system receives an event that includes an indication of the time the event was generated, and then accesses the received event to determine which pulses of work are to be performed as part of a workflow session episode. The computer system then executes the determined pulses of work according to the virtual session time indicated by the virtualized clock.