Live modeling is the ability to edit an executable model at run-time, and to subsequently continue the execution instead of having to restart it. Few modeling frameworks support this feature. Much of the research concerning live modeling attempts to bring “liveness” to existing modeling languages and environments, which is a complex, and often ad hoc endeavor. We instead argue to build modeling environments on an operation-based versioning foundation, to not only record edit operations, but also execution steps on an explicit run-time model. This reduces the complexity of patching the run-time state with edit operations to a simple merge-operation, while getting powerful features such as collaborative editing and debugging “for free.”