Yes, we are assuming a log that picks linearizability at the cost of availability under partitions. Like most logs do, including Kafka, Pulsar, RedPanda, etc.

The application state is defined by the log here, and the log drives retries/recovery, so it doesn't much matter if the process that executes the app code splits off. The log would hydrate another one.

Also the one log is at the granularity of a single key or handler execution. More of a logical log, than a physical log or even partition.

In Restate, we implement a logical log-per-key, backed by a partitioned physical log.