KeepsNothing

This backend keeps nothing across a process exit, and store is the fresh, empty store a restarted process would get — InMemoryDurableStore, or any other backend whose own KDoc says it is not crash-safe.

The honest arm, and it still asserts something: a fresh handle must read empty, so a restart returning the store it was given fails, and so does a backend that genuinely persists but declared this arm. What it cannot detect — stated here rather than left implied — is anything at all about durability. There is no medium for a write to fail to reach, so the obligation the DurableStore contract is arranged around is unreachable on this arm by construction. That is why the obligation lives in a TCK the durable backends also run.