This seems to have some parallels with durable execution engines like Temporal which have deterministic concepts of time and use event sourcing or snapshotting

This seems to have some parallels with durable execution engines like Temporal which have deterministic concepts of time and use event sourcing or snapshotting to ensure the past remains the past but allow you to evolve code for the future (disclaimer I work at Temporal). Have you considered this approach to apply to more than time? There is all sorts of conditional-based divergence code may take beyond time.