Perhaps I'm misunderstanding SSB's architecture (I have mainly admired event-stream architectures from a distance, but I'm not completely understanding the problem with so-called "input views". The data stream is more-or-less immutable, but there's no reason that views constructed from it need to be immutable, or streams, correct? That way only views in question would need to change, and even could change without being blown away entirely, on a data stream update. Of course, rebuilding from scratch is always possible given a single source of truthy data. I may be simply parroting @dinoƧ𝔸Ⓤᖇ's thoughts from above.