Never heard of durable execution until now, but I've wondered about it. When I write backend code, I have to keep asking myself "what happens if the server goes down during this line of code?" This is often an issue in the middle of a customer order, like the example here. I end up relying on the database for very many tiny little things, like recording the fact that the user initiated an order before I start to process it.

But how fast is this? IIRC each little insert in my DB was taking like 5ms, which would add up quickly if I were to spam it everywhere; I assume durable execution layers are better optimized for that. Do they really only snapshot before and after async JS calls, treating all other lines as hermetic and thus able to be rerun?