Rebuilding projections is one of the more complicated subjects in event sourcing. EventSauce takes an uncommon approach to tackle this problem: it does not tackle the problem.
Generic rebuild tooling is very complex and imposes some additional constraints. Even then generic tooling will probably cover about 80% of the use-cases.
The way that EventSauce is designed allows for very easy extension.
Implementing your own
done in a matter of minutes. Keeping this interface simple was a very
important decision. It means you’re able to take full control of it
when (and if) needed.