I've found reliable persistence on the backend irritating with yjs. Seems like the official path is to fork their example library and edit it. (The example is insufficient because, for example, it will silently eat data if the onchange webhook fails).
yrs initially looks tempting but it's unsound at it's core. (The plan is to port the API directly from JS, use unsafe to silence the borrow checker, then gradually fix specific instances of undefined behavior if they cause actual real world issues.[1] I don't this this is an approach that can work. That's a shame because a lot of impressive work has gone into yrs.)
[1]: https://github.com/y-crdt/y-crdt/issues/233