PersistentServerRegistry class

A CRDTServerRegistry that keeps every document it serves on disk.

It holds the live CRDTDocuments and routes to them, the way any registry does. It never reads or writes storage by hand. Each document gets a CRDTDocumentPersistence, which follows CRDTDocument.events and writes down what each event reports. So a change applied here is stored, a snapshot replaces the one before it, and a prune drops exactly the changes it covered — all of it batched, and inside a CRDTDocumentStorage.transaction where the backend has one.

It works on any adapter, because it only ever sees the storage contract:

final registry = PersistentServerRegistry(
  backend: await CRDTHive.open(),
  compactAfter: 500,
);

Documents are opened lazily: a document costs nothing until something asks for it. Getting one back out of memory never happens on its own. Call releaseDocument when a room empties, or pass idleAfter and let the registry do it. With neither, a server holds every document it has ever been asked for.

Call close on shutdown. It flushes every open document.