ability to set reviveContext while providing higher-level restoreSnapshot logic

[christophe-g]

I'll start with my use case:

I persist context that holds a (or multiple) firebase reference object. When context is restored, reviveContext loops through this complex Object (which holds refs to the Window object ...).

This is opening the door to more serious issues (see #5228).

I would like to have a way to act on reviveContext. For instance, skipping the recursivity when it reaches a firestore document reference:

  function reviveContext(
    contextPart: Record<string, unknown>,
    children: Record<string, AnyActorRef>
  ) {
    if (seen.has(contextPart)) {
      return;
    }
    seen.add(contextPart);
    for (const key in contextPart) {
      const value: unknown = contextPart[key];

      if (value && typeof value === 'object') {

// ADDED
        // if we have a Firestore Document or Collection, we need to skip it
        if ('firestore' in value && ('type' in value && value.type === 'document')) {
          contextPart[key] = value;
          continue;
        }
// END ADDED

        if ('xstate$$type' in value && value.xstate$$type === $$ACTOR_TYPE) {
          contextPart[key] = children[(value as any).id];
          continue;
        }
        reviveContext(value as typeof contextPart, children);
      }
    }
  }

  reviveContext(restoredSnapshot.context, children);

The problem is that it is not possible to pass on a restoreSnapshot higher-level logic method as most of the methods used there are not exported (createMachineSnapshot, getAllStateNodes, getStateNodes, ...). As I would need the same restoring logic (e.g. restoring snapshotChildren), I would need to call these.

Now back to the feature request :

1. is is possible to export all methods internally used in restoreSnapshot, or
2. provide a way to provide a user-defined reviveContext function while restoring state ?