Limiting creation of too much data for invitees

[joepio]

Consider the following:

• User A invites B to append a resource somewhere (e.g. add one comment in a chat)
• B gives themselves write rights in the resource they append
• B can now, in theory, create an infinitely large tree of resources under this comment, completely unrelated to the root item.

User A should have some tools to prevent this. I'm not quite sure how this might work.

• If we constrain append right to only go one level deep, users can't do things like add an attachment to their comment.

Ideas are welcome!