Build snapshots with a message queue

Instead of periodically creating snapshots on a timer, create a new worker that consumes a message queue of new actions. When a new action comes in to the socket handler publish on to the queue. Only keep X amount of snapshots (per layer).

Possible issues and problems to solve:

• Keeping messages in order
• How to handle nack'ing messages?
• Multiple worker instances

The hope is that this can help alleviate anticipated performance and user experience issues with an undo feature.