* Specifically, ztunnel should be able to send a request to the control plane to answer "I got a request to send traffic to 1.1.1.1, what is 1.1.1.1?"
  * While this is not needed for small scales, this is important for the long tail of massive clusters (think 1 million endpoints), where the entire set of endpoints cannot reasonably be replicated to each ztunnel.
* It should not be client-specific.

#### Optimizations

A naive implementation would simply regenerate all resources, of all subscribed types, for each client, on any configuration change. However, this scales poorly. As a result, we have many levels of optimizations to avoid doing this work.