> "Mark" offline? Why not just terminate it? And why do we care if build nodes come and go? These should be cattle, not pets. If they all die at once, that's bad. If they're cycling in and out, that's business as usual.

Given that they are for mobile builds, there might be some macOS nodes in there for iOS builds. These might be in-house machines they maintain -- or, if they use a cloud provider, there might be costs to just killing and spinning up nodes. For example, for EC2 Mac instances:

> EC2 Mac instances are available for purchase as Dedicated Hosts through On Demand and Savings Plans pricing models. Billing for EC2 Mac instances is per second with a 24-hour minimum allocation period to comply with the Apple macOS Software License Agreement.