Load balance right when we have higher guard rotation periods
Here's our plan:
- Directory authorities need to track how much of the past n months each relay was around and had the Guard flag.
- They vote a percentage for each relay in their vote, and the consensus has a new keyword on the w line so clients can learn how Guardy each relay has been.
- Clients change their load balancing algorithm to consider how Guardy you've been, rather than just treating Guard status as binary (#8453 (moved)).
- Raise the guard rotation period a lot (#8240 (moved)).