(Let's Encrypt engineer) Token bucket is a good idea, and I agree that it would make the user experience of hitting rate limits less onerous. We implemented sl

(Let's Encrypt engineer) Token bucket is a good idea, and I agree that it would make the user experience of hitting rate limits less onerous. We implemented sliding windows because they were straightforward to implement based on our long-term database state. I'll do some thinking about whether we can emulate a token bucket style on top of that without having to add another source of truth for rate limit information.