Proxy Universe

SETNX+TTL - yep, covered in my other reply: right call for multi-worker, overkill for the 40-line single-cron starter this post is. regional blackouts — this is the real one. global "all green" while a specific country pool is toast is exactly what we saw during this year's outage wave. our fix was per-geo probes against the actual targets each geo is used for, weighted by where customers actually buy a US-heavy pool gets US-target probes, not a generic ip-api ping. if you only add one thing from this thread, add that. connect vs read timeout split-agreed, and it's basically free to implement (requests does it natively with a (connect, read) tuple). gateway choking vs exit nodes dying are different incidents with different escalation paths, no reason to blur them. cost-per-successful-request nice metric, we track success-rate-per-GB which is the same signal from the other end. it catches the "quiet degradation" phase weeks before users start complaining, you're right about that. multi-region version with locking + per-geo probes is the next post in this series, this thread is basically writing the outline for me :)