How to cache, refresh, and invalidate carrier access tokens without creating an auth outage.
Carrier OAuth flows are usually simple client-credentials exchanges, but the operational risk is in the lifecycle. Cache the token centrally, refresh with an expiry buffer, and prevent every worker from refreshing at once. A single-flight refresh path plus token-expiry metrics turns auth from a hidden dependency into something you can observe and control.
When a token expires unexpectedly, treat the incident as both an auth failure and a traffic problem. Uncoordinated refresh storms can rate-limit the token endpoint and widen the outage.