OpenRouter outage analysis: cold cache overwhelmed the database

A teardown of OpenRouter's February outages found that when the cache stopped serving API-key lookups, the database absorbed the load and returned 401 "User not found" instead of 503. The first outage coincided with a DoS attack, while a repeat without one pointed to a cold cache and retry storm.

• Cache failure pushed lookups onto the database that normally absorbs them
• Infrastructure failures surfaced to clients as 401 rather than 503
• First outage overlapped with a DoS attack; the repeat confirmed the cause
• Recommended fixes include circuit breakers and controlled cache repopulation