KB / Memory / tech-llm-gateway-quota-as-retryable
Quota errors may arrive as HTTP 400
Reseller budget errors buried in 400 should failover like 402/429
Some upstreams return budget_exceeded as HTTP 400. Classify as retryable/failover, not terminal client error.
Also: zero-byte full timeouts are terminal per backend per request — don't burn identical retries. See project-anyrouter.