503 — Upstream unavailable

{
  "error": {
    "message": "Upstream provider unavailable: anthropic (gateway 503)",
    "type": "upstream_error",
    "provider": "anthropic",
    "upstream_status": 503
  }
}

What HiWay did

HiWay tried the routed provider and got an error back. It does not retry automatically against a different provider, because that would change the model and therefore the behavior — and most of our customers depend on deterministic routing. The decision to fail over is yours.

How to build failover

• Catch the 503 in your client code.
• Retry the same request with a pinned alternative: e.g. if the routed tier was standard → claude, pin openai:gpt-4o-mini and resend.
• Log both attempts so you can see the failover rate in your observability.