{
 "charged": false,
 "detail": "the signer key is not loaded; no envelope can be produced",
 "error": "signing_unavailable",
 "http_status": 503,
 "note": "when signing is unavailable the service returns 503 before any RPC read, no charge, no envelope; an unsigned envelope is never emitted",
 "reason_codes": [
  "signing_unavailable"
 ],
 "schema_version": "settle_v1"
}