curl --fail-with-body -sS "$HARNESSROUTER_BASE_URL/v1/responses" \
  -H "Authorization: Bearer ${HARNESSROUTER_API_KEY:?}" \
  -H "content-type: application/json" \
  -d '{
    "input": "Reply with exactly: it works.",
    "metadata": {"harness_id": "hermes"},
    "model": "gpt-5.4-mini",
    "stream": false
  }'