Errors

{
  "error": {
    "code": "error_code",
    "message": "Human-readable message",
    "details": []
  }
}

{
  "error": {
    "code": "validation_error",
    "message": "Request validation failed",
    "details": [
      {
        "field": "context.billable_customer_id",
        "code": "required",
        "message": "billable_customer_id is required"
      }
    ]
  }
}

{
  "error": {
    "code": "unauthorized",
    "message": "Invalid or missing API key"
  }
}

{
  "status": "partial_success",
  "events_queued": 1,
  "events_failed": 1,
  "results": [
    { "transaction_index": 0, "message_id": "abc123" },
    { "transaction_index": 1, "error": "billable_customer_id is required" }
  ]
}

{
  "error": {
    "code": "internal_error",
    "message": "An unexpected error occurred"
  }
}