sentry/static/app/views/alerts/rules/metric/utils/isCustomMetricField.tsx

import {getUseCaseFromMRI, parseField} from 'sentry/utils/metrics/mri';

export const isCustomMetricField = (aggregate: string): boolean => {
  const parsed = parseField(aggregate);
  return getUseCaseFromMRI(parsed?.mri) === 'custom';
};