/**
 * Convert a polling interval in seconds into a cron expression.
 * Pure and side-effect free so it can be unit-tested without touching the DB.
 *  - < 60s            → every minute ("* * * * *")
 *  - < 60 minutes     → every N minutes ("*\/15 * * * *")
 *  - otherwise        → every N hours ("0 *\/6 * * *")
 */
export function secondsToCron(seconds: number): string {
  if (seconds < 60) return '* * * * *'
  const minutes = Math.round(seconds / 60)
  if (minutes < 60) return `*/${minutes} * * * *`
  const hours = Math.round(minutes / 60)
  return `0 */${hours} * * *`
}