archive-after.js

// label any email with archive-after/2-hours or archive-after/1-day (any number of days or hours) and it does!
// you can optionaly nest the labels eg `archive-after` and make `2-hours` inside the archive after - the script doesn't seem to care!

// Install steps
// create a new project here https://script.google.com/
// create a new file with this contents
// then create a trigger to run it every 10 minutes
// enjoy!

const LABEL_REGEX = /archive-after\/(\d+)-(day|hour)s?/
const HOUR = 1000 * 60 * 60

function archiveAfterLabels() {
  
  const labels = GmailApp.getUserLabels()

  const rules = []

  for (const label of labels) {
    const labelName = label.getName()
    const match = labelName.match(LABEL_REGEX)
    if (!match) {
      continue
    }
    const [, duration, period] = match
    let multiplier = 0
    switch (period) {
      case 'day': multiplier = 24; break;
      case 'hour': multiplier = 1; break;
      default: continue;
    }
    rules.push([label, Number(duration) * HOUR * multiplier])
  }

  console.log('detected rules', rules.map(([label, timeout]) => [label.getName(), timeout]))

  for (const [label, timeout] of rules) {
    const labelName = label.getName()
    const search = `label:${labelName} in:inbox `
    const threads = GmailApp.search(search, 0, 100)
    for (const thread of threads) {
      const threadTime = thread.getLastMessageDate().getTime()
      if (threadTime < (Date.now() - timeout)) {
        console.log('archiving and removing label', thread.getFirstMessageSubject(), labelName)
        thread.moveToArchive()
        thread.removeLabel(label)
      } else {
        console.log('skipping', thread.getFirstMessageSubject(), labelName, `Remaining time ${Math.floor((threadTime - (Date.now() - timeout)) / 1000)} seconds`)
      }
    }
  }
}