Hammerspoon script enabling a Mac Shortcuts workflow when an external monitor gets connected

.hammerspoon [slash] init.lua

-- Mac Shortcuts workflow name
local workflowName = "Home Bluetooth"

hs.logger.defaultLogLevel = "info"
local log = hs.logger.new("DisplayWatcher", "info")

local function runWorkflowIfExternalDisplay()
  local hasExternal = false
  for _, screen in ipairs(hs.screen.allScreens()) do
    if screen:name() ~= "Built-in Retina Display" then
      hasExternal = true
      break
    end
  end

  if not hasExternal then
    return
  end

  log.i("External display detected. Running Shortcuts workflow in 5 seconds...")
  hs.timer.doAfter(5, function()
    log.i("Executing workflow...")
    hs.execute('shortcuts run "' .. workflowName .. '"')
  end)
end

hs.screen.watcher.new(function()
  runWorkflowIfExternalDisplay()
end):start()

log.i("Hammerspoon display watcher started.")

install-hammerspoon.sh

brew install hammerspoon

open /Applications/Hammerspoon.app

-- Consider enabling `Launch Hammerspoon at login` in app settings