All You Need Are Timeouts

enforce_break.sh

#!/bin/bash

echo "----- $(date) -----"

current_hour=$(date +"%H")
current_minute=$(date +"%M")
hour_int=$((10#$current_hour))
minute_int=$((10#$current_minute))

if (( hour_int % 4 == 0 )); then
  break_minutes=15
elif (( hour_int % 2 == 0 )); then
  break_minutes=10
else
  break_minutes=5
fi

echo "Current hour: $hour_int, current minute: $minute_int"
echo "Break length this hour: $break_minutes minutes"

if (( minute_int < break_minutes )); then
  echo "Status: INSIDE break period"

  loggedInUser=$(stat -f "%Su" /dev/console)
  loggedInUID=$(id -u "$loggedInUser")
  loginwindow_pid=$(pgrep -nx -u "$loggedInUser" loginwindow)

  echo "Launching screen saver as user $loggedInUser (UID $loggedInUID), loginwindow PID: $loginwindow_pid"

  if [[ -n "$loginwindow_pid" ]]; then
    echo "Locking screen using pmset..."
    
    # Use su to run pmset as the actual user - this works reliably
    if su - "$loggedInUser" -c "pmset displaysleepnow" 2>/dev/null; then
      echo "Display locked successfully"
    else
      echo "Failed to lock screen - pmset error"
    fi
  else
    echo "ERROR: No loginwindow process found for $loggedInUser"
  fi
else
  echo "Status: OUTSIDE break period"
fi

sudo-cron.plist

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN"
 "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
<plist version="1.0">
  <dict>
    <key>Label</key>
    <string>com.local.enforcebreak</string>

    <key>ProgramArguments</key>
    <array>
      <string>/usr/local/bin/enforce_break.sh</string>
      <string>runAsUser</string>
    </array>

    <key>StartInterval</key>
    <integer>30</integer>

    <key>RunAtLoad</key>
    <true/>

    <key>StandardOutPath</key>
    <string>/tmp/enforcebreak.log</string>
    <key>StandardErrorPath</key>
    <string>/tmp/enforcebreak.err</string>
  </dict>
</plist>