Battery, power mode and the screen lock
Battery
upower -i /org/freedesktop/UPower/devices/DisplayDevice # percentage, state, time to empty / full
Tier: observe. power supply: no or no percentage: the computer has no battery.
Power mode
powerprofilesctl list # the modes this computer offers (performance needs hardware support)
powerprofilesctl get
powerprofilesctl set power-saver # or balanced, performance
Tier: reversible. Undo: set the previous mode, read first with get.
Lock the screen
slate-lock
Tier: reversible (the person unlocks it with their password). While the screen is locked, the desktop tools refuse keyboard and pointer input: reading and element actions still work. Never type into the lock screen.
When the screen locks and turns off
~/.config/slate/idle.json holds {"lock_after": SECONDS, "screen_off_after": SECONDS} (0: never; defaults 600 and 900). Counted from the person's last input; what the agent does does not count. After writing it: systemctl --user restart slate-idle. The screen also locks before the computer sleeps. Settings, Power shows the same.
Tier: reversible. Undo: write the previous values back.
Verify
powerprofilesctl get prints the new mode; systemctl --user status slate-idle shows the swayidle command line with the new timeouts.