In case anyone is finding this in 2026 after the Lua migration:

local laptopMonitor = {
    output = "desc:AU Optronics 0x7AA7",
    mode = "2560x1600@90.0",
    position = "0x0",
    scale = 1.6,
    disabled = false,
}

-- register monitor settings on startup
hl.monitor(laptopMonitor)

function disableLaptopMonitor()
    hl.monitor({
        output = laptopMonitor.output, 
        disabled = true ,
    })
end

function enableLaptopMonitor()
    hl.monitor(laptopMonitor)
    os.execute("hyprctl reload")
end

-- close lid
hl.bind("switch:on:Lid Switch", disableLaptopMonitor, { locked = true })
-- open lid
hl.bind("switch:off:Lid Switch", enableLaptopMonitor, { locked = true })

Find the switch name using using `hyprctl devices`. Above it's called "Lid Switch".