by Sviatoslav Petrov
Full night screen mode.
When automatic screen brightness is off & less then 50%, this flow will invert screen color space*, & ask in pop-up window "Use Gray-scale?"(that switch colour space to gray-scale). Also system wallpaper will switch to night**.
IMPORTANT: before start flow, enter to Flowchart & setup custom wallpapers.
* For better look, switch all app themes to white;
** In Flowchart, left image node = night wallpaper, right image node = day wallpaper. For creating night version of wallpaper, for example, edit your image in Snapseed use Curves for invert color.