This mod introduces a new state for players: in-combat. 

Players go into the in-combat state when attacking something or taking damage. While in combat, any healing is prohibited. The effect will fall off after a while, indicated by the icon on the middle right of the screen. 

The duration of the effect can be configured in noincombathealing.json (default 0.5 hours of ingame time, which at default settings is 60 real-life seconds)