Client sided code

Most likely similar to datapacks, but for client side, With obvious security. You can detect "keypresses" or make custom movement. it would be useful for quite alot of servers. Again, its like datapacks, so its harmless. But it can send data back to the server. or set a client sided block. It would remove lag from aload of servers with such things. and would allow more things, like keybinds.