Weight paint - how to make sharp edge falloff?

How to make edges in weight painting mode very sharp?
I tried using constant falloff or testing levels, but the soft falloff don’t go away.

That’s as far sharp as it gets, I’m guessing it’s just the weight color display. it needs to indicate somehow that 1 vert has the weight of 1, the other the weight of 0, so it’d fade the colors. You can change that in the preferences under editing, but that wont change the weights, those should be sharp using constant falloff.

weight