Currently, there are two modes for the couploer track kit: sticky mode and unlink mode. An unstick mode would help in case of shunting.

I don't understand: Exactly what do you want here and how should it differ from the existing unlink mode? Don't make a vague issue and then label it as a "good first issue" as it will create incentives for messy PRs as the issue wasn't defined well in the first place.

you know rc adds a cart ability to allow carts to link when they collide. the new mode means to remove that ability.

Basically what Liach was saying in a somewhat more easily understandable form (no offense Liach) was unstick mode wouldn't function like unlink, but rather remove the ability from carts to link together when colliding via sticky mode.

This should be handled already by an unpowered auto-coupler. If it isn't, then it's an oversight and should be looked into.

Isn't that the same as unlink?

I'm guessing what Liach wants is something that won't unlink, but will unsticky carts.

This is extremely easy to work on.

Resolved in c7487b5