post/changed is called for both X->SUCCESS, or SUCCESS->X.
X being typically failure or unstable.
As a user, I would like to have a very straightforward way to express that I'm only interested in the X->SUCCESS direction, because actually the SUCCESS->X is already covered by post/unstable or post/failure blocks.
My use case is the following: I want to send an email for failures, unstable, and back to success. For the reason explained above, I don't want to send a notification when the status changes from success to something else, because then I would send two notifications instead for one actual event. And it would lower the signal/noise ratio.
I think it could be fullfilled like: