Post action way too soon

I have a .py script shich shall show the build number after build process finished (preferrable on success). I have added it as a post action in platformio.ini:

extra_scripts =

sadly it gets executed after printing the Dependency Graph, before the compiling starts. Is there any way to have it executed at the end or after the build process?

What action are you hooking onto?

i.e. are you using something like

Import("env", "projenv")

def after_build(source, target, env):
    # do some actions

env.AddPostAction("buildprog", after_build)