Thank you for proofreading the code and your words of encouragement :) ! Here is a new version that shows, in real time, the reverse-bag graph with the build and install status color coded into the nodes (node's border means building, node background means installing). A the end, the resulting graph looks like the attached image. It makes the failure of Jupyter hard to ignore (and also reveals a failure of python-iml that went undetected as of yet). The fact that you can see it in real time is really cool. As soon as you see red, you can rummage through the logs (error logs are copied in a subdir for conveniance) and start fixing the problem(s). I still haven't fixed jupyter yet. I'll work on it on monday. With the help of this tool it should be quite easy :) To use the script, just edit it to target the packages you are meddling with, and run. Give an optional first argument pointing to where you want the images saved (otherwise they are destroyed and the end of the script). It even makes an animated gif (not attached because of its humongous size). Completely useless, but it gives you something nice to show when somebody comes to visit your lab ;) I would love for this tool to become a subcommand of guix. I'm not sure about the name. 'before-submit' is clear enough, and I can't think of any good reasons why not, but I feel we can do better. Something to do with "monitor", "watch", "making sure", "real-time". I don't know yet. Naming truly is one of the hardest things in computer science ;-) For the time being, gpwc stands for the Guix Package Writer Companion. I could give a shot at reimplementing the tool in guile, but my guix-fu is not strong enough yet. I'll keep using this quick and dirty bash version until I feel confident enough. Cheers, Edouard.