The way that the python environment is set up for scripts/entrypoints (by modifying sys.path with site.addsitedir) is not inherited with multiprocessing (when spawn is used)

[colonelpanic8]

The way that the python environment is set up for scripts/entrypoints (by modifying sys.path with site.addsitedir) is not inherited with multiprocessing (when spawn is used)

Basically, because the modification to sys.path only happen within the process, it does not seem that the child process properly inherits all of those modifications.

Looking in to a bit more, it may be that this is actually more of a nixpkgs issue than anything else, because this happens here:

https://github.com/NixOS/nixpkgs/blob/bd346e9f29610cbedaa56104174ff1e656efe521/pkgs/development/interpreters/python/wrap-python.nix#L39

but I do basically think that we need to properly wrap the binary or set something in the environment so that this works properly.

[adisbladis]

I've been creating a new fully featured editable implementation in NixOS/nixpkgs#339228.
I think the right way to go about this is how I'm implementing it in uv2nix: https://github.com/adisbladis/uv2nix/pull/8/files#diff-b0ed524beda0c5e24aaf8c9a4fb8fc81c4686041096ed006c52add697d9f29b1.

Basically: Add your leaf-package to the overlay created and override it to be editable. This takes all scripts & entrypoints into account.