Help with Editable Install

[squat]

I've had a lot of success so far with this library in conjunction with both buildPythonApplication and buildPythonModule, however I'm a bit stuck on how to get an editable install of a local package with either of these two functions.

My context is that we use a monorepo at work and have a couple of helper CLIs written in Python to aid in various development and SRE tasks. These tools have to stay up-to-date with the rest of the source code otherwise there are no guarantees that anything will work.

I have a pretty basic flake.nix that defines a devShell that installs these CLIs from source in the monorepo using pyproject.nix so that engineers can have a consistent environment, but I can't figure out how to get editable installs working. I've read the some threads on the NixOS Discourse about setting PYTHONPATH [0] or how the presence of a setup.py should magically make things work [1] but haven't had any luck yet.

Do you have any suggestions? Maybe a (flake-based) venv workflow is more suited for this challenge?

[0] https://discourse.nixos.org/t/nix-shell-buildpythonpackage-pyproject-toml-does-not-seem-to-give-editable-installation-correctly/31180/13
[1] https://discourse.nixos.org/t/installing-a-python-package-in-development-mode-in-nix-shell/18475