Do you have examples of times you've had to dig into the nix language like that, at least at a high level?

Just curious. I haven't run into anything like that myself.

Using nix for three months now, the main "pain" I run into is that I want app config files to remain writable by the app, but home-manager ethos is understandably against that -- and this is what you want on servers.

So I've had to vibe-code my own HM module for claude code, keepassxc, cursor, etc. and use activation to merge my nix settings into those files if they exist. That way when I rebuild, my nix config can assert a subset of the config I care about without locking the app out of writing to config -- and this makes more sense for personal desktop computing.

Though I put pain in quotes because it's still 10x better than what I was doing before, and an LLM can do it just fine.