[bergkvist]

My use case here is not using pkgs.fetchgit etc - but rather when developing a package locally and rebuilding it.

Let's say I'm working on a huge monorepo locally, with GBs of code and data in it, most of which I want to ignore in my nix build. Let's say the files I actually care about are also not in a single subfolder. Then I can't just move the flake.nix to that subfolder either.

[CuriousCosmic]

Oh yeah in that case it'd be a problem. There might be a way around that but that case definitely isn't ideal. albeit you could probably sparse-checkout your repo to avoid that if you don't need all of it.

definitely not ideal and I agree that until lazy file mapping, content addressed derivations, and file deduplication get implemented that the UX will be rough in some cases.