Add PEP-735 dependency groups

This introduces a breaking change.

Previously `dev-dependencies` were remapped as optional dependencies, still named `dev-dependencies`:
``` nix
virtualenv = editablePythonSet.mkVirtualEnv "hello-world-dev-env" {
  hello-world = [ "dev-dependencies" ];
};
```

Will now be written simply as `dev`, refering to a dependency group, and not an optional feature:
``` nix
virtualenv = editablePythonSet.mkVirtualEnv "hello-world-dev-env" {
  hello-world = [ "dev" ];
};
```

This mirrors new Uv behaviour introduced in astral-sh/uv#8272.
See pyproject-nix/pyproject.nix#170 for pyproject.nix changes.

Author: adisbladis

dev/checks.nix

@@ -68,7 +68,8 @@ let
       ws = uv2nix.workspace.loadWorkspace { workspaceRoot = root; };
 
       # Build Python environment based on builder implementation
-      pythonEnv = let
+      pythonEnv = (
+        let
           # Generate overlay
           overlay = ws.mkPyprojectOverlay { inherit sourcePreference environ; };
 
@@ -81,7 +82,8 @@ let
 
         in
         # Render venv
-        pythonSet.pythonPkgsHostHost.mkVirtualEnv "test-venv" spec;
+        pythonSet.pythonPkgsHostHost.mkVirtualEnv "test-venv" spec
+      );
 
     in
     if check != null then

flake.lock

@@ -10,7 +10,7 @@
     nix-github-actions.url = "github:nix-community/nix-github-actions";
     nix-github-actions.inputs.nixpkgs.follows = "nixpkgs";
 
-    pyproject-nix.url = "github:nix-community/pyproject.nix";
+    pyproject-nix.url = "github:nix-community/pyproject.nix/pep735";
     pyproject-nix.inputs.nixpkgs.follows = "nixpkgs";
     pyproject-nix.inputs.nix-github-actions.follows = "nix-github-actions";
     pyproject-nix.inputs.mdbook-nixdoc.follows = "mdbook-nixdoc";

flake.nix

@@ -100,6 +100,7 @@ in
             passthru = {
               dependencies = mkSpec package.dependencies;
               optional-dependencies = mapAttrs (_: mkSpec) package.optional-dependencies;
+              dependency-groups = mapAttrs (_: mkSpec) package.dev-dependencies;
               inherit format;
             };
 

lib/build.nix

@@ -0,0 +1,27 @@
+[project]
+name = "dependency-groups"
+version = "0.1.0"
+description = "Testing dependency groups"
+readme = "README.md"
+requires-python = ">=3.12"
+dependencies = []
+
+# Dependency groups are rendered in uv.lock as package.dev-dependencies
+[dependency-groups]
+group-a = ["urllib3"]
+
+# Special older syntax for dependency groups
+# tool.uv.dev-dependencies are rendered in lock file as:
+#
+# [package.dev-dependencies]
+# dev = [
+#     { name = "arpeggio" },
+# ]
+[tool.uv]
+dev-dependencies = [
+    "arpeggio"
+]
+
+[build-system]
+requires = ["hatchling"]
+build-backend = "hatchling.build"

lib/fixtures/dependency-groups/pyproject.toml

@@ -114,8 +114,8 @@
 
             # Build virtual environment
             virtualenv = editablePythonSet.mkVirtualEnv "hello-world-dev-env" {
-              # Add hello world with it's dev dependencies
-              hello-world = [ "dev-dependencies" ];
+              # Add hello world with it's dev dependency group
+              hello-world = [ "dev" ];
             };
 
           in