fix: editable subpackage (#895)

Proposed fix for
#893.

- **fix: nox + uv downstream improvements**
- **fix: editable subpackage issue**

---------

Signed-off-by: Henry Schreiner <[email protected]>

Author: henryiii

noxfile.py

@@ -230,13 +230,7 @@ def downstream(session: nox.Session) -> None:
 
     # If running in manylinux:
     #   docker run --rm -v $PWD:/sk -w /sk -t quay.io/pypa/manylinux2014_x86_64:latest \
-    #       pipx run --system-site-packages nox -s downstream -- https://github.com/...
-    # (requires tomli, so allowing access to system-site-packages)
-
-    if sys.version_info < (3, 11):
-        import tomli as tomllib
-    else:
-        import tomllib
+    #       pipx run nox -s downstream -- https://github.com/...
 
     parser = argparse.ArgumentParser(prog=f"{Path(sys.argv[0]).name} -s downstream")
     parser.add_argument("project", help="A project to build")
@@ -270,9 +264,7 @@ def downstream(session: nox.Session) -> None:
         session.chdir(proj_dir)
 
     # Read and strip requirements
-    pyproject_toml = Path("pyproject.toml")
-    with pyproject_toml.open("rb") as f:
-        pyproject = tomllib.load(f)
+    pyproject = nox.project.load_toml("pyproject.toml")
     requires = [
         x
         for x in pyproject["build-system"]["requires"]
@@ -289,7 +281,7 @@ def downstream(session: nox.Session) -> None:
         session.chdir(args.subdir)
 
     if args.editable:
-        session.install("-e.")
+        session.install("-e.", "--no-build-isolation")
     else:
         session.run(
             "python",

pyproject.toml

@@ -126,6 +126,10 @@ version.source = "vcs"
 build.hooks.vcs.version-file = "src/scikit_build_core/_version.py"
 
 
+[tool.uv.pip]
+reinstall-package = ["scikit-build-core"]
+
+
 [tool.pytest.ini_options]
 minversion = "7.0"
 addopts = ["-rfEsX", "--strict-markers", "--strict-config"]

src/scikit_build_core/resources/_editable_redirect.py

@@ -87,21 +87,26 @@ def find_spec(
             submodule_search_locations = list(self.submodule_search_locations[fullname])
         else:
             submodule_search_locations = None
+
         if fullname in self.known_wheel_files:
             redir = self.known_wheel_files[fullname]
             if self.rebuild_flag:
                 self.rebuild()
             return importlib.util.spec_from_file_location(
                 fullname,
                 os.path.join(self.dir, redir),
-                submodule_search_locations=submodule_search_locations,
+                submodule_search_locations=submodule_search_locations
+                if redir.endswith(("__init__.py", "__init__.pyc"))
+                else None,
             )
         if fullname in self.known_source_files:
             redir = self.known_source_files[fullname]
             return importlib.util.spec_from_file_location(
                 fullname,
                 redir,
-                submodule_search_locations=submodule_search_locations,
+                submodule_search_locations=submodule_search_locations
+                if redir.endswith(("__init__.py", "__init__.pyc"))
+                else None,
             )
         return None