🐛 fix(venv): seed pip into hook environments (#114)

uv venv does not install pip by default, unlike python -m venv. Hooks
like mypy that internally call `python -m pip install` to fetch type
stubs fail with "No module named pip" in the created environment.

Passing --seed to uv venv restores pip/setuptools availability,
matching standard venv behavior and fixing hooks that depend on pip
at runtime.

Fixes #61

Author: gaborbernat

src/pre_commit_uv/__init__.py

@@ -74,6 +74,7 @@ def _install_environment(
             "--project",
             project_root_dir,
             "venv",
+            "--seed",
             environment_dir(prefix, python.ENVIRONMENT_DIR, version),
             "-p",
             py,

tests/test_main.py

@@ -68,6 +68,21 @@ def test_install(git_repo: Path, caplog: pytest.LogCaptureFixture, monkeypatch:
     ]
 
 
+def test_install_seeds_pip(git_repo: Path, monkeypatch: pytest.MonkeyPatch) -> None:
+    monkeypatch.setenv("FORCE_PRE_COMMIT_UV_PATCH", "1")
+
+    import pre_commit_uv  # noqa: PLC0415
+
+    pre_commit_uv._patch()  # noqa: SLF001
+    main.main(["install-hooks", "-c", str(git_repo / precommit_file)])
+
+    env_dirs = list((git_repo / "store").rglob("py_env-*"))
+    assert env_dirs, "expected at least one hook environment"
+    py = next((env_dirs[0] / "bin").glob("python*"))
+    result = check_output([str(py), "-c", "import pip"], encoding="utf-8")
+    assert not result
+
+
 test_install_with_uv_config_cases: list[tuple[str, str]] = [
     (
         "pyproject.toml",