Tolerate uv truncated pyvenv.cfg version_info (#153)

## What

uv `0.11.22`
([astral-sh/uv#19890](astral-sh/uv#19890))
changed seeded venvs to record only `major.minor` in `pyvenv.cfg` (e.g.
`version_info = 3.14`) instead of the full `3.14.6`. pre-commit's
`health_check` does an exact-string comparison against our
`_version_info` override, so the second hook run failed with:

```
AssertionError: BUG: expected environment for python to be healthy immediately after install
virtualenv python version did not match created version:
- actual version: 3.14.6
- expected version: 3.14
```

## Fix

Override `python.health_check` with a prefix-aware comparison that
checks only the version components uv actually wrote, so it passes
whether uv records two or three components. The now-redundant
`_version_info` monkeypatch is dropped — `health_check` was its only
consumer.

Verified by reproducing the issue scenario end-to-end with uv `0.11.22`
(fails on `main`, passes here) and added unit tests covering
truncated/full/mismatched/missing-config cases.

Fixes #152

Author: gaborbernat

pyproject.toml

@@ -89,7 +89,6 @@ lint.select = [
   "ALL",
 ]
 lint.ignore = [
-  "ANN101", # no type annotation for self
   "ANN401", # allow Any as type annotation
   "COM812", # Conflict with formatter
   "CPY",    # No copyright statements

src/pre_commit_uv/__init__.py

@@ -4,11 +4,20 @@
 
 # only import built-ins at top level to avoid interpreter startup overhead
 import os
+import pathlib
 import sys
-from typing import TYPE_CHECKING
+from typing import TYPE_CHECKING, cast
 
 if TYPE_CHECKING:
-    from collections.abc import Sequence
+    from collections.abc import Callable, Sequence
+    from typing import Protocol
+
+    from pre_commit.prefix import Prefix
+
+    class _PatchablePython(Protocol):
+        install_environment: Callable[[Prefix, str, Sequence[str]], None]
+        health_check: Callable[[Prefix, str], str | None]
+
 
 _original_main = None
 
@@ -57,9 +66,6 @@ def _new_main(argv: Sequence[str] | None = None) -> int:
 
     from pre_commit.languages import python  # noqa: PLC0415
 
-    if TYPE_CHECKING:
-        from pre_commit.prefix import Prefix  # noqa: PLC0415
-
     def _install_environment(
         prefix: Prefix,
         version: str,
@@ -121,17 +127,48 @@ def uv_version() -> str:
 
         return _metadata_version("uv")
 
-    @cache
-    def _version_info(exe: str) -> str:
-        from pre_commit.util import CalledProcessError, cmd_output  # noqa: PLC0415
-
-        prog = 'import sys;print(".".join(str(p) for p in sys.version_info[0:3]))'
-        try:
-            return cmd_output(exe, "-S", "-c", prog)[1].strip()
-        except CalledProcessError:
-            return f"<<error retrieving version from {exe}>>"
-
-    python.install_environment = _install_environment  # ty: ignore[invalid-assignment]
-    python._version_info = _version_info  # noqa: SLF001
+    patched = cast("_PatchablePython", python)
+    patched.install_environment = _install_environment
+    patched.health_check = _health_check
     assert _original_main is not None  # noqa: S101
     return _original_main(argv)
+
+
+def _version_info(exe: str) -> str:
+    from pre_commit.util import CalledProcessError, cmd_output  # noqa: PLC0415
+
+    prog = 'import sys;print(".".join(str(p) for p in sys.version_info[0:3]))'
+    try:
+        return cmd_output(exe, "-S", "-c", prog)[1].strip()
+    except CalledProcessError:
+        return f"<<error retrieving version from {exe}>>"
+
+
+def _health_check(prefix: Prefix, version: str) -> str | None:
+    # uv may record fewer version components in pyvenv.cfg than pre-commit expects (e.g. "3.14" vs "3.14.6"),
+    # so compare only the components uv actually wrote rather than requiring an exact string match
+    from pre_commit.lang_base import environment_dir  # noqa: PLC0415
+    from pre_commit.languages import python  # noqa: PLC0415
+    from pre_commit.util import win_exe  # noqa: PLC0415
+
+    pyvenv_cfg = pathlib.Path(environment_dir(prefix, python.ENVIRONMENT_DIR, version)) / "pyvenv.cfg"
+    if not pyvenv_cfg.exists():
+        return "pyvenv.cfg does not exist (old virtualenv?)"
+
+    cfg = python._read_pyvenv_cfg(str(pyvenv_cfg))  # noqa: SLF001
+    if "version_info" not in cfg:
+        return "created virtualenv's pyvenv.cfg is missing `version_info`"
+    expected = cfg["version_info"].split(".")
+
+    py_exe = prefix.path(python.bin_dir(str(pyvenv_cfg.parent)), win_exe("python"))
+    targets = [("virtualenv python", py_exe)]
+    if "base-executable" in cfg:
+        targets.append(("base executable", cfg["base-executable"]))
+    for label, exe in targets:
+        if (actual := _version_info(exe)).split(".")[: len(expected)] != expected:
+            return (
+                f"{label} version did not match created version:\n"
+                f"- actual version: {actual}\n"
+                f"- expected version: {cfg['version_info']}\n"
+            )
+    return None

tests/test_health_check.py

@@ -0,0 +1,77 @@
+from __future__ import annotations
+
+import sys
+from typing import TYPE_CHECKING
+
+from pre_commit.languages import python
+from pre_commit.prefix import Prefix
+
+from pre_commit_uv import _health_check
+
+if TYPE_CHECKING:
+    from pathlib import Path
+
+version = "default"
+major_minor = f"{sys.version_info[0]}.{sys.version_info[1]}"
+full_version = ".".join(str(p) for p in sys.version_info[0:3])
+wrong_version = f"{sys.version_info[0]}.{sys.version_info[1] + 1}"
+
+
+def _make_env(tmp_path: Path, pyvenv_cfg: str | None) -> Prefix:
+    envdir = tmp_path / f"py_env-{version}"
+    bin_dir = python.bin_dir(str(envdir))
+    (tmp_path / bin_dir).mkdir(parents=True)
+    (tmp_path / bin_dir / python.win_exe("python")).symlink_to(sys.executable)
+    if pyvenv_cfg is not None:
+        (envdir / "pyvenv.cfg").write_text(pyvenv_cfg)
+    return Prefix(str(tmp_path))
+
+
+def test_health_check_truncated_version_passes(tmp_path: Path) -> None:
+    """uv >=0.11.22 writes only the major.minor into pyvenv.cfg (see issue #152)."""
+    prefix = _make_env(tmp_path, f"version_info = {major_minor}\nbase-executable = {sys.executable}\n")
+
+    assert _health_check(prefix, version) is None
+
+
+def test_health_check_full_version_passes(tmp_path: Path) -> None:
+    prefix = _make_env(tmp_path, f"version_info = {full_version}\nbase-executable = {sys.executable}\n")
+
+    assert _health_check(prefix, version) is None
+
+
+def test_health_check_no_base_executable_passes(tmp_path: Path) -> None:
+    prefix = _make_env(tmp_path, f"version_info = {major_minor}\n")
+
+    assert _health_check(prefix, version) is None
+
+
+def test_health_check_version_mismatch_fails(tmp_path: Path) -> None:
+    prefix = _make_env(tmp_path, f"version_info = {wrong_version}\n")
+
+    result = _health_check(prefix, version)
+
+    assert result is not None
+    assert "virtualenv python version did not match created version" in result
+    assert f"- expected version: {wrong_version}" in result
+
+
+def test_health_check_base_executable_mismatch_fails(tmp_path: Path) -> None:
+    prefix = _make_env(tmp_path, f"version_info = {major_minor}\nbase-executable = /does/not/exist/python\n")
+
+    result = _health_check(prefix, version)
+
+    assert result is not None
+    assert "base executable version did not match created version" in result
+
+
+def test_health_check_missing_pyvenv_cfg(tmp_path: Path) -> None:
+    prefix = _make_env(tmp_path, None)
+
+    assert _health_check(prefix, version) == "pyvenv.cfg does not exist (old virtualenv?)"
+
+
+def test_health_check_missing_version_info(tmp_path: Path) -> None:
+    prefix = _make_env(tmp_path, "home = /usr\n")
+
+    assert _health_check(prefix, version) == "created virtualenv's pyvenv.cfg is missing `version_info`"