🐛 fix(discovery): don't probe PATH directories as interpreters

docs/changelog/+skip-path-dir-probe.bugfix.rst

@@ -0,0 +1,3 @@
+:func:`~python_discovery.iter_interpreters` with no key no longer probes each ``PATH`` directory as if it were an
+interpreter. The empty spec made the literal name check point at the directory itself, so every entry cost a failed
+subprocess and a retry.

src/python_discovery/_discovery.py

@@ -496,8 +496,9 @@ def path_exe_finder(
         direct = f"{direct}.exe"
 
     def path_exes(path: Path) -> Generator[tuple[Path, bool], None, None]:
+        # an empty spec (enumerating everything) would make the direct path the PATH directory itself
         direct_path = path / direct
-        if direct_path.exists():
+        if direct_path.is_file():
             yield direct_path, impl_must_match
 
         for exe in path.iterdir():

tests/test_iter_interpreters.py

@@ -144,6 +144,21 @@ def test_iter_interpreters_no_key_probes_variant_builds_on_path(
     assert str(exe) in [call.args[0] for call in from_exe.call_args_list]
 
 
+@pytest.mark.usefixtures("uv_dir")
+def test_iter_interpreters_no_key_does_not_probe_path_directories(
+    tmp_path: Path, monkeypatch: pytest.MonkeyPatch, mocker: MockerFixture
+) -> None:
+    exe = tmp_path / "bin" / f"python3.99{'.exe' if IS_WIN else ''}"
+    exe.parent.mkdir()
+    exe.touch()
+    monkeypatch.setenv("PATH", str(exe.parent))
+    from_exe = mocker.patch("python_discovery._discovery.PathPythonInfo.from_exe", return_value=None)
+
+    list(iter_interpreters())
+
+    assert [call.args[0] for call in from_exe.call_args_list] == [str(exe)]
+
+
 @pytest.mark.usefixtures("uv_dir")
 def test_iter_interpreters_dedups_symlinks(
     tmp_path: Path,