Keep maintainer help portable on Windows

tests/test_script_help.py

@@ -4,6 +4,7 @@ from __future__ import annotations
 
 import subprocess
 import sys
+from os import environ
 from pathlib import Path
 
 import pytest
@@ -31,3 +32,19 @@ def test_script_help_exits_cleanly(script: str) -> None:
 
     assert result.returncode == 0, result.stderr
     assert "usage:" in result.stdout
+
+
+def test_visible_groundtruth_help_is_cp1252_safe() -> None:
+    env = environ.copy()
+    env["PYTHONIOENCODING"] = "cp1252"
+    result = subprocess.run(  # noqa: S603 -- fixed interpreter and repository-owned script path
+        [sys.executable, str(ROOT / "scripts" / "visible_groundtruth.py"), "--help"],
+        cwd=ROOT,
+        env=env,
+        capture_output=True,
+        text=True,
+        check=False,
+    )
+
+    assert result.returncode == 0, result.stderr
+    assert "usage:" in result.stdout