diff --git a/Libraries/PyKotor/tests/common/test_diff_cli_utils.py b/Libraries/PyKotor/tests/common/test_diff_cli_utils.py
new file mode 100644
index 000000000..99fbdd938
--- /dev/null
+++ b/Libraries/PyKotor/tests/common/test_diff_cli_utils.py
@@ -0,0 +1,31 @@
+"""Regression tests for diff_tool.cli_utils path normalization."""
+
+from __future__ import annotations
+
+import pytest
+
+from pykotor.diff_tool.cli_utils import normalize_path_arg
+
+
+@pytest.mark.parametrize(
+    ("raw", "expected"),
+    [
+        (None, None),
+        ("", None),
+        ("   ", None),
+        ("/tmp/kotor", "/tmp/kotor"),
+        ('"/tmp/kotor"', "/tmp/kotor"),
+        ("'/tmp/kotor'", "/tmp/kotor"),
+        (r'C:\Games\KOTOR\ ', r"C:\Games\KOTOR"),
+        (r'C:\Games\KOTOR\" C:\Other', r"C:\Games\KOTOR"),
+    ],
+)
+def test_normalize_path_arg_strips_quotes_and_whitespace(
+    raw: str | None,
+    expected: str | None,
+) -> None:
+    assert normalize_path_arg(raw) == expected
+
+
+def test_normalize_path_arg_removes_embedded_quotes() -> None:
+    assert normalize_path_arg('C:\\"Games\\"KOTOR') == r"C:\Games\KOTOR"
diff --git a/Libraries/PyKotor/tests/common/test_is_kotor_install_dir.py b/Libraries/PyKotor/tests/common/test_is_kotor_install_dir.py
new file mode 100644
index 000000000..cfd484135
--- /dev/null
+++ b/Libraries/PyKotor/tests/common/test_is_kotor_install_dir.py
@@ -0,0 +1,85 @@
+"""Regression tests for KOTOR install directory detection via CaseAwarePath."""
+
+from __future__ import annotations
+
+import sys
+from collections.abc import Callable
+from pathlib import Path
+
+import pytest
+
+from pykotor.diff_tool import cli_utils
+from pykotor.tools import patching
+from pykotor.tslpatcher.diff import engine
+
+InstallDirChecker = Callable[[Path], bool | None]
+
+_CHECKERS: tuple[tuple[str, InstallDirChecker], ...] = (
+    ("cli_utils", cli_utils.is_kotor_install_dir),
+    ("patching", patching.is_kotor_install_dir),
+    ("diff_engine", engine.is_kotor_install_dir),
+)
+
+
+@pytest.mark.parametrize("checker", [c for _, c in _CHECKERS], ids=[n for n, _ in _CHECKERS])
+def test_is_kotor_install_dir_true_when_chitin_key_present(
+    checker: InstallDirChecker,
+    tmp_path: Path,
+) -> None:
+    (tmp_path / "chitin.key").write_bytes(b"")
+    assert checker(tmp_path) is True
+
+
+@pytest.mark.parametrize("checker", [c for _, c in _CHECKERS], ids=[n for n, _ in _CHECKERS])
+def test_is_kotor_install_dir_false_without_chitin_key(
+    checker: InstallDirChecker,
+    tmp_path: Path,
+) -> None:
+    assert checker(tmp_path) is False
+
+
+@pytest.mark.parametrize("checker", [c for _, c in _CHECKERS], ids=[n for n, _ in _CHECKERS])
+def test_is_kotor_install_dir_false_for_missing_path(
+    checker: InstallDirChecker,
+    tmp_path: Path,
+) -> None:
+    assert checker(tmp_path / "does-not-exist") is False
+
+
+@pytest.mark.parametrize("checker", [c for _, c in _CHECKERS], ids=[n for n, _ in _CHECKERS])
+def test_is_kotor_install_dir_false_for_file_path(
+    checker: InstallDirChecker,
+    tmp_path: Path,
+) -> None:
+    file_path = tmp_path / "not-a-dir"
+    file_path.write_bytes(b"")
+    assert checker(file_path) is False
+
+
+@pytest.mark.parametrize("checker", [c for _, c in _CHECKERS], ids=[n for n, _ in _CHECKERS])
+@pytest.mark.skipif(
+    sys.platform == "win32",
+    reason="Case-mismatch path semantics differ on Windows filesystems.",
+)
+def test_is_kotor_install_dir_case_mismatched_install_path(
+    checker: InstallDirChecker,
+    tmp_path: Path,
+) -> None:
+    install_dir = tmp_path / "KotorInstall"
+    install_dir.mkdir()
+    (install_dir / "chitin.key").write_bytes(b"")
+
+    assert checker(tmp_path / "kotorinstall") is True
+
+
+@pytest.mark.parametrize("checker", [c for _, c in _CHECKERS], ids=[n for n, _ in _CHECKERS])
+@pytest.mark.skipif(
+    sys.platform == "win32",
+    reason="Case-mismatch path semantics differ on Windows filesystems.",
+)
+def test_is_kotor_install_dir_case_mismatched_chitin_key_name(
+    checker: InstallDirChecker,
+    tmp_path: Path,
+) -> None:
+    (tmp_path / "CHITIN.KEY").write_bytes(b"")
+    assert checker(tmp_path) is True