diff --git a/Libraries/PyKotor/tests/cli/test_json_commands.py b/Libraries/PyKotor/tests/cli/test_json_commands.py
index 67a02752f..6e3f6ce6b 100644
--- a/Libraries/PyKotor/tests/cli/test_json_commands.py
+++ b/Libraries/PyKotor/tests/cli/test_json_commands.py
@@ -28,6 +28,7 @@
 from pykotor.resource.type import ResourceType
 from pykotor.tools.resource_json import (
     _serialize_mdl_face,
+    _supports_live_progress,
     export_installation_to_json_tree,
     iter_installation_resource_documents,
     serialize_file_resource_document,
@@ -922,3 +923,43 @@ def fake_main(argv: list[str]) -> int:
     assert "--merge-module" in captured_argv
     assert captured_argv.count("--merge-path") == 2
     assert "--merge-conflict-policy" in captured_argv
+
+
+class _FakeTtyStream:
+    def __init__(self, tty: bool) -> None:
+        self._tty = tty
+
+    def isatty(self) -> bool:
+        return self._tty
+
+
+@pytest.mark.parametrize(
+    ("env", "expected"),
+    [
+        ({"CI": "true"}, False),
+        ({"GITHUB_ACTIONS": "1"}, False),
+        ({}, True),
+    ],
+)
+def test_supports_live_progress_disables_in_ci(
+    env: dict[str, str],
+    expected: bool,
+    monkeypatch: pytest.MonkeyPatch,
+) -> None:
+    monkeypatch.delenv("CI", raising=False)
+    monkeypatch.delenv("GITHUB_ACTIONS", raising=False)
+    for key, value in env.items():
+        monkeypatch.setenv(key, value)
+
+    stream = _FakeTtyStream(tty=True)
+    assert _supports_live_progress(stream) is expected
+
+
+def test_supports_live_progress_requires_tty_when_not_in_ci(
+    monkeypatch: pytest.MonkeyPatch,
+) -> None:
+    monkeypatch.delenv("CI", raising=False)
+    monkeypatch.delenv("GITHUB_ACTIONS", raising=False)
+
+    assert _supports_live_progress(_FakeTtyStream(tty=False)) is False
+    assert _supports_live_progress(_FakeTtyStream(tty=True)) is True
diff --git a/Libraries/PyKotor/tests/diff_tool/test_cli_utils.py b/Libraries/PyKotor/tests/diff_tool/test_cli_utils.py
new file mode 100644
index 000000000..3b523acd3
--- /dev/null
+++ b/Libraries/PyKotor/tests/diff_tool/test_cli_utils.py
@@ -0,0 +1,99 @@
+"""Regression tests for diff_tool CLI path normalization and install detection."""
+
+from __future__ import annotations
+
+import pathlib
+import sys
+import tempfile
+import unittest
+
+THIS_SCRIPT_PATH = pathlib.Path(__file__).resolve()
+PYKOTOR_PATH = THIS_SCRIPT_PATH.parents[2].joinpath("src")
+UTILITY_PATH = THIS_SCRIPT_PATH.parents[4].joinpath("Libraries", "Utility", "src")
+
+
+def add_sys_path(p: pathlib.Path) -> None:
+    working_dir = str(p)
+    if working_dir not in sys.path:
+        sys.path.append(working_dir)
+
+
+if PYKOTOR_PATH.joinpath("pykotor").exists():
+    add_sys_path(PYKOTOR_PATH)
+if UTILITY_PATH.joinpath("utility").exists():
+    add_sys_path(UTILITY_PATH)
+
+from pykotor.diff_tool.cli_utils import (  # noqa: E402
+    is_kotor_install_dir,
+    normalize_path_arg,
+)
+
+
+class TestNormalizePathArg(unittest.TestCase):
+    def test_none_and_empty(self) -> None:
+        self.assertIsNone(normalize_path_arg(None))
+        self.assertIsNone(normalize_path_arg(""))
+        self.assertIsNone(normalize_path_arg("   "))
+
+    def test_strips_surrounding_quotes(self) -> None:
+        self.assertEqual(
+            normalize_path_arg('"C:\\Program Files\\KOTOR"'),
+            "C:\\Program Files\\KOTOR",
+        )
+        self.assertEqual(
+            normalize_path_arg("'C:/Games/KOTOR'"),
+            "C:/Games/KOTOR",
+        )
+
+    def test_strips_trailing_slashes_after_quote_removal(self) -> None:
+        self.assertEqual(
+            normalize_path_arg('"C:\\Program Files\\KOTOR\\"'),
+            "C:\\Program Files\\KOTOR",
+        )
+
+    def test_mangled_powershell_quote_space_path(self) -> None:
+        mangled = 'C:\\Steam\\steamapps\\common\\swkotor" C:\\Other\\path'
+        self.assertEqual(
+            normalize_path_arg(mangled),
+            "C:\\Steam\\steamapps\\common\\swkotor",
+        )
+
+    def test_removes_embedded_quotes(self) -> None:
+        self.assertEqual(
+            normalize_path_arg('C:\\"broken"\\path'),
+            "C:\\broken\\path",
+        )
+
+
+class TestIsKotorInstallDir(unittest.TestCase):
+    def test_valid_installation(self) -> None:
+        with tempfile.TemporaryDirectory() as tmp:
+            root = pathlib.Path(tmp)
+            (root / "chitin.key").write_bytes(b"key")
+            self.assertTrue(is_kotor_install_dir(root))
+
+    def test_missing_chitin_key(self) -> None:
+        with tempfile.TemporaryDirectory() as tmp:
+            root = pathlib.Path(tmp)
+            self.assertFalse(is_kotor_install_dir(root))
+
+    def test_file_path_is_not_install(self) -> None:
+        with tempfile.NamedTemporaryFile() as tmp_file:
+            self.assertFalse(is_kotor_install_dir(pathlib.Path(tmp_file.name)))
+
+    @unittest.skipIf(
+        sys.platform == "win32",
+        "Case-mismatch path semantics differ on Windows filesystems.",
+    )
+    def test_case_mismatched_chitin_key_path(self) -> None:
+        with tempfile.TemporaryDirectory() as tmp:
+            root = pathlib.Path(tmp) / "KotorInstall"
+            root.mkdir()
+            (root / "chitin.key").write_bytes(b"key")
+
+            mismatched = pathlib.Path(tmp) / "kotorinstall"
+            self.assertTrue(is_kotor_install_dir(mismatched))
+
+
+if __name__ == "__main__":
+    unittest.main()