fix(terminal): guard invalid command values

tests/tools/test_terminal_none_command_guard.py

@@ -0,0 +1,21 @@
+"""Regression tests for invalid/None terminal command handling."""
+
+import json
+
+from tools.terminal_tool import _transform_sudo_command, terminal_tool
+
+
+def test_transform_sudo_command_none_returns_cleanly():
+    transformed, sudo_stdin = _transform_sudo_command(None)
+
+    assert transformed is None
+    assert sudo_stdin is None
+
+
+def test_terminal_tool_none_command_returns_clean_error():
+    result = json.loads(terminal_tool(None))  # type: ignore[arg-type]
+
+    assert result["exit_code"] == -1
+    assert result["status"] == "error"
+    assert "expected string" in result["error"].lower()
+    assert "nonetype" in result["error"].lower()