Harden computer-action helper usage guard assertions

Co-authored-by: Shri Sukhani <shrisukhani@users.noreply.github.com>

Author: cursoragent

tests/test_computer_action_endpoint_helper_usage.py

@@ -16,3 +16,5 @@ def test_computer_action_managers_use_shared_endpoint_normalizer():
         module_text = Path(module_path).read_text(encoding="utf-8")
         assert "normalize_computer_action_endpoint(" in module_text
         assert "session.computer_action_endpoint" not in module_text
+        assert "computer_action_endpoint must be a string" not in module_text
+        assert "computer_action_endpoint must not contain control characters" not in module_text