Add extension key-display helper usage guard

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

Author: cursoragent

CONTRIBUTING.md

@@ -131,6 +131,7 @@ This runs lint, format checks, compile checks, tests, and package build.
   - `tests/test_examples_syntax.py` (example script syntax guardrail),
   - `tests/test_extension_create_helper_usage.py` (extension create-input normalization helper usage enforcement),
   - `tests/test_extension_create_metadata_usage.py` (extension create-helper shared operation-metadata prefix usage enforcement),
+  - `tests/test_extension_key_display_helper_usage.py` (extension missing-key display helper usage enforcement),
   - `tests/test_extension_operation_metadata_import_boundary.py` (extension operation-metadata import boundary enforcement),
   - `tests/test_extension_operation_metadata_usage.py` (extension manager operation-metadata usage enforcement),
   - `tests/test_extension_parse_usage_boundary.py` (centralized extension list parse-helper usage boundary enforcement),

tests/test_architecture_marker_usage.py

@@ -107,6 +107,7 @@
     "tests/test_extension_operation_metadata_import_boundary.py",
     "tests/test_extension_operation_metadata_usage.py",
     "tests/test_extension_parse_usage_boundary.py",
+    "tests/test_extension_key_display_helper_usage.py",
     "tests/test_extension_request_function_parse_boundary.py",
     "tests/test_extension_request_helper_usage.py",
     "tests/test_extension_request_internal_reuse.py",

tests/test_extension_key_display_helper_usage.py

@@ -0,0 +1,15 @@
+from pathlib import Path
+
+import pytest
+
+pytestmark = pytest.mark.architecture
+
+EXTENSION_UTILS_MODULE = Path("hyperbrowser/client/managers/extension_utils.py")
+
+
+def test_extension_utils_uses_format_string_key_for_error():
+    module_text = EXTENSION_UTILS_MODULE.read_text(encoding="utf-8")
+
+    assert "format_string_key_for_error(" in module_text
+    assert "_MAX_DISPLAYED_MISSING_KEY_LENGTH" in module_text
+    assert "_safe_stringify_key(" in module_text