Add default open-prefix literal boundary guard

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

Author: cursoragent

CONTRIBUTING.md

@@ -138,6 +138,7 @@ This runs lint, format checks, compile checks, tests, and package build.
   - `tests/test_file_message_default_constant_import_boundary.py` (extension/session file-message default constant import boundary enforcement),
   - `tests/test_file_message_default_constant_usage.py` (extension/session file-message default-prefix constant usage enforcement),
   - `tests/test_file_message_prefix_literal_boundary.py` (extension/session file-message prefix literal centralization in shared metadata modules),
+  - `tests/test_file_open_default_prefix_literal_boundary.py` (shared default open-file prefix literal centralization in `hyperbrowser/client/file_utils.py`),
   - `tests/test_file_open_error_helper_import_boundary.py` (shared file-open error-message helper import boundary enforcement),
   - `tests/test_file_open_error_helper_usage.py` (shared file-open error-message helper usage enforcement),
   - `tests/test_file_path_display_helper_import_boundary.py` (shared file-path display helper import boundary enforcement),

tests/test_architecture_marker_usage.py

@@ -50,6 +50,7 @@
     "tests/test_model_request_wrapper_internal_reuse.py",
     "tests/test_tool_mapping_reader_usage.py",
     "tests/test_display_helper_usage.py",
+    "tests/test_file_open_default_prefix_literal_boundary.py",
     "tests/test_file_message_default_constant_import_boundary.py",
     "tests/test_file_message_default_constant_usage.py",
     "tests/test_file_message_prefix_literal_boundary.py",

tests/test_file_open_default_prefix_literal_boundary.py

@@ -0,0 +1,25 @@
+from pathlib import Path
+
+import pytest
+
+pytestmark = pytest.mark.architecture
+
+
+HYPERBROWSER_ROOT = Path(__file__).resolve().parents[1] / "hyperbrowser"
+ALLOWED_LITERAL_MODULE = Path("client/file_utils.py")
+DEFAULT_OPEN_PREFIX_LITERAL = "Failed to open file at path"
+
+
+def test_default_open_prefix_literal_is_centralized_in_file_utils():
+    violations: list[str] = []
+
+    for module_path in sorted(HYPERBROWSER_ROOT.rglob("*.py")):
+        relative_path = module_path.relative_to(HYPERBROWSER_ROOT)
+        if relative_path == ALLOWED_LITERAL_MODULE:
+            continue
+        module_text = module_path.read_text(encoding="utf-8")
+        if DEFAULT_OPEN_PREFIX_LITERAL not in module_text:
+            continue
+        violations.append(relative_path.as_posix())
+
+    assert violations == []