Add AST import-helper import boundary architecture guard

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

Author: cursoragent

CONTRIBUTING.md

@@ -91,6 +91,7 @@ This runs lint, format checks, compile checks, tests, and package build.
   - `tests/test_ast_function_source_helper_usage.py` (shared AST function-source helper usage enforcement across architecture guard suites),
   - `tests/test_ast_function_source_import_boundary.py` (shared AST function-source helper import boundary enforcement across test modules),
   - `tests/test_ast_function_source_utils.py` (shared AST function-source helper contract validation),
+  - `tests/test_ast_import_helper_import_boundary.py` (shared AST import-helper import boundary enforcement across test modules),
   - `tests/test_ast_import_helper_usage.py` (shared AST import-helper usage enforcement across AST import-boundary guard suites),
   - `tests/test_binary_file_open_helper_usage.py` (shared binary file open helper usage enforcement),
   - `tests/test_browser_use_payload_helper_usage.py` (browser-use payload helper usage enforcement),

tests/test_architecture_marker_usage.py

@@ -20,6 +20,7 @@
     "tests/test_ast_function_source_helper_usage.py",
     "tests/test_ast_function_source_import_boundary.py",
     "tests/test_ast_function_source_utils.py",
+    "tests/test_ast_import_helper_import_boundary.py",
     "tests/test_ast_import_helper_usage.py",
     "tests/test_guardrail_ast_utils.py",
     "tests/test_helper_transport_usage_boundary.py",

tests/test_ast_import_helper_import_boundary.py

@@ -0,0 +1,35 @@
+import ast
+from pathlib import Path
+
+import pytest
+
+pytestmark = pytest.mark.architecture
+
+
+EXPECTED_AST_IMPORT_HELPER_IMPORTERS = (
+    "tests/test_ast_function_source_helper_usage.py",
+    "tests/test_ast_function_source_import_boundary.py",
+)
+
+
+def _imports_ast_import_helper(module_text: str) -> bool:
+    module_ast = ast.parse(module_text)
+    for node in module_ast.body:
+        if not isinstance(node, ast.ImportFrom):
+            continue
+        if node.module != "tests.ast_import_utils":
+            continue
+        if any(alias.name == "imports_collect_function_sources" for alias in node.names):
+            return True
+    return False
+
+
+def test_ast_import_helper_imports_are_centralized():
+    discovered_modules: list[str] = []
+    for module_path in sorted(Path("tests").glob("test_*.py")):
+        module_text = module_path.read_text(encoding="utf-8")
+        if not _imports_ast_import_helper(module_text):
+            continue
+        discovered_modules.append(module_path.as_posix())
+
+    assert discovered_modules == list(EXPECTED_AST_IMPORT_HELPER_IMPORTERS)