Add architecture guard for sync/async example parity

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

Author: cursoragent

CONTRIBUTING.md

@@ -94,7 +94,8 @@ This runs lint, format checks, compile checks, tests, and package build.
   - `tests/test_core_type_helper_usage.py` (core transport/config/header/file/polling/session/error/parsing manager+tool module enforcement of shared plain-type helper usage),
   - `tests/test_contributing_architecture_guard_listing.py` (`CONTRIBUTING.md` architecture-guard inventory completeness enforcement),
   - `tests/test_examples_syntax.py` (example script syntax guardrail),
-  - `tests/test_docs_python3_commands.py` (`README`/`CONTRIBUTING`/examples python3 command consistency enforcement).
+  - `tests/test_docs_python3_commands.py` (`README`/`CONTRIBUTING`/examples python3 command consistency enforcement),
+  - `tests/test_example_sync_async_parity.py` (sync/async example parity enforcement).
 
 ## Code quality conventions
 

tests/test_architecture_marker_usage.py

@@ -24,6 +24,7 @@
     "tests/test_contributing_architecture_guard_listing.py",
     "tests/test_examples_syntax.py",
     "tests/test_docs_python3_commands.py",
+    "tests/test_example_sync_async_parity.py",
 )
 
 

tests/test_example_sync_async_parity.py

@@ -0,0 +1,23 @@
+from pathlib import Path
+
+import pytest
+
+pytestmark = pytest.mark.architecture
+
+
+def test_examples_have_sync_async_parity_by_prefix():
+    example_names = {path.stem for path in Path("examples").glob("*.py")}
+
+    sync_examples = {name for name in example_names if name.startswith("sync_")}
+    async_examples = {name for name in example_names if name.startswith("async_")}
+
+    assert sync_examples != []
+    assert async_examples != []
+
+    for sync_name in sync_examples:
+        expected_async = sync_name.replace("sync_", "async_", 1)
+        assert expected_async in example_names
+
+    for async_name in async_examples:
+        expected_sync = async_name.replace("async_", "sync_", 1)
+        assert expected_sync in example_names