fix(client,langchain,tests): closed-loop guard, relationships TODO, remove dead fixture

- client.py: raise RuntimeError in _run() when event loop is closed (prevents
  obscure 'Event loop is closed' error when client reused after close())
- langchain graph.py: add TODO comment on empty relationships list explaining
  schema text lacks direction info; document Cypher introspection path
- test_sdk.py: remove unused run fixture (manual event loop, never referenced
  by any test); remove orphaned asyncio import

Author: polaz

coordinode/client.py

@@ -365,6 +365,8 @@ def close(self) -> None:
             self._loop.close()
 
     def _run(self, coro: Any) -> Any:
+        if self._loop.is_closed():
+            raise RuntimeError("CoordinodeClient has been closed and cannot be reused")
         if not self._connected:
             self._loop.run_until_complete(self._async.connect())
             self._connected = True

langchain-coordinode/langchain_coordinode/graph.py

@@ -129,6 +129,9 @@ def _parse_schema(schema_text: str) -> dict[str, Any]:
     """
     node_props: dict[str, list[dict[str, str]]] = {}
     rel_props: dict[str, list[dict[str, str]]] = {}
+    # TODO: CoordiNode's schema text does not include relationship direction info
+    # (start_label → end_label). Populate via Cypher introspection when needed:
+    # MATCH (a)-[r]->(b) RETURN DISTINCT labels(a)[0], type(r), labels(b)[0]
     relationships: list[dict[str, str]] = []
 
     in_nodes = False

tests/integration/test_sdk.py

@@ -7,7 +7,6 @@
 
 from __future__ import annotations
 
-import asyncio
 import os
 import uuid
 
@@ -27,13 +26,6 @@ def client():
         yield c
 
 
-@pytest.fixture(scope="module")
-def run():
-    """Run a coroutine synchronously (re-used event loop for the module)."""
-    loop = asyncio.new_event_loop()
-    yield loop.run_until_complete
-    loop.close()
-
 
 def uid() -> str:
     return uuid.uuid4().hex[:8]