fix(storage): pin Redis client to RESP2 so FT.SEARCH decodes correctly

knowledge-graph-api/storage/redis_vector.py

@@ -17,9 +17,17 @@ class RedisVectorStore:
     """Async Redis vector store backed by RedisSearch."""
 
     def __init__(self) -> None:
+        # Force RESP2 protocol. Redis Stack 7.2+ negotiates RESP3 by
+        # default, which makes the server reply to FT.SEARCH with a
+        # dict (``{b'total_results': N, b'results': [...]}``). The
+        # redis-py ``ft().search()`` helper still parses RESP2 list
+        # shape, so on RESP3 it silently returns ``total=0, docs=[]``
+        # for queries that DO match. Pinning protocol=2 makes the
+        # response a positional list and search results decode correctly.
         self._client = aioredis.from_url(
             settings.REDIS_URL,
             decode_responses=False,
+            protocol=2,
         )
         self._index_name = settings.REDIS_INDEX_NAME