feat(vector): server-side kinds filter for search_similar (legacy fallback) + graceful solved-search degrade

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

harness/tht/vectorstore/rest_client.py

@@ -58,18 +58,28 @@ class VectorRestClient:
         return resp.json()
 
     def search_similar(
-        self, table_name: str, query_embedding: list[float], limit_count: int
+        self, table_name: str, query_embedding: list[float], limit_count: int,
+        kinds: list[str] | None = None,
     ) -> list[dict]:
         """Ricerca per similarità coseno su `vectors.<table_name>`: ritorna le righe
-        `{id, similarity, metadata}` ordinate per similarity decrescente."""
-        return self._call(
-            "search_similar",
-            {
-                "query_embedding": query_embedding,
-                "limit_count": limit_count,
-                "table_name": table_name,
-            },
-        ) or []
+        `{id, similarity, metadata}` ordinate per similarity decrescente. Con `kinds`
+        il filtro avviene server-side nel WHERE della RPC (evita la diluizione del
+        top-k quando piu' kind condividono la tabella, es. memory/solved_question).
+        Su un server legacy senza il parametro (PostgREST 404) ritenta senza filtro:
+        resta il post-filter client-side di RestSearcher."""
+        args = {
+            "query_embedding": query_embedding,
+            "limit_count": limit_count,
+            "table_name": table_name,
+        }
+        if kinds is not None:
+            try:
+                return self._call("search_similar", {**args, "kinds": kinds}) or []
+            except VectorRestError as e:
+                if "HTTP 404" not in str(e):
+                    raise
+                # funzione a 3 argomenti (pre-migrazione kinds): fallback senza filtro
+        return self._call("search_similar", args) or []
 
     def list_tables(self) -> list[dict]:
         """Tabelle vettoriali disponibili: `{table_name, vector_dimensions, …}`."""