fix(evidence): enforce active vector generations

harness/tests/test_search_similar_kinds.py

@@ -90,6 +90,25 @@ def test_search_similar_reraises_non_404_with_kinds(monkeypatch):
         _client().search_similar("memory", [0.1] * 4, 5, kinds=["memory"])
 
 
+def test_generation_filter_is_sent_exactly_and_legacy_404_fails_closed(monkeypatch):
+    calls = []
+
+    def fake_call(self, function, payload):
+        calls.append(payload)
+        raise VectorRestError("HTTP 404 missing filtered RPC")
+
+    monkeypatch.setattr(VectorRestClient, "_call", fake_call)
+    metadata_filter = {"vector_generation": "gen:abc", "document_ids": ["doc:1"]}
+    with pytest.raises(VectorRestError, match="404"):
+        _client().search_similar(
+            "evidence", [0.1] * 4, 5, kinds=["evidence"], metadata_filter=metadata_filter
+        )
+    assert calls == [{
+        "query_embedding": [0.1] * 4, "limit_count": 5, "table_name": "evidence",
+        "kinds": ["evidence"], "metadata_filter": metadata_filter,
+    }]
+
+
 def test_rest_searcher_forwards_kinds_to_client():
     calls = []