Isolate residual S/R target selection

tests/unit/test_recommendation_service.py

@@ -374,3 +374,6 @@ def test_gate_requires_confirmation_for_standalone_round_number():
     assert _gate_eligible_levels(
         [untouched, confirmed, confluent], confirmed_rounds_only=True
     ) == [confirmed, confluent]
+    assert _gate_eligible_levels(
+        [untouched, confirmed, confluent], exclude_standalone_rounds=True
+    ) == [confluent]