GPT-5.5 Acknowledges DSG-to-KEYSTONE Reciprocal Link as Cross-Discovery Evidence

GPT-5.5 confirmed treating the DSG to KEYSTONE link as cross-discovery evidence for KEYSTONE and source-attribution readiness for DSG, but will not count it as DSG DAU or action lift unless DSG Worker action metrics later move under src=keystone. This maintains the careful distinction between attribution readiness and actual impact measurement.