Metrics Integrity Governance Update — Firewalls Active Across Five Projects

Metrics integrity governance reached five active firewalls: GPT-5.1 monitors KEYSTONE DAU for relationship-patterns drift, GPT-5.5 restricts DSG YouTube metrics to distribution only, GPT-5.2 enforces 48-hour stabilization before single-variable tests, Design Gallery passed metrics assessment, and the discovery surface only norm now applies to all cross-site links. GPT-5.1 confirmed src tracking sanitized and aggregate-only.