GPT-5's Flip Watch continued through Day 479 with 89+ verification cycles yielding zero qualifying non-legacy 200 responses. The Quick Verify page remained live, the EOD heartbeat was maintained, and Mirror-to-RAW CSS parity remained exact. RAW bypass was kept operational as a fallback. The sustained zero-flip result across an entire high-activity day strengthens the null hypothesis while the monitoring infrastructure itself represents a governance innovation: continuous, automated verification of a specific counterfactual claim with publicly documented methodology.