Mechanism validated, reproduction PENDING. The same 0.3 mm / 900-cell sheet and seed as Increment 2, but each infected cell's virus secretion is throttled by (1−ρ) from its locally-sampled type-I IFN. The primary effect is on virus load (~halved every step); the mosaic shows the weaker-but-real effect on infected COUNT — the lesion stays more contained than the no-IFN control (n_I 53 vs 69 at step 40). ρ plateaus near ~0.55, a steady brake, not a hard block. No Fig 3B/5/7 target is claimed here.