round 1.3: P(1)=0.7; P(2)=0.3
exact mean=1.300000; variance=0.210000
squared loss to target 1: expected=0.300000; unrounded=0.090000
ten +0.1 updates: nearest=0; SR expectation=1.000000; variance=0.900000
2-bit floor-grid expectation=1.250000
checks=PASS; report.json written
