One v3 bot suddenly came in net-positive with a gross Sharpe near +13 — implausible. Our money-printer guard (the leak hunter we keep armed on every result) ran the checks before we believed it.
Root cause: a contemporaneous-order-flow lookahead. The flow feature aggregated the SAME window whose forward return the bot traded — so it was 'seeing' the move that already happened. Classic leak.
Lagged to the last completed window (the honest way), the bot collapsed straight back to net-negative — the efficient floor, restored. The guard worked; nothing fake shipped.
This is the trust asset the entire picks/AI-tools category lacks: we publish our calibration AND the leak we caught in our own work. A tout never shows you the bug.