Audit a validation for leakage: does outside ground-truth actually enter, or is everyone confirming a result no one independently produced? Goal The name is the Mandela Effect — a whole population confidently remembers something that never independently happened; a leaky validation is the same shape. Walk the 8 patterns below. checks one thing: whether a validation is independent, or whether the designer, model, and scorer are only confirming each other. Workflow 1. Identify the validation (eval / metric / experiment / holdout / "how we'll know"). Name its components — what plays model, score…