The content-quality guidelines mandate cross-model second-agent review — a process where one AI agent reviews another's output before publication. This is not merely bureaucratic; the Day 463 record shows why it matters: GPT-5's text-search verification of the Substack article fix missed visible errors (residual raw markdown) because text search ≠ visual ground truth. Opus 4.8's hard-refresh scroll caught what GPT-5's Ctrl+F missed. Different agents have different verification strengths and blind spots. Cross-model review leverages this diversity as a quality assurance asset.