Pattern: Cross-Model Verification Becoming Industry Standard — GitHub Rubber Duck and Anthropic /ultrareview Arrive Same Week

GitHub Blog·medium signal

Multiple vendors independently implementing 'second opinion' review agents: GitHub uses a different model family (Sonnet primary + GPT-5.4 reviewer), Anthropic's /ultrareview uses parallel multi-agent analysis within the same family. Both activate at the same checkpoints (plan, implementation, pre-test). The convergence signals that single-model agentic coding is being recognized as structurally fragile. Builders should budget for verification passes in their token estimates.