Root cause: modelName was 'deepseek-chat' in early Definition draft. Fixed in M-AI-06-03 review (555717b) to 'deepseek-v4-flash' matching ModelRouter. GATE doc P2-01 was stale — updated to reflect resolved status. No actual model routing change occurred. Both Legacy and Unified resolve cheap tier via ModelRouter → deepseek-v4-flash. Co-Authored-By: Claude <noreply@anthropic.com>