xAI quietly dropped a massive update for Grok-4-Fast today. Use Grok4-Heavy + Grok-4-Fast + Grok-Code-Fast-1 for code. Grok4 is the best model in the world right now. Reasoning Mode: Jumped from 77.5% to 94.1% completion rate. Non-Reasoning Mode: Jumped from 77.9% to 97.9%. 2M context, unified modes, and SOTA. API: $0.20/M input tokens, $0.50/M output. SuperGrok/Premium+ for unlimited. Multimodal (text + images) with built-in web/X search.