The article analyzes OpenAI's GPT-6 Sol and Luna models, their benchmark performance, cost reductions, and how they enable task-based model routing in AI coding agents, including routing strategies, prompt caching, and practical integration advice.
OpenAI has moved the GPT‑5.6 Luna model to the free ChatGPT tier, removing chat‑turn limits, adding a Think button, and clarifying product layers such as Sol, Codex, Work and API, while outlining practical use‑cases, enterprise efficiency gains, and guidance for developers.
OpenAI merges fast‑answer and deep‑reasoning capabilities into GPT‑5.6 Sol for Plus/Pro users, introduces unlimited text‑only chat with GPT‑5.6 Luna for free users, adds a reasoning‑intensity slider, reports internal error‑rate cuts (68% vs Instant, 62% for Luna), and leaves Work and Codex models unchanged.
OpenAI has cut the API prices of its GPT‑5.6 Luna, Terra and Sol models by up to 80%, introduced a faster "Fast mode" for Sol, and outlined how the lower costs reshape model selection, usage patterns, and overall AI budgeting for developers.
