OpenAI has upgraded Auto-review in the ChatGPT app and Codex CLI from GPT-5.4 to GPT-5.6 Luna, extending its newest cost-optimized model tier into automated agentic workflows. The important development is not simply a model swap. It connects lower per-token pricing with a safety-oriented automation mechanism designed to reduce manual approval steps for low-risk work.
According to OpenAI's GPT-5.6 announcement, GPT-5.6 is available across ChatGPT, Codex, and the OpenAI API. OpenAI positions Luna as the fastest and most cost-efficient tier in the GPT-5.6 family for high-volume workloads, alongside the higher-capability Sol tier and the mid-range Terra tier.
For teams using coding agents or other repeated AI tasks, that positioning matters. Agentic systems can generate substantial token usage because they plan, call tools, inspect results, revise work, and may require approvals at several stages. A cheaper model tier can make those loops more practical, provided its capability and safety characteristics fit the task.
Luna pricing changes the economics, not every workflow equally
OpenAI lists GPT-5.6 Luna at $0.20 per million input tokens and $1.20 per million output tokens. It also formally cut Luna pricing by about 80% in its July 30, 2026 update, while Terra's price was reduced by about 20%. These published reductions support the broader case for lower-cost, high-volume use of the GPT-5.6 family.
