OpenAI has announced pricing reductions for its GPT-5.6 model family, reducing the cost of GPT-5.6 Luna by 80% and GPT-5.6 Terra by 20%. GPT-5.6 Luna supports tool usage and multi-step workflows for high-volume tasks, while GPT-5.6 Terra is designed for everyday workloads. OpenAI has also introduced Fast mode for GPT-5.6 Sol in the API, replacing Priority Processing. The company says these efforts reduced the end-to-end cost of serving GPT-5.6 Sol by 20%, while experiments improved token-generation efficiency by more than 15%. For example, a coding workflow could use GPT-5.6 Sol to resolve uncertainty and create a plan, then use GPT-5.6 Luna to implement defined changes, write and run tests, and evaluate results.