NewsOpenAI's GPT-5.6 August update: Luna becomes ChatGPT's free default, Sol gets an effort sliderOpenAI retires GPT-5.5 Instant in ChatGPT. Free and Go users move to GPT-5.6 Luna with unlimited text chats, while Plus and Pro get a retuned GPT-5.6 Sol and a new effort slider.Daniel OkaforAug 6, 20268 min