ChatGPT is now free and unlimited when using GPT-5.6 Luna

OpenAI updated GPT-5.6 Sol in ChatGPT to give shorter, more direct answers with fewer factual errors, and introduced a reasoning effort slider for Plus and Pro users. GPT-5.6 Luna becomes the free default with unlimited text chats and a Think button for harder questions. The API, Codex, and ChatGPT Work versions of GPT-5.6 Sol are unaffected. Internal evaluations show ~68% fewer factual errors with Sol and ~62% with Luna versus GPT-5.5 Instant. The post extracts four design patterns for developers building LLM features: answer-first responses, avoiding context re-dumping on follow-ups, grounding evaluation around dates/numbers/rules, and exposing user-controlled reasoning effort. It closes with a pitch for Appwrite as the backend layer for GPT-5.6 apps.