GPT-5.6 Luna becomes default for free ChatGPT users; desktop app lands on Linux

OpenAI's update pushes its latest model tier down to free users, a competitive response to the pressure from cheap Chinese models and Google's Gemini scale. GPT-5.6 Luna becomes the default for Free and Go tiers with unlimited text conversations — a notable move given the compute cost — plus a 'Think' button that lets users invoke extended reasoning on demand for harder questions.

Paid Plus and Pro subscribers receive GPT-5.6 Sol, which OpenAI claims delivers 68% fewer factual errors and adds a reasoning-effort slider to tune compute depth per response. Developers road-testing Sol praised its raw capability ('it blows my mind') while flagging a tendency to overengineer solutions — a recurring critique of frontier coding models.

Separately, OpenAI shipped its ChatGPT and Codex desktop app to Linux, closing a long-standing gap and courting the developer audience that skews toward Linux workstations.

Competitively, giving free users unlimited access to a near-frontier model raises the bar for rivals and pressures the freemium economics of the entire assistant market — especially as DeepSeek signals price hikes and Google touts 1 billion Gemini users. Skeptics question the sustainability of unlimited free inference at this quality tier. What to watch: whether the free-tier generosity is a temporary land-grab or a durable strategy, and independent verification of the 68%-fewer-errors claim for Sol.