OpenAI Codex now supports 1M token context for ChatGPT accounts

OpenAI's Codex coding tool now lets ChatGPT users enable a near-1.05 million token context window, previously limited to API keys. Engineer Tibo announced this update on X, applying to the GPT-5.6 Sol model. Subscribers to ChatGPT Plus or Pro can manually configure the full context in Codex, which helps keep more code and chat history during large codebase refactors or complex debugging.

Tibo noted that the default context length is optimized for performance and cost, so users should decide carefully. Enabling the large context speeds up subscription quota usage—some users say a single heavy session may drain weekly credits—so it's best to use it only when necessary.