OpenAI has expanded access to the massive context window of GPT-5.6 Sol in Codex, giving developers the ability to work with significantly larger codebases, files and conversation histories during a single coding session.
OpenAI’s official specifications confirm that GPT-5.6 Sol has a 1.05 million-token context window. This means the model can process a very large amount of information within one request, including source code, project files, instructions, previous messages and tool results.
A context window is essentially the amount of information an AI model can consider at once. For coding assistants, a larger context window can be especially useful because modern software projects often contain thousands of files, extensive documentation and long development histories.
With a 1.05 million-token context window, GPT-5.6 Sol can handle much larger project contexts than models with smaller limits. This can reduce the need for developers to repeatedly summarize files or remove older information simply to make room for new instructions.
The improvement is particularly relevant to Codex, OpenAI’s coding-focused environment. GPT-5.6 Sol is designed for complex coding and long-running engineering workflows, including work involving real codebases and tool use. OpenAI says GPT-5.6 Sol is its strongest coding model and has achieved leading results on coding evaluations such as Terminal-Bench 2.1 and DeepSWE.
For developers, the larger context window can make it easier to ask an AI assistant to understand a project as a whole rather than focusing on isolated snippets. A developer could provide large sections of a codebase, supporting documentation and previous work while maintaining more of the relevant context during the task.
This can be valuable when debugging complicated applications. Problems in one part of a project may depend on code, configuration or dependencies located elsewhere, making broader project context important for identifying the underlying issue.
Large context can also help with major refactoring projects. Instead of repeatedly explaining how different components interact, developers can provide more of the existing project and allow the model to analyze relationships across a larger portion of the codebase.
OpenAI’s current model documentation lists GPT-5.6 Sol with a 1,050,000-token context window and a maximum output capacity of 128,000 tokens. The model also supports tools including file search, code interpreter, hosted shell, computer use and apply-patch workflows.
The expanded context capability does not mean developers will always need to load an entire project into every request. Efficient context management can still improve performance and reduce unnecessary token usage. OpenAI has also highlighted smarter context management as part of the GPT-5.6 engineering work.
GPT-5.6 Sol is available in Codex for eligible ChatGPT plans, while access varies by subscription and product. OpenAI says Plus, Pro, Business and Enterprise users can access Sol in Codex, while Free and Go users receive access to GPT-5.6 Terra there.
The move represents another step toward AI coding systems that can work with increasingly large and complex software projects. As development teams rely more heavily on AI for debugging, implementation, code review and long-running engineering tasks, the ability to retain more project context could become an increasingly important advantage.
