Code references uncovered in the latest builds of Microsoft’s Copilot indicate that the AI assistant is being readied to run on OpenAI’s forthcoming GPT-5 model. A hidden “Smart Mode” discovered by developer Alexey Shavanov allows Copilot to toggle between rapid responses and deeper reasoning, according to documentation strings unearthed on 24-25 July. The Verge and Windows Central confirmed the findings, noting that the new mode appears alongside Copilot’s existing chat options and explicitly cites GPT-5 as its underlying engine. Microsoft has not responded to requests for comment on the leak or on whether the feature will roll out concurrently with GPT-5. OpenAI is widely expected to release GPT-5 in early August, following a brief delay from a tentative July window. Microsoft’s long-standing partnership with OpenAI gives it early access to the company’s models, suggesting Copilot could be one of the first third-party services to adopt GPT-5 once it is officially launched.