GPT-5.6 and Claude Sonnet 4.8 may be released in June.

     According to a leak from Pankaj Kumar, OpenAI's GPT-5.6 and Anthropic's Claude Sonnet 4.8 may be released in June. Kumar claims that a Claude Code npm update on March 31, 2026, unexpectedly revealed approximately 512,000 lines of internal debug source map, including references to Sonnet 4.8. This version may skip Sonnet 4.7, focusing on upgrades to visual understanding, code generation, instruction compliant functions, and adding a more robust inference level. GPT-5.6 is related to OpenAI's internal testing tags. The leak mentions tags such as iris-alpha, ember-alpha, and beacon-alpha appearing in the development environment, potentially corresponding to multiple GPT-5.6 variants. This version may be divided into GPT-5.6 and GPT-5.6 Pro, focusing on multi-step inference, agent workflow, front-end generation, and debugging capabilities. This leak also places the Gemini 3.5 Pro in the same timeframe, suggesting that multiple top-tier models may be updated simultaneously in June.