Zenith is probably the full GPT-5. My guess is that we'll probably see the release next week. @koltregaskes has rightly emphasized several times that new EU AI regulations will come into effect on August 1, so a release before August 1 seems extremely sensible. OpenAI is currently testing various models publicly, most likely GPT-5, mini, and Nano. So far, the initial tests have been extremely positive – the excitement is growing and growing. Therefore, my guess is that we will see both next week: GPT-5 + the open source model. That seems most plausible.