They even give this over the API now:

│ https://openrouter.ai/api/v1/chat/completions model: stealth/ox-alpha auth: OPENROUTER_API_KEY status: 404 Not Found response: {"error":{"message":"Thank you for participating in the Stealth Ox Alpha testing period. This model was ZAI's GLM-5.3 Flash.

│ Use it now: https://openrouter.ai/z-ai/glm-5.3-flash","code":404},"user_...":"}

Yeah, made me suspicious of how well the Ox Alpha was performing that it wasn't some 'new group' making the model.