Looks like the Quasar and Optimus stealth models on Openrouter were in fact GPT-4.1. This is what I get when I try to access the openrouter/optimus-alpha model now:

    {"error":
        {"message":"Quasar and Optimus were stealth models, and 
        revealed on April 14th as early testing versions of GPT 4.1. 
        Check it out: https://openrouter.ai/openai/gpt-4.1","code":404}