claudeopus5-free/Claude-Opus-5-AI-Free-Desktop ? reverse-engineered prompt

Build me a polished desktop app for Windows, macOS, and Linux that lets me use Claude Opus 5 from one simple window.

I want it to feel like a native AI chat app, with a clean setup flow, a chat area for long answers, a place to compare Opus 5 and Sonnet 5, and a built in panel that shows model info and benchmark results. It should support big context for reading repos or papers, save and search past sessions, and automatically fall back to Sonnet when Opus is busy or rate limited. Please make it feel fast, modern, and easy to use, with a nice theme and a few screens for comparing models side by side.

If anything about the model access or current docs is unclear, look up the latest info online and make sensible choices.