occydefi/agent-derivatives — reverse-engineered prompt

Build me a small JavaScript API for a Solana Arena skill called agent derivatives. The idea is that users can trade futures based on how AI agents perform in competitions, so the service should feel like the backend for creating simple markets, viewing available agent futures, placing a trade, checking open positions, and settling results when an agent performance score is reported.

Keep it lightweight and easy to run locally with npm. Include a basic health endpoint like the README shows, clear JSON responses, simple validation, and enough mock data so I can test the whole flow without needing a real wallet or live Solana connection yet. If there are already files in the repo, work with them instead of replacing everything blindly.

Please make it clean, documented, and ready to connect to Solana later. Add a short README update with how to start it and a couple curl examples.