Multi-Outcome NegRisk Arbitrage Scanner

This tool scans Polymarket's NegRisk (no-risk) order books for simultaneous bids/asks across complementary outcomes that guarantee a risk-free profit. For example, if a YES on outcome A + YES on outcome B + YES on outcome C can be bought for less than $1.00 combined, or if all NO outcomes sum to more than $1.00, an arbitrage is detected. The scanner calculates exact fill amounts and accounts for gas costs and maker-taker fees. Entry executes market or limit orders across multiple outcomes simultaneously; exit is automatic at resolution. Paper-trading since April 2026 shows ~0.5-2% ROI per arbitrage opportunity with 60+ passing unit tests. Implementation uses Python asyncio, websocket streams for real-time book updates, and a React dashboard for monitoring.