Show HN: AgentTrafficCop – Stop AI agents from looping and burning money

AgentTrafficCop is a runtime circuit breaker for multi-agent systems that validates each handoff against a Pydantic v2 contract, fingerprints payloads with SHA-256, and trips on repeated or A↔B ping-pong payloads and step thresholds. It runs as a standalone FastAPI service with a Python SDK and LangGraph adapter, and is open source under MIT on PyPI, with a free tier covering 5 agents and 10,000 messages per month.