AgentTrafficCop is a runtime circuit breaker for multi-agent systems. It sits between your agents, validates every handoff, fingerprints every payload, and trips the breaker before an agent loop empties your API budget. Version 1.0.1 is on PyPI, and it launched on Hacker News on November 2, 2026.
The problem it solves is familiar to anyone running agent teams: two agents can ping-pong feedback at each other for dozens of rounds, each round burning tokens, with no one stopping the cycle. AgentTrafficCop watches the traffic and halts the session when a loop is detected, returning structured diagnostics so your orchestrator can decide whether to halt, alert, or escalate.
Key features
- Schema shield: every handoff is validated against a strict Pydantic v2 contract before it reaches the next agent, so malformed payloads are rejected at the door.
- Loop detection: SHA-256 fingerprinting on every payload catches identical repeats and A-to-B ping-pongs, with step counters catching the rest.
- Circuit breaker: when thresholds breach, the response carries structured diagnostics with error codes like
CYCLIC_PAYLOAD_LOOP. - Open source and self-hostable: MIT-licensed, runs as a standalone FastAPI service, with 190+ tests passing in CI.
- Framework integrations: ships a LangGraph adapter and works with CrewAI, AutoGen, or raw asyncio.
- Five-line integration: wrap your orchestrator’s handoff calls with a guard and handle
LoopDetectedexceptions.
Who it is for
AgentTrafficCop is for developers running multi-agent systems in production, or even in development, where runaway loops are a real cost risk. If your agents hand off work to each other and you have ever watched a run spiral, this is the kind of guardrail that pays for itself.
Pricing
The Free plan costs $0 forever and covers up to 5 agents with 10,000 messages per month on the hosted cloud, with no credit card required. The middleware and SDK are open source and self-hostable. Pro ($49/month) and Team ($199/month) managed tiers are listed as coming soon. Pricing details are based on the official website; terms may change, so check agenttrafficcop.com for the latest.
Information based on the official AgentTrafficCop website, checked November 3, 2026.
