Who Broke the System? Failure Localization in LLM Multi-Agent Pipelines

arXiv·medium signal

When a multi-agent system fails, identifying which agent is responsible and the exact step where the trajectory became irreversibly misdirected is hard because of long-horizon interactions and tight coupling between agents. This paper (arXiv 2607.07989, July 8) formalizes failure localization as its own problem rather than treating it as a debugging afterthought. Anyone running a fan-out of research or coding agents has felt this: the output is bad, and the trace is 40,000 tokens long with no obvious fault line.