The $12,000 Typo: Why Your Multi-Agent DAG Is Silently Evicting KV-Caches on Every Turn

Provider prompt caching can slash your LLM bills by 90%, but in multi-agent frameworks like LangGraph, inserting a dynamic timestamp in the wrong position silently destroys KV-cache reuse. Here is the canonical prefix layout that fixes it.

Written and maintained by Hassan Nazir, Forward Deployed Engineer and Applied AI practitioner.