Field note: what your LLM calls actually cost per turn from Julia (measured) + a tiny TokenMeter

Field note: what your LLM calls actually cost per turn when you drive them from Julia — and a tiny helper to see it I’ve been building an agent loop in Julia that calls an LLM each step (PromptingTools-style: a system prompt, a growing message history, and a set of tool/function schemas). The token bill was ~2x what I estimated from “prompt length”, so I instrumented every request/response and wrote down where the tokens actually went. Sharing the numbers in case they save someone a surprise in...