Metering Always-On Agents in Node.js: Cost per Task Across GPT-6.1 Sol and Astra

A practical guide to instrumenting always-on Node.js agents with per-task token metering, so teams can compare real cost per task across GPT-6.1 Sol's roughly one-fifth-price tier, GPT-6 Astra, and the 300 tok/s Ultrafast path before committing to cloud-computer agent architectures.