AI Cost Attribution: LLM Chargeback by Business Unit

TL;DR: AI invoice totals from OpenAI and Bedrock are not enough for business-unit chargeback. You need request-level identity and pricing fields captured at runtime. A gateway-centric pattern using LiteLLM or a custom proxy plus OpenTelemetry gives higher attribution accuracy than app-only logging or post-hoc invoice allocation. According to the OpenTelemetry GenAI semantic conventions, token and model attributes like gen_ai.usage.input_tokens and gen_ai.request.model should be captured consis...