Braintrust founder Ankur Goyal lays out Topics, the intelligence layer for analyzing production agent traces at scale where million-token traces with hundreds of spans break every standard NLP tool that expects uniform document shapes. Inspired by Anthropic's Clio paper, the pipeline runs preprocess to facet to embed to cluster to name to classify, with the LLM summary doing the one job that makes the rest tractable since the raw trace never has to fit in an embedding model's context window.