Turning attribution graphs into readable circuits has always hit the same wall: a human analyst must spend hours grouping thousands of feature nodes into meaningful "supernodes" per prompt. This ICML workshop paper shows an LLM can do it as well as a human — and can do it at population scale.
The pipeline feeds auto-interpretability feature descriptions directly to an LLM, which clusters them into semantically coherent supernodes. Automated interpretability metrics — requiring no human judges — confirm the output matches human-annotated supernodes in quality. On a two-hop Capitals factual-recall task (e.g., "What country is Rome in? — Italy — What continent is Italy on?"), the pipeline recovers the intermediate-hop supernode in 97 of 100 prompts, validating that the automation preserves the interpretable structure circuit tracing was designed to expose. A proof-of-concept scales to 1000 Wikipedia attribution graphs: all annotated automatically, with an LLM judge flagging unusual computational patterns for human review — opening population-level circuit interpretability that was previously impractical.