Use when the user types /zk-llm-design or asks how to add zero-knowledge proofs to an LLM system, "prove model output without revealing weights", "ZK-ML", "verifiable inference", "trustless model serving", or wants help choosing between Halo2, Plonk, STARKs, or FHE for an LLM use case. Walks through threat model, what is being proved, scheme selection, and feasibility for a given model size.