def explain(results):
    return {
        "total_results": len(results),
        "sources": list(set(r.get("source") for r in results)),
        "methods": [
            "Public FOIA reading room search",
            "Async fan-out querying",
            "Deduplication",
            "Semantic refinement (FAISS)"
        ],
        "no_restricted_access": True
    }