{
      "name": "fair-lending-disparity-audit",
      "domain": "Consumer Lending & Fair Lending",
      "title": "Fair Lending Disparity Audit",
      "spec_version": "0.8.0",
      "wave": 39,
      "description": "Gated two-step chain for fair lending disparate impact audit. Step 1 computes the HMDA rate spread and classifies reportability. Step 2 computes disparate impact metrics from aggregate approval counts (4/5ths rule, z-statistic, standardised mean difference). Gate: adverse_impact_ratio < 0.8 exits to remediation path (4/5ths rule violation). All inputs are aggregate counts only. ZERO PII BY CONSTRUCTION.",
      "composer_url": "https://ainumbers.co/chaingraph/chains/fair-lending-disparity-audit.html",
      "regulatory_refs": [
        "29 CFR §1607.4(D) (EEOC 4/5ths adverse impact rule)",
        "12 CFR Part 1003 (HMDA/Reg C)",
        "FFIEC Rate Spread methodology (APR minus APOR)"
      ],
      "steps": [
        {
          "tool_id": "art-230-compute-hmda-rate-spread",
          "handoff": "HMDA rate spread and reportability classification. Passes to disparity metrics computation."
        },
        {
          "tool_id": "art-229-compute-disparity-metrics",
          "handoff": "Adverse impact ratio, z-statistic, standardised mean difference from aggregate counts. Gate: AIR < 0.8 triggers remediation flag.",
          "gate": {
            "input": "/adverse_impact_ratio",
            "rules": [
              {
                "op": "lt",
                "value": 0.8,
                "next": "end"
              }
            ],
            "default": "end",
            "gate_policy": "review_required"
          }
        }
      ]
    }