{
      "tool_id": "art-335-compute-dti-ratios",
      "tool_version": "1.0.0",
      "display_name": "DTI Ratio Calculator",
      "mcp_name": "compute_dti_ratios",
      "mandate_type": "compliance_mandate",
      "wave": 60,
      "gpu": false,
      "url": "https://ainumbers.co/chaingraph/art-335-compute-dti-ratios.html",
      "description": "Front-end (housing) and back-end (total) debt-to-income ratios per Fannie Mae Selling Guide B3-6-02 and Freddie Mac Single-Family Seller/Servicer Guide 5401.2. Classifies the back-end ratio into a standard-manual / extended-manual-compensating-factors / DU-LPA-only / exceeds-max tier and flags whether the loan is within the max DTI for the selected underwriting type (DU, LPA, or manual). Feeds art-222-agency-eligibility-matrix as one of its DTI inputs. Not check_agency_eligibility_matrix itself, which performs the full multi-check eligibility decision.",
      "input_schema_ref": "chaingraph/art-335-compute-dti-ratios.html#manifest",
      "consumes": [],
      "feeds": [
        "art-222-agency-eligibility-matrix"
      ],
      "status": "live",
      "conformance_fixtures": true,
      "compute_capability": "server",
      "compute_images": [{"system":"sha256-source","image_id":"sha256:2e686160add3cada6ff0482be86c0e368cd1680f7566f8deac31974459f9dc69","valid_from":"2026-07-10"},{"system":"risc0","image_id":"sha256:a1a0bc89b5b1febaeda3519f6dbade0fa5ac16beeb143c4e1b01689573567bc6","valid_from":"2026-07-17"}],
      "export_capability": [
        "json"
      ],
      "compute_proof_ready": "ready",
      "compute_proof": {
        "type": "ZkVmReceipt",
        "system": "risc0",
        "receiptFormat": "groth16-bn254",
        "imageId": "sha256:a1a0bc89b5b1febaeda3519f6dbade0fa5ac16beeb143c4e1b01689573567bc6",
        "seal": "GEoFE4JrgX7PmT4738g4zWH3KVV7NFpArgUPwlrYKV4t76zCwbry+1SkVQYcrCvbYsKpdFAgl6a8+IDxoWFPbCzTaEtOEuxYTmZaB2q6IQf7QhsBZ9JaZ+kkAwlLtA9fFf89gJYCc5+r9fSZUIXWIeIvAfovWXzkvWN9UbSXeFQgf7PAx7BL+XzkeAXqfsZ+1b03jiTO6NuLLG5jCTk4ZBftaqk4mNSmKqwNsKxlZg4aNHWNP/0w2Kdn4eWAo2LtGEynr3nDRTqT0EW3v3nc0YZOi2v7AmwrFjRfptuwjWUd8z3/z4DQvKKmwBsFS2IxeNUNo8vF22FQmqQV39r0GQ==",
        "journal": {
          "chaingraph_version": "0.4.0",
          "kernel_digest": "sha256:2e686160add3cada6ff0482be86c0e368cd1680f7566f8deac31974459f9dc69",
          "output": {
            "back_end_dti_pct": 30,
            "dti_tier": "standard_manual",
            "front_end_dti_pct": 22.5,
            "gross_monthly_income": 8000,
            "housing_payment_pitia": 1800,
            "max_dti_pct": 50,
            "note": "Front-end = housing payment (PITIA) / gross monthly income. Back-end = total monthly debt / gross monthly income. Tier bands are representative GSE manual-underwriting / AUS bands -- confirm against the current Selling Guide / Seller Guide and the specific AUS findings for the loan in question. Not check_agency_eligibility_matrix (art-222), which consumes this ratio as one of several eligibility checks.",
            "other_monthly_debts": 600,
            "regulatory_basis": "Fannie Mae Selling Guide B3-6-02 (Debt-to-Income Ratios); Freddie Mac Single-Family Seller/Servicer Guide 5401.2 (Debt payment-to-income ratio)",
            "total_monthly_debt": 2400,
            "underwriting_type": "du",
            "within_max": true
          }
        }
      }
    }