OpenChainGraph Suite · CONTRACT A3 · arch #5

Homebuyer Affordability Check

Note (dated 2026-08-04): a chain composes independent computations performed in an analytical order. No step's output is carried into the next step by the execution model; each step computes from its own declared inputs. This is true of every chain on this site, including chains whose per-step copy below reads as a data handoff.

Check the two ratios lenders check first: debt-to-income (DTI) per Fannie Mae Selling Guide B3-6-02 (ART-335) and loan-to-value (LTV) per Fannie Mae Selling Guide B2-1.1-03 (ART-336), then a session receipt aggregating the run's execution hashes (CRY-05). This shows two underwriting ratios, not a promise of approval or denial. Not financial advice.

OpenChainGraph · 3 Steps cryptographic mandate Hash-Anchored §4 chain_depth:3 Client-Side · Zero PII
Chain Topology: DTI Ratios → LTV Ratios → Session Receipt
§4 Execution Hash · Chain Definition Anchor
execution_hash:computing…
Chain Stages · 2 Steps
1 ROOT node
DTI Ratio Calculator art-335-compute-dti-ratios
Produces front_end_dti_pct and back_end_dti_pct from gross monthly income, housing payment (PITIA), and other monthly debts; classifies the back-end ratio into a DTI tier
MCP Call · compute_dti_ratios
{
  "jsonrpc": "2.0",
  "method": "tools/call",
  "params": {
    "name": "compute_dti_ratios",
    "arguments": {}
  },
  "id": 1
}
https://mcp.ainumbers.co/mcp
↓
2 NODE · D1 node
LTV/CLTV/HCLTV Ratio Calculator art-336-compute-ltv-ratios
Produces ltv_pct, cltv_pct, and hcltv_pct from appraised value, sales price, and lien amounts; applies the lesser-of-value-or-price rule
MCP Call · compute_ltv_ratios
{
  "jsonrpc": "2.0",
  "method": "tools/call",
  "params": {
    "name": "compute_ltv_ratios",
    "arguments": {}
  },
  "id": 1
}
https://mcp.ainumbers.co/mcp
↓
3 TERMINAL · D2 node
Agent-Action Audit-Trail Aggregator cry-05-agent-action-audit-trail-aggregator
Produces session_receipt_root, the Merkle root over the run's execution_hashes (final stage)
MCP Call · aggregate_execution_receipts
{
  "jsonrpc": "2.0",
  "method": "tools/call",
  "params": {
    "name": "aggregate_execution_receipts",
    "arguments": {}
  },
  "id": 1
}
https://mcp.ainumbers.co/mcp
Export Artifacts
Download the §4 chain definition artifact (hash-anchored composite JSON) or the §13.11 W3C Verifiable Credentials view. Both derive from the chain definition. No new hash is minted. Available after hash computation.

Ask your agent

Copy this paragraph into Claude, OpenClaw, or any MCP-aware agent to run this whole workflow on the server and check one field that answers a real question.

Question: I earn $8,000/month, my housing payment would be $2,200/month (PITIA), and I have $600/month in other debts. What are my DTI ratios?
Run the AINumbers MCP tool `run_chain` with {"chain":"homebuyer-affordability-check"} and read `art-335-compute-dti-ratios.back_end_dti_pct`.
Re-run with `inputs` for `art-335-compute-dti-ratios`, reusing the values that result echoed, with `housing_payment_pitia` set to 2800. Compare the same field.
Verify: call `verify_execution_hash` (https://mcp.ainumbers.co/mcp) with `claimed_hash` set to `composite_execution_hash` and the full `composite_artifact`.
Ledger, for a human re-check: https://ledger.ainumbers.co/
PII rule: send synthetic or anonymised inputs only. The MCP server runs these kernels and logs no payloads.
Chain page: https://ainumbers.co/chaingraph/chains/homebuyer-affordability-check.html