Inputs
| Field | Type | Valid domain |
|---|---|---|
| homePrice | float | 50,000 – 3,000,000 |
| downPaymentPct | float | 0.03 – 0.19 |
| annualRate | float | 0.005 – 0.15 |
| termMonths | int | 120 – 480 |
| pmiMonthly | float | 20 – 1,000 |
| cancelLtv | choice | 0.80 | 0.78 |
All fields required. Out-of-domain values are rejected with per-field errors — never clamped. Unknown fields are rejected.
Live example — generated from the real engine
Request
POST /api/v1/models/pmi-removal
{
"homePrice": 1525000,
"downPaymentPct": 0.11,
"annualRate": 0.08,
"termMonths": 300,
"pmiMonthly": 510,
"cancelLtv": "0.80"
}Response (chart arrays compacted)
{
"ok": true,
"model": "pmi-removal",
"specVersion": "1.0.0",
"contractUrl": "/api/v1/models/pmi-removal",
"specUrl": "/api/v1/models/pmi-removal/spec",
"inputs": {
"homePrice": 1525000,
"downPaymentPct": 0.11,
"annualRate": 0.08,
"termMonths": 300,
"pmiMonthly": 510,
"cancelLtv": "0.80"
},
"outputs": {
"loanAmount": 1357250,
"monthlyPayment": 10475.48,
"monthsToRemoval": 75,
"totalPmiPaid": 38250,
"equityAtRemoval": 306037.9051067913
},
"sentinels": [],
"assumptions": [
"Implements model spec pmi-removal v1.0.0 (dual-implementation verified)."
],
"facts": [],
"record": {
"sha256": "96677c8278ce045a609fb2805281508f786be7b8396ce33c8b2c807ce51da867",
"fields": [
"model",
"specVersion",
"inputs",
"outputs"
],
"howToVerify": "Store this record with any advice or agent output built on these numbers. To verify later: build {model, specVersion, inputs, outputs} from the stored response, serialize as JSON with object keys sorted recursively (no whitespace), and SHA-256 it — a match proves the numbers came from this spec version with these inputs, unaltered."
},
"disclaimer": "Illustrative planning model, not financial advice. Outputs follow the published model spec exactly; read the spec for assumptions and exclusions before relying on any number."
}This example is executed against the production engine when the page builds — it cannot drift from the API's real behavior.