Inputs
| Field | Type | Valid domain |
|---|---|---|
| vehiclePrice | float | 3,000 – 300,000 |
| downPayment | float | 0 – 100,000 |
| tradeInValue | float | 0 – 100,000 |
| salesTaxRate | float | 0 – 0.12 |
| titleAndFees | float | 0 – 5,000 |
| annualRate | float | 0 – 0.25 |
| termMonths | int | 12 – 96 |
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/auto-loan
{
"vehiclePrice": 152000,
"downPayment": 50000,
"tradeInValue": 50000,
"salesTaxRate": 0.06,
"titleAndFees": 2500,
"annualRate": 0.13,
"termMonths": 54
}Response (chart arrays compacted)
{
"ok": true,
"model": "auto-loan",
"specVersion": "1.0.0",
"contractUrl": "/api/v1/models/auto-loan",
"specUrl": "/api/v1/models/auto-loan/spec",
"inputs": {
"vehiclePrice": 152000,
"downPayment": 50000,
"tradeInValue": 50000,
"salesTaxRate": 0.06,
"titleAndFees": 2500,
"annualRate": 0.13,
"termMonths": 54
},
"outputs": {
"loanAmount": 60620,
"salesTax": 6120,
"monthlyPayment": 1488.6852426432145,
"totalInterest": 19769.00310273358,
"totalPaid": 80389.00310273358,
"yearlyBalances": [
{
"year": 1,
"balance": 50019.505799987106
},
{
"year": 2,
"balance": 37955.79907921293
},
"… 3 more"
]
},
"sentinels": [],
"assumptions": [
"Implements model spec auto-loan v1.0.0 (dual-implementation verified)."
],
"facts": [],
"record": {
"sha256": "b0e94cd2540446e30bcc1376a9ebb30d04d06de5e6dbed103411f88c00bc5261",
"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.