Docs · Model reference
down-payment
Verified · spec v1.0.0Inputs
| Field | Type | Valid domain |
|---|---|---|
| homePrice | float | 100,000 – 2,000,000 |
| downPaymentPct | float | 0.03 – 0.3 |
| currentSavings | float | 0 – 500,000 |
| monthlySavings | float | 100 – 10,000 |
| annualReturn | float | 0 – 0.12 |
All fields required. Out-of-domain values are rejected with per-field errors — never clamped. Unknown fields are rejected.
Sentinel values
monthsToGoal=600→ goal not reached within 600 months (yearsToGoal = 50 exactly)
Responses annotate these in a sentinels array with a triggered flag per run.
Live example — generated from the real engine
Request
POST /api/v1/models/down-payment
{
"homePrice": 1050000,
"downPaymentPct": 0.16,
"currentSavings": 250000,
"monthlySavings": 5100,
"annualReturn": 0.06
}Response (chart arrays compacted)
{
"ok": true,
"model": "down-payment",
"specVersion": "1.0.0",
"contractUrl": "/api/v1/models/down-payment",
"specUrl": "/api/v1/models/down-payment/spec",
"inputs": {
"homePrice": 1050000,
"downPaymentPct": 0.16,
"currentSavings": 250000,
"monthlySavings": 5100,
"annualReturn": 0.06
},
"outputs": {
"targetAmount": 168000,
"monthsToGoal": 0,
"yearsToGoal": 0,
"projectedSavings": [
250000,
256349.99999999997,
"… 599 more"
]
},
"sentinels": [
{
"field": "monthsToGoal",
"value": 600,
"meaning": "goal not reached within 600 months (yearsToGoal = 50 exactly)",
"triggered": false
}
],
"assumptions": [
"Implements model spec down-payment v1.0.0 (dual-implementation verified)."
],
"facts": [],
"record": {
"sha256": "87cf78f5487be7a0e72cc1191399c8dfd75069700cbd8712f88eef766e783ffa",
"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.