/**
 * Max-affordable-home-price under the standard 28/36 DTI rule.
 *
 * Hoisted from every realty cohort MCP — each one (`zillow-mcp`,
 * `redfin-mcp`, `compass-mcp`, `homes-mcp`, `onehome-mcp`) ships a
 * `*_calculate_affordability` tool whose math is identical to the
 * digit. zillow's 240 extra lines are explanation strings and
 * bucket breakdowns — trivial to layer as a portal-specific wrapper
 * on top of this pure core.
 *
 * The math: invert PMT against two constraints, pick the binding one.
 *
 *   front-end cap  =  income * front_end_dti
 *   back-end cap   =  income * back_end_dti − monthly_debts
 *   max_piti       =  min(front, back)   ← binding constraint
 *
 *   PITI = P&I + tax + insurance + HOA
 *        = loan * factor + price * (tax/$) + ins + hoa
 *        = loan * factor + (loan + down) * (tax/$) + ins + hoa
 *
 *   Solve for `loan`:
 *
 *     max_piti − ins − hoa − down*(tax/$)
 *   ────────────────────────────────────────  =  loan
 *           factor + (tax/$)
 *
 *   max_home_price = loan + down_payment
 *
 * where `factor = r(1+r)^n / ((1+r)^n − 1)` is the standard PMT
 * coefficient for monthly rate `r` and term-months `n`. The `r === 0`
 * branch falls back to straight-line amortization (`1/n`) to avoid a
 * 0/0.
 *
 * Pure function — no I/O, no portal SDK. Cohort MCPs wrap with their
 * own `*_calculate_affordability` tool description string.
 */
export interface AffordabilityInput {
    /** Borrower's gross monthly income, dollars. Must be > 0. */
    monthly_income: number;
    /** Recurring monthly debt service (car / student / minimum CC). Default 0. */
    monthly_debts?: number;
    /** Cash down, dollars. Must be >= 0. */
    down_payment: number;
    /** Annual interest rate as a percent (e.g. `6.5` for 6.5%). Must be >= 0. */
    interest_rate: number;
    /** Loan term in years. Default 30. */
    loan_term_years?: number;
    /** Annual property tax as a percent of home price (e.g. `1.1`). Default 1.1. */
    property_tax_rate?: number;
    /** Annual homeowners insurance premium, dollars. Default 0. */
    insurance_annual?: number;
    /** Monthly HOA dues, dollars. Default 0. */
    hoa_monthly?: number;
    /** Front-end (housing / income) DTI cap as decimal. Default 0.28. */
    front_end_dti?: number;
    /** Back-end ((housing + debts) / income) DTI cap as decimal. Default 0.36. */
    back_end_dti?: number;
}
export interface AffordabilityResult {
    max_home_price: number;
    max_monthly_piti: number;
    binding_constraint: 'front_end' | 'back_end';
    monthly_principal_interest: number;
    monthly_property_tax: number;
    monthly_insurance: number;
    monthly_hoa: number;
    loan_amount: number;
    down_payment: number;
    front_end_dti_used: number;
    back_end_dti_used: number;
}
/**
 * Solve for the maximum home price the borrower can afford under the
 * 28/36 DTI rule (or custom DTI caps via `front_end_dti` / `back_end_dti`).
 *
 * @throws if `monthly_income <= 0`, `down_payment < 0`, or `interest_rate < 0`.
 */
export declare function calculateAffordability(input: AffordabilityInput): AffordabilityResult;