/**
 * Fee math and the numeric guards shared by the trading layer.
 *
 * Every place that touches money (RiskEngine, Portfolio, the engine's fill
 * validation, the paper adapters) validates its inputs with the SAME
 * predicates so the rule cannot drift between call sites.
 */
/** Smallest quantity difference the portfolio treats as "the same". */
export declare const QTY_EPSILON = 1e-12;
/**
 * Cash comparisons happen at sub-cent precision. Every rendered surface
 * rounds to cents, and a cash balance that has drifted to 699.6999999999999
 * after three fills must still accept an order sized to the displayed
 * $699.70 — otherwise the agent is refused with a reason that reads
 * "needs $699.70 but only $699.70 available".
 */
export declare const CASH_EPSILON_USD = 0.000001;
/**
 * A fill's fee may exceed the approved estimate by at most this much before
 * it is flagged. Half a cent: enough to absorb a venue that rounds the fee
 * to the cent when the estimate did not, small enough that a real overcharge
 * is still caught.
 */
export declare const FEE_TOLERANCE_USD = 0.005;
export declare function isPositiveFinite(n: unknown): n is number;
export declare function isNonNegativeFinite(n: unknown): n is number;
/**
 * Return `null` when `value` is a finite number satisfying `min`, else the
 * reason string every caller renders. Callers that throw wrap it in a
 * RangeError; callers that return a decision put it in `reason`.
 */
export declare function invalidNumberReason(label: string, value: unknown, min: 'positive' | 'nonNegative'): string | null;
export declare function assertNumber(label: string, value: unknown, min: 'positive' | 'nonNegative'): void;
/** Exact fee from order notional and basis points. */
export declare function bpsFee(order: {
    qty: number;
    priceUsd: number;
}, feeBps: number): number;
/**
 * Fee CEILING for `estimateFee()`: the exact bps fee rounded UP to the cent.
 * A venue that rounds its fee to the cent (up or to nearest), or computes it
 * on a cent-rounded notional, still lands at or below this number, so the
 * engine's fill-fee check is a real invariant rather than a float lottery.
 */
export declare function bpsFeeCeiling(order: {
    qty: number;
    priceUsd: number;
}, feeBps: number): number;
export declare function roundUpToCent(usd: number): number;