/**
 * The drivers of a change between two bills.
 *
 * One implementation, exported from core, because the sign convention here —
 * **positive means the bill grew**, the diff convention — has already flipped
 * once in this repository's history when restated by hand. The CLI, the MCP
 * and the web all render these rows; three inline computations of the same
 * union-and-subtract is three chances for one of them to disagree about what
 * a vanished workload contributed.
 *
 * Derived over the **union** of keys, so an appeared or vanished workload is
 * named rather than folded silently into the total: `was: null` is a key the
 * previous log did not have, `now: null` one this log no longer has. Both are
 * different statements from `$0.00`, and the renderings say which.
 */
export interface AgainstDriver {
    key: string;
    /** What this key cost in the previous log, or null when it was not there. */
    was: number | null;
    /** What it costs now, or null when it is gone. */
    now: number | null;
    /** `(now ?? 0) - (was ?? 0)` — positive means the bill grew. */
    delta: number;
}
export declare function driversBetween(before: ReadonlyArray<{
    key: string;
    usd: number;
}>, after: ReadonlyArray<{
    key: string;
    usd: number;
}>): AgainstDriver[];
//# sourceMappingURL=against.d.ts.map