/**
 * Usage policy: how much room an account has left, and when to move off it
 * BEFORE it hits the wall.
 *
 * A subscription has several windows running at once (a 5-hour session window, a
 * weekly all-models window, and a weekly window per model such as Fable). The
 * one that runs out first is the "binding" window, so that is what decides both
 * how healthy an account is and when to rotate. Judging by the 5-hour number
 * alone is exactly how an account looks fine while its weekly model window is
 * what actually stops you.
 */
export interface UsageLike {
    /** 0..1 utilization, or null when unknown. */
    fiveHour: number | null;
    sevenDay: number | null;
    /** When each account-wide window resets, so a spent one can be seen to lift. */
    fiveHourReset?: number | null;
    sevenDayReset?: number | null;
    models?: Array<{
        name: string;
        utilization: number;
        resetsAt?: number | null;
    }> | null;
}
/**
 * The worst (binding) utilization across every window still in force, or null
 * when nothing is known.
 *
 * Windows whose reset has passed are skipped rather than counted: their number
 * describes a limit that has already lifted, and treating it as live is how an
 * account gets abandoned for a cap it no longer has.
 */
export declare function bindingUtilization(usage: UsageLike | undefined | null, model?: string, now?: number): number | null;
/** Remaining room (0..1) on the binding window, or null when unknown. */
export declare function headroom(usage: UsageLike | undefined | null, model?: string, now?: number): number | null;
export interface ProactiveCandidate {
    name: string;
    enabled: boolean;
    loggedIn: boolean;
    capped?: boolean;
}
export interface ProactiveInput {
    /** The account in use right now. */
    current: string;
    candidates: ProactiveCandidate[];
    /** Account name -> its usage snapshot. */
    usage: Map<string, UsageLike>;
    /** Move off an account once its binding window reaches this percent (0..100). */
    thresholdPercent: number;
    /**
     * Only move when the target has at least this many percentage points more
     * room than the current account, so two similar accounts cannot ping-pong.
     */
    hysteresisPercent?: number;
    /** Restrict the decision to one model's window (e.g. "Fable"). */
    model?: string;
    /** Evaluated against this instant, so a window that has reset is not a limit. */
    now?: number;
}
export interface ProactiveDecision {
    switchTo: string | null;
    reason: string;
}
/**
 * Decide whether to move off the current account before it runs out. Fail-safe
 * by construction: unknown usage never triggers a switch, and a target is only
 * chosen when it is both under the threshold and meaningfully roomier.
 */
export declare function decideProactiveSwitch(input: ProactiveInput): ProactiveDecision;