import { type ProactiveCandidate, type UsageLike } from './headroom.js';
/**
 * Move off an account BEFORE it runs out, rather than waiting to hit the wall.
 *
 * Usage is cheap to read (a plain GET, no tokens), so a run can watch its own
 * headroom and hand the session to a roomier account while everything is still
 * working. The switch itself goes through the normal request path, which means
 * a live session moves in place and keeps its conversation.
 */
export interface ProactiveDeps {
    /** Accounts that could be switched to, with their current eligibility. */
    candidates: () => ProactiveCandidate[];
    /** The account in use right now, or null when there is none. */
    current: () => string | null;
    /** Refresh + return usage per account (TTL-cached upstream). */
    usage: () => Promise<Map<string, UsageLike>>;
    /** Ask for the switch (writes a switch request / sets the active account). */
    requestSwitch: (account: string, reason: string) => void;
    /** Percent at which an account is considered "nearly out" (0 disables). */
    thresholdPercent: number;
    /** Require this many points more headroom on the target (anti-flap). */
    hysteresisPercent?: number;
    /** Do not switch again within this window. */
    cooldownMs?: number;
    /** Restrict the decision to one model's window (e.g. "Fable"). */
    model?: string;
    now?: () => number;
    onError?: (error: Error) => void;
}
export interface TickResult {
    /** What happened, for logs and the `ccx auto` exit code. */
    outcome: 'switched' | 'no-switch' | 'cooldown' | 'disabled' | 'error';
    account?: string;
    reason: string;
}
/**
 * One decision cycle. Safe to call at any time: it never throws, and anything
 * it cannot establish (usage unknown, no current account) results in no switch.
 */
export declare function proactiveTick(deps: ProactiveDeps, state?: {
    lastSwitchAt?: number;
}): Promise<TickResult>;
export interface ProactiveRunner {
    stop(): void;
}
/**
 * Run {@link proactiveTick} on an interval for the lifetime of a session. The
 * timer is unref'd so it can never keep the process alive on its own.
 */
export declare function startProactiveRotation(deps: ProactiveDeps, intervalMs: number): ProactiveRunner;