/**
 * Late-bound hooks so low-level services (token usage, trace recorder) can
 * feed the usage ledger without importing it (the ledger imports them).
 *
 * @module services/usage-ledger/ledger-hooks
 */
import type { TokenUsageEvent } from '../monitoring/token-usage.service.js';
/** What the ledger needs to know about a new request. */
export interface RequestMeta {
    traceId: string;
    ticketId?: string;
    requestId: string;
    title: string;
    description?: string;
    channel?: string;
    threadRef?: string;
    createdAt?: string;
}
/**
 * Register the ledger's usage observer.
 *
 * @param fn - Called after every recorded usage event; null removes it
 */
export declare function setUsageObserver(fn: ((session: string, event: TokenUsageEvent) => void) | null): void;
/**
 * Register the ledger's request observer.
 *
 * @param fn - Called when a request gets its trace; null removes it
 */
export declare function setRequestObserver(fn: ((meta: RequestMeta) => void) | null): void;
/**
 * A usage event was recorded. Never throws.
 *
 * @param session - Agent session
 * @param event - The event (trace id already stamped)
 */
export declare function notifyUsage(session: string, event: TokenUsageEvent): void;
/**
 * A request was given its trace. Never throws.
 *
 * @param meta - Request facts
 */
export declare function notifyRequest(meta: RequestMeta): void;
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