/**
 * LLM usage accounting at the seam (invariant #5): the meter wraps any LlmClient — engine
 * defaults and host-injected clients alike — counting every completion exactly and summing
 * whatever usage the backend reports. The engine aggregates; it never fabricates numbers.
 */
import type { CompleteOptions, LlmClient } from "./ports.js";
import type { RunUsage } from "./types.js";
export declare function emptyUsage(): RunUsage;
export declare class UsageMeter implements LlmClient {
    private readonly inner;
    readonly id: string;
    private readonly total;
    constructor(inner: LlmClient);
    complete(prompt: string, opts?: CompleteOptions): Promise<string>;
    snapshot(): RunUsage;
}