import type { Readable } from 'node:stream';
import type { AgentMessage } from './agent-runner.js';
export declare class StdioToolBridge {
    private stdin;
    private toolTimeoutMs;
    private emit;
    /** Invoked synchronously on a cancel frame — wired to terminate(). */
    private onCancel?;
    private pending;
    private counter;
    private closed;
    private buffer;
    private stopped;
    constructor(stdin: Readable, toolTimeoutMs: number, emit: (ev: Record<string, unknown>) => void, 
    /** Invoked synchronously on a cancel frame — wired to terminate(). */
    onCancel?: (() => void) | undefined);
    start(): void;
    private handleLine;
    /** Set when the caller sends a cancel frame; polled by the engine loop. */
    cancelRequested: boolean;
    /** Invoke a tool on the caller: emit tool_call, await tool_result, echo it. */
    call(name: string, args: Record<string, unknown>): Promise<{
        text: string;
    }>;
    /** Stop reading; fail anything still pending. */
    stop(): void;
}
export declare class UsageTracker {
    private cumulative;
    /** Running sum of every delta; `usd` stays null until a cost is reported. */
    readonly total: {
        in: number;
        out: number;
        usd: number | null;
    };
    /** `usd` is null when the runner reported no cost (unknown, never $0):
     *  a missing or non-finite `cost_usd` stays null instead of becoming 0. */
    delta(m: AgentMessage): {
        in: number;
        out: number;
        usd: number | null;
    };
}
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