/**
 * @license
 * Copyright 2026 Steven Roussey <sroussey@gmail.com>
 * SPDX-License-Identifier: Apache-2.0
 */
import type { RunEvent } from "./RunEventTypes";
export interface RunEventSink {
    emit(event: RunEvent): void;
    /** Resolves once the bytes are flushed — the parent reads what we wrote. */
    close(): Promise<void>;
}
/** Env var a parent process sets to ask its child for a machine-readable run. */
export declare const RUN_EVENTS_ENV = "WORKGLOW_RUN_EVENTS";
/**
 * Env var naming where answers to the run's human prompts arrive.
 *
 * Its own descriptor rather than stdin: stdin belongs to the command being run,
 * and a run started with stdin closed (`< /dev/null`, a service manager, a CI
 * job) must not die because the answers reader saw EOF.
 */
export declare const RUN_ANSWERS_ENV = "WORKGLOW_RUN_ANSWERS";
/**
 * Installs the process-wide sink.
 *
 * Every failure here is swallowed: the channel is a reporting side-channel, and
 * a run that would have succeeded must not die because the thing watching it
 * went away — a parent closing a pipe is an ordinary way for that to happen.
 */
export declare function installRunEventChannel(target: string): RunEventSink | undefined;
/**
 * Reads NDJSON answer lines from the descriptor the parent named. Returns a
 * stop function, or undefined when nothing is listening.
 *
 * Stop and start it freely: a descriptor the parent handed us belongs to the
 * parent and is never closed here. `fs` read streams close theirs on
 * `destroy()` even with `autoClose: false`, and a closed number is handed
 * straight back to the process — so the next `open()` (a database, a model
 * cache, the log) takes the slot, the next question reads that file instead of
 * the parent's answers, and the release after it closes that subsystem's
 * descriptor. Hence the explicit read loop.
 */
export declare function readRunAnswerLines(target: string, onLine: (line: string) => void): (() => void) | undefined;
export declare function getRunEventSink(): RunEventSink | undefined;
/**
 * Test seam: drops the installed sink so one test file cannot leak into the
 * next. The answer readers go with it — they are keyed by descriptor number,
 * and a test that closes its own fd frees that number for the next test's.
 */
export declare function resetRunEventChannelForTesting(): void;