/**
 * @file
 *
 * Pure builders for the diagnostic message describing an auto-started child
 * process (the Android emulator or the Appium server) that failed during
 * startup, appending the captured output tail when available.
 *
 * A startup fails two ways — the process **dies**, or it **hangs** past a
 * budget — and the captured tail is equally the explanation in both. So the
 * tail-appending half is its own export, used by the timeout throws that once
 * reported only the budget they blew.
 *
 * Kept separate from the integration-only `transport-factory` (excluded from
 * unit tests) so the message formatting stays unit-testable — the launchers
 * themselves spawn real processes.
 */
/**
 * Parameters for {@link appendProcessOutputTail}.
 */
export interface AppendProcessOutputTailOptions {
    /**
    The captured stdout+stderr tail (empty when none was captured).
     */
    readonly output: string;
    /**
    Label for the captured output section (e.g. `"Emulator output"`).
     */
    readonly outputLabel: string;
}
/**
 * Parameters for {@link buildProcessExitMessage}.
 */
export interface BuildProcessExitMessageParams {
    /**
    The process's exit / spawn-failure details.
     */
    readonly exitInfo: ProcessExitInfo;
    /**
    The captured stdout+stderr tail (empty when none was captured).
     */
    readonly output: string;
    /**
    Label for the captured output section (e.g. `"Emulator output"`).
     */
    readonly outputLabel: string;
    /**
    Human-readable subject of the process (e.g. `"Android emulator"`).
     */
    readonly subject: string;
}
/**
 * Details of a spawned child process that has exited or failed to spawn.
 *
 * A normal exit sets `code`/`signal` (exactly one is non-`null`); a spawn
 * failure (e.g. `ENOENT` for a missing binary) leaves both `null` and sets
 * `spawnError` to the failure message.
 */
export interface ProcessExitInfo {
    /**
    Exit code, or `null` when terminated by a signal or when it failed to spawn.
     */
    readonly code: null | number;
    /**
    Terminating signal, or `null` when it exited normally or failed to spawn.
     */
    readonly signal: NodeJS.Signals | null;
    /**
    The spawn-failure message when the process never started (e.g. `ENOENT`), otherwise absent.
     */
    readonly spawnError?: string;
}
/**
 * Appends a process's captured output tail to a message, when there is one.
 *
 * Split out of {@link buildProcessExitMessage} so the **timeout** failures can
 * carry the tail too. A process that dies gets its output attached; one that
 * hangs used to get `No new emulator device appeared within 300000ms.` and
 * nothing else — even though the line that explains it (`FATAL | Running
 * multiple emulators with the same AVD is an experimental feature`) had already
 * been captured. The emulator writing its own diagnosis is worth nothing if the
 * harness reads it on only one of the two ways a startup can fail.
 *
 * @param message - The failure message to extend.
 * @param params - The captured tail and its label.
 * @returns The message, with the tail appended when non-empty.
 */
export declare function appendProcessOutputTail(message: string, params: AppendProcessOutputTailOptions): string;
/**
 * Builds a descriptive error message for an auto-started child process that
 * exited (or failed to spawn) during startup, appending the captured output
 * tail when available.
 *
 * @param params - The subject, exit details, and captured output.
 * @returns A human-readable error message.
 */
export declare function buildProcessExitMessage(params: BuildProcessExitMessageParams): string;