/**
 * Shared deadline-based polling and process-kill verification helpers for the
 * test suite. Test-only: nothing in src/ production code may import this file.
 */
export interface WaitUntilOptions {
    /** Total time to wait before failing (default 5s). */
    timeoutMs?: number;
    /** Poll interval (default 5ms). */
    intervalMs?: number;
    /** Included in the timeout error to identify the stuck condition. */
    label?: string;
}
/**
 * Poll `check` until it returns a truthy value, with a hard deadline.
 * Returns the first truthy value; throws once the deadline passes so a stuck
 * condition fails the test instead of silently falling through.
 */
export declare function waitUntil<T>(check: () => T | undefined | null | false | Promise<T | undefined | null | false>, opts?: WaitUntilOptions): Promise<T>;
/**
 * Shell command that blocks until `gate` exists, then writes `text` to
 * `marker`. Replaces fixed `sleep N; printf ...` fixtures: the child stays
 * alive (blocked on the gate) for exactly as long as the test needs, and a
 * kill can be proven by opening the gate and observing that the marker never
 * appears (see {@link expectMarkerNeverWritten}).
 */
export declare function gatedWriteCommand(gate: string, marker: string, opts?: {
    text?: string;
    append?: boolean;
}): string;
/** Open a {@link gatedWriteCommand} gate so a still-alive child can finish. */
export declare function openGate(gate: string): void;
/**
 * Prove a gated child process was killed: open the gate and verify the marker
 * still does not appear. A surviving child polls the gate every 20ms, so the
 * default 250ms settle window gives it >10x the time it would need to write.
 */
export declare function expectMarkerNeverWritten(gate: string, marker: string, settleMs?: number): Promise<void>;