/**
 * Coordinates the two directions of the driver-swap / prompt-turn race:
 *
 * - swap-during-turn: a swap {@link awaitActiveTurn}s so the outgoing driver is
 *   never killed while a turn is still awaiting its `prompt()`.
 * - prompt-during-swap: a prompt {@link awaitSwap}s so it binds to the fresh
 *   driver instead of one being disposed.
 *
 * A single instance is scoped to one agent server. All methods are safe to call
 * even when nothing is in flight (they resolve immediately).
 */
export declare class DriverSwapGate {
    /** Resolves when the in-flight driver recreate settles (resolve or reject). */
    private activeDriverSwap;
    /** FIFO chain; resolves once every started turn has settled. */
    private turnTail;
    /**
     * Mark a turn as in flight. Call at the real `driver.prompt()` dispatch — not
     * earlier — so a same-handler restart (e.g. restaging skills before the turn)
     * cannot self-deadlock by awaiting the very turn that spawned it. Returns an
     * idempotent `endTurn`; call it in a `finally` around the dispatch.
     */
    beginTurn(): () => void;
    /**
     * Await any in-flight turn before tearing a driver down. Awaits the FIFO tail
     * (not a single "latest turn" field) so an earlier turn that outlives a later
     * one still holds the swap off — the tail resolves only once every started
     * turn has settled. Never throws: a rejected turn is still a settled turn, and
     * the swap may proceed (the driver is idle either way).
     */
    awaitActiveTurn(): Promise<void>;
    /**
     * Register the in-flight recreate promise so concurrent prompts defer to it.
     * Auto-clears when `recreate` settles (resolve OR reject) so a failed recreate
     * never blocks prompts forever.
     */
    beginSwap(recreate: Promise<void>): void;
    /**
     * Await the in-flight swap before reading the live driver. Re-checks in a loop
     * so a second swap starting during the wait is also awaited.
     */
    awaitSwap(): Promise<void>;
}
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