/** A single steering instruction the user sent while a turn was already running. */
export type SteerMessage = {
    id: string;
    text: string;
    /** Epoch ms the steer was enqueued; useful for ordering/debugging. */
    at: number;
};
/**
 * In-process, per-session buffer of steering instructions.
 *
 * While an agent turn is streaming (thinking / calling tools) the user may send
 * one or more extra instructions ("steers"). Each is enqueued here by the
 * `/agent/steer` endpoint and drained by the `beforeModel` steer middleware just
 * before the next model call in the same running loop, so the model course-corrects
 * mid-turn instead of the user having to abort and restart.
 *
 * The buffer is deliberately in-process: a steer only makes sense for a turn that
 * is *currently running*, and that turn's SSE stream is held open on exactly one
 * instance/process. In a multi-instance deployment the `/agent/steer` request must
 * therefore reach the same instance running the turn (same constraint the in-memory
 * HITL cache / MemorySaver already carry when no persistent checkpointer is set).
 */
export declare class SteerBuffer {
    private readonly buffers;
    /** Enqueue a steering instruction for a session. Returns the created entry. */
    add(sessionId: string, text: string): SteerMessage;
    /** Number of steers currently buffered for a session. */
    size(sessionId: string): number;
    /** Return every buffered steer for a session and remove them from the buffer. */
    drain(sessionId: string): SteerMessage[];
    /** Discard any buffered steers for a session (e.g. when its turn ends unconsumed). */
    clear(sessionId: string): void;
}