/**
 * @internal — not part of the public agentfootprint API. Imported only
 * by RunStepRecorder. Subject to change without notice; do not import
 * via deep paths.
 *
 * ForkTracker — owns the bookkeeping for parallel-fork emission and
 * merge-step detection. Extracted from RunStepRecorder per Convention 1
 * (one purpose per recorder/state machine).
 *
 * Responsibilities (and ONLY these):
 *   1. Coalesce repeated `onFork` events for the same parent (race-safe
 *      via parent+runtimeStageId key).
 *   2. Track which child branches belong to which parent fork.
 *   3. Track which branches have exited; signal "merge ready" when ALL
 *      branches of a fork have exited.
 *
 * What it does NOT own:
 *   - Storage (the recorder writes RunSteps to its SequenceStore).
 *   - Run-boundary detection (the recorder's runIdGuard wipes this
 *     tracker via `clear()`).
 *   - Any other state machine.
 */
export interface ForkRegistration {
    /** True if this is a NEW fork; false if the same fork was already seen
     *  (caller should suppress duplicate emission). */
    readonly fresh: boolean;
}
export interface MergeReady {
    /** All branch IDs of the now-fully-exited fork, in the order they
     *  were originally registered. */
    readonly branches: readonly string[];
}
export declare class ForkTracker {
    /** Per-parent: the ordered list of child branch IDs registered. */
    private readonly branches;
    /** Per-parent: the set of child branch IDs that have exited so far. */
    private readonly exited;
    /** Reverse index: child branch ID → its parent fork. */
    private readonly childToParent;
    /** Set of `${parent}@${runtimeStageId}` keys already registered, to
     *  coalesce repeated onFork events. */
    private readonly emittedKeys;
    /**
     * Register a new fork. If the same fork (by parent+runtimeStageId)
     * was already registered, returns `{ fresh: false }` and the caller
     * should suppress emission. Otherwise registers all child branches
     * and returns `{ fresh: true }`.
     */
    registerFork(parent: string, runtimeStageId: string, children: readonly string[]): ForkRegistration;
    /** True if this child belongs to a tracked fork (used to suppress
     *  sequential-emission for fork-branch entry events). */
    isForkChild(childSubflowId: string): boolean;
    /**
     * Record a fork-branch exit. If this completes the fork (all branches
     * have exited), returns `{ branches }` so the caller can emit a merge
     * step. Returns `undefined` if not yet complete or not a fork branch.
     */
    recordChildExit(childSubflowId: string): MergeReady | undefined;
    clear(): void;
}