/**
 * First Message Variant Gate
 *
 * Tracks new sessions to apply variants only on the first message.
 * Prevents variants from being applied to forked/child sessions.
 */
type SessionInfo = {
    id?: string;
    parentID?: string;
};
/**
 * Creates a gate that tracks which sessions need variant applied on first message
 */
export declare function createFirstMessageVariantGate(): {
    /**
     * Mark a newly created session as pending variant application
     * Only marks non-child sessions (no parentID)
     */
    markSessionCreated(info?: SessionInfo): void;
    /**
     * Check if this session should have variant overridden
     */
    shouldOverride(sessionID?: string): boolean;
    /**
     * Mark variant as applied for this session
     */
    markApplied(sessionID?: string): void;
    /**
     * Clear session from tracking (on session delete)
     */
    clear(sessionID?: string): void;
};
export type FirstMessageVariantGate = ReturnType<typeof createFirstMessageVariantGate>;
export {};