import type { ModelMessage } from 'ai';
export type MessageTransformer = (messages: ModelMessage[], context: {
    turnCount: number;
    totalTokens: number;
    sessionId: string;
}) => Promise<ModelMessage[]> | ModelMessage[];
export interface ContextManagerOptions {
    maxTokens?: number;
    maxMessages?: number;
    keepSystemPrompt?: boolean;
    transformer?: MessageTransformer;
}
export interface ContextManagerContext {
    turnCount: number;
    totalTokens: number;
    sessionId: string;
    /** When provided, overrides the configured maxTokens for this turn. */
    maxTokensOverride?: number;
}
export interface ContextManager {
    beforeTurn(messages: ModelMessage[], context: ContextManagerContext): Promise<ModelMessage[]> | ModelMessage[];
}
export declare function createContextManager(options?: ContextManagerOptions): ContextManager;
export declare function createSummarizingContextManager(summarizeFn: (messages: ModelMessage[]) => Promise<string> | string, options?: {
    summarizeAfterNTurns?: number;
    maxTokensBeforeSummary?: number;
    summaryRole?: 'system' | 'user' | 'assistant';
}): ContextManager;