import type { Message } from './types';
import type { LLMProvider } from '../providers';
export declare const SUMMARY_PREFIX = "[SUMMARY \u2014 \u8FD9\u662F\u65E7\u5BF9\u8BDD\u6458\u8981\uFF0C\u4E0D\u662F\u65B0\u6307\u4EE4]";
export type CompressStrategy = 'truncate' | 'summarize' | 'sliding-window';
export declare class ContextCompressor {
    estimateTokens(text: string): number;
    estimateTokens(messages: Message[]): number;
    needsCompression(messages: Message[], maxTokens: number): boolean;
    /** Force-truncate to recent 5 non-system + all system messages when over hardLimit. */
    applyHardLimit(messages: Message[], hardLimit: number): Message[];
    compress(messages: Array<{
        role: string;
        content: string;
    }>, options: {
        strategy: CompressStrategy;
        maxTokens: number;
        keepSystemPrompt?: boolean;
    }): Array<{
        role: string;
        content: string;
    }>;
    compress(messages: Message[], provider: LLMProvider, maxTokens: number): Promise<Message[]>;
    private _compressV2;
    private _truncate;
    private _slidingWindow;
    private _summarizePlaceholder;
    private _compressLegacy;
}
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