import type { ILLMProvider } from "../llm/ILLMProvider.ts";
import type { Message } from "../llm/types.ts";
/**
 * Compresses conversation context when approaching token limits.
 *
 * Estimates token usage via a heuristic (content.length / 4), then
 * summarises the middle block into a single assistant message when
 * the total exceeds a configurable threshold ratio of the context window.
 * The system prompt and last N messages are preserved verbatim.
 *
 * Used before LLM calls to prevent context overflow without losing
 * critical conversation boundaries.
 */
export declare class ContextCompressor {
    private llm;
    private thresholdRatio;
    private defaultContextWindow;
    constructor(llm: ILLMProvider, thresholdRatio?: number, defaultContextWindow?: number);
    compress(messages: Message[], modelContextWindow?: number, isSkillContentProtected?: boolean): Promise<Message[]>;
    private splitMessages;
    private compressProtected;
    private partitionProtected;
    private classifyTurn;
    private ensureValidToolSequence;
    private hasMatchingAssistant;
    private summarize;
    private estimateTokens;
}
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