/**
 * Leaper Agent - Context Engine
 *
 * Abstract base class for context management strategies, plus a
 * ConversationContext wrapper that delegates compression to an engine.
 * Translated from Python agent/context_engine.py.
 */
import type { ChatMessage } from '../types.js';
export interface ContextEngineStatus {
    lastPromptTokens: number;
    thresholdTokens: number;
    contextLength: number;
    usagePercent: number;
    compressionCount: number;
}
export declare abstract class ContextEngine {
    abstract readonly name: string;
    lastPromptTokens: number;
    lastCompletionTokens: number;
    lastTotalTokens: number;
    thresholdTokens: number;
    contextLength: number;
    compressionCount: number;
    thresholdPercent: number;
    protectFirstN: number;
    protectLastN: number;
    abstract updateFromResponse(usage: {
        prompt_tokens: number;
        completion_tokens: number;
        total_tokens: number;
    }): void;
    abstract shouldCompress(promptTokens?: number): boolean;
    abstract compress(messages: ChatMessage[], currentTokens?: number, focusTopic?: string): ChatMessage[];
    /** Called before sending messages to the LLM to check preflight compression need. */
    shouldCompressPreflight(_messages: ChatMessage[]): boolean;
    /** Returns false when the middle slice is too small to bother compressing. */
    hasContentToCompress(_messages: ChatMessage[]): boolean;
    onSessionStart(_sessionId: string, _kwargs?: Record<string, unknown>): void;
    onSessionEnd(_sessionId: string, _messages: ChatMessage[]): void;
    onSessionReset(): void;
    /** Return OpenAI-style tool schemas the engine exposes to the agent loop. */
    getToolSchemas(): unknown[];
    /** Dispatch a tool call routed to this engine. */
    handleToolCall(name: string, _args: Record<string, unknown>): string;
    getStatus(): ContextEngineStatus;
    /** Called when the active model changes so threshold can be recalculated. */
    updateModel(_model: string, contextLength: number): void;
}
/**
 * Conversation context tracker.
 *
 * Maintains the running message history and delegates compression decisions
 * and execution to an optional ContextEngine.  The engine is intentionally
 * optional so the class can be used as a plain message accumulator without
 * any compression strategy.
 */
export declare class ConversationContext {
    private messages;
    private engine;
    constructor(engine?: ContextEngine);
    /** Append a single message to the history. */
    addMessage(msg: ChatMessage): void;
    /** Return a shallow copy of the current message list. */
    getContext(): ChatMessage[];
    /**
     * Rough token estimate using the chars/4 heuristic.
     * Defaults to the stored message list when no argument is provided.
     */
    estimateTokens(messages?: ChatMessage[]): number;
    /** Ask the engine whether the current history warrants compression. */
    shouldCompress(): boolean;
    /** Run the engine's compress() in-place on the stored messages. */
    compress(focusTopic?: string): void;
    /** Discard the entire history. */
    clear(): void;
}
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