/**
 * Dead Message Pruner — Phase 4 of Advanced Token Optimization
 *
 * Prunes provably obsolete messages in conversation history:
 * 1. Superseded errors — tool error followed by same tool succeeding on same input
 * 2. Permission exchanges — ask_user/ask_user_simple calls (purely procedural)
 *
 * Uses in-place content replacement (not message removal) to preserve
 * the tool_use/tool_result pairing required by the Anthropic API.
 */
import type { Message } from '../providers/types.js';
export interface PruneConfig {
    /** Enable superseded error pruning (default: true) */
    supersededErrors: boolean;
    /** Enable permission exchange pruning (default: true) */
    permissionExchanges: boolean;
    /** Tool names considered permission exchanges */
    permissionTools: string[];
    /** Never prune messages newer than this many turns (default: 4) */
    protectedTurns: number;
}
export declare const DEFAULT_PRUNE_CONFIG: PruneConfig;
export interface PruneResult {
    prunedCount: number;
    tokensSaved: number;
}
export interface PruneStats {
    prunedCount: number;
    tokensSaved: number;
    errorsPruned: number;
    permissionsPruned: number;
}
/**
 * Check if a tool result content string has been pruned.
 */
export declare function isPruned(content: string): boolean;
export declare class DeadMessagePruner {
    private readonly config;
    private readonly stamps;
    private stats;
    constructor(config?: Partial<PruneConfig>);
    /**
     * Register a tool result for pruning analysis.
     * Called at the same point as ObservationMasker.stamp().
     */
    stamp(toolUseId: string, toolName: string, input: Record<string, unknown>, isError: boolean, turn: number): void;
    /**
     * Prune dead messages in-place. Replaces content of dead tool_result
     * blocks with short placeholders and clears corresponding tool_use input.
     */
    prune(messages: Message[], currentTurn: number): PruneResult;
    getStats(): PruneStats;
    /**
     * Reset all state (stamps and stats). Used when clearing history.
     */
    reset(): void;
    /**
     * Get current configuration (for testing/inspection).
     */
    getConfig(): PruneConfig;
    /**
     * Identify tool_use IDs that should be pruned.
     */
    private identifyDeadMessages;
}