/** Minimal structural view of a pi AgentMessage we need for pruning. */
export interface PrunableMessage {
    role?: string;
    toolName?: string;
    toolCallId?: string;
    isError?: boolean;
    content?: unknown;
}
export interface PruneOptions {
    /** Tool results older than this many assistant turns are age-digested. */
    ageDigestTurns: number;
    /** Tool names eligible for pruning (large/replayable outputs). */
    prunableTools: Set<string>;
    /** Skip results whose text is smaller than this — pointer overhead isn't worth it. */
    minPruneChars: number;
}
export interface PruneResult {
    messages: PrunableMessage[];
    prunedCount: number;
    savedChars: number;
}
export declare const DEFAULT_PRUNE_OPTIONS: PruneOptions;
/**
 * Prune stale tool-result history. Pure: returns a new array (pruned messages
 * shallow-cloned), the count pruned, and chars removed from the request.
 *
 * Two rules, both conservative:
 *   1. Supersession — a tool result is collapsed when a LATER result shares its
 *      `toolName:target` identity (the agent holds the fresher copy).
 *   2. Age digest — a tool result older than `ageDigestTurns` assistant turns
 *      from the end is collapsed (already consumed by the model in prior turns).
 * The most-recent result per identity and everything inside the freshness
 * window are always retained.
 */
export declare function pruneHistory(messages: PrunableMessage[], opts: PruneOptions): PruneResult;