export declare function checkStale(tool: string, input: string | null, taskCompletedAt?: string | null): 'ok' | 'stale' | 'unknown';
export interface ActivityEntry {
    tool: string;
    cmd: string | null;
    result: string | null;
    status: 'ok' | 'stale' | 'unknown';
    reusable: boolean;
}
export interface ActivityLogResult {
    threadId: string;
    agentId: string;
    lookback: number;
    entries: ActivityEntry[];
    totalEntries: number;
    truncated: boolean;
}
export declare function buildActivityLogByTask(opts: {
    threadId: string;
    agentId: string;
    lookback: number;
    maxEntryChars?: number;
    decayRate?: number;
}): Map<string, string>;