import type { XopcSessionDiskEntry } from './xopc-session-disk-entry.js';
export type SessionsJsonStatsPatch = {
    messageCount: number;
    estimatedTokens: number;
    lastTurnAt: number;
};
export declare function buildSessionsJsonStatsPatch(messageCount: number, estimatedTokens: number): SessionsJsonStatsPatch;
/** Apply stats + timestamps to a single sessions.json entry (in-memory patch). */
export declare function patchSessionsJsonEntryStats(entry: XopcSessionDiskEntry, stats: SessionsJsonStatsPatch): void;
export declare function isAppendOnlyLlmTranscriptMessage(message: unknown): boolean;
/** Increment stats for a single appended LLM row (hot path). */
export declare function incrementSessionsJsonStatsForAppend(entry: XopcSessionDiskEntry, opts?: {
    tokenDelta?: number;
}): void;
