import type { SessionSummary } from "./session-manager.js";
/**
 * Per-directory cache of session summaries, persisted next to the sessions.
 *
 * Resolving which checkpoint of a conversation is newest needs the header of
 * every session in the directory. Reading 14,600 headers took ~1.7 s and
 * ~1.5 GB peak RSS on every resume (bench/baseline/31-session-list-latency.mjs),
 * and the desktop app pays that on each project switch because it respawns the
 * sidecar. The index keeps each summary with the file's size+mtime fingerprint,
 * so a scan is one `readdir` plus a `stat` per file, and only files that changed
 * since the last scan are re-read (after vercel-labs/fx#1021).
 *
 * The index is only a cache: a missing, corrupt or foreign index is ignored and
 * rebuilt, and every entry is re-validated against the live filesystem.
 */
export type IndexedSessionSummary = SessionSummary & {
    conversationId: string;
    generation: number;
};
export declare const SESSION_SUMMARY_INDEX_FILE = ".session-index.json";
export declare class SessionSummaryIndex {
    private readonly directory;
    private readonly indexPath;
    private entries;
    private loading;
    private saving;
    constructor(directory: string);
    /**
     * Summaries for `candidates` (the directory's full candidate list, in the
     * same order). Unchanged files come from the index; changed or new ones are
     * read with `read` and the index is rewritten.
     */
    summaries(candidates: readonly string[], read: (candidate: string) => Promise<IndexedSessionSummary | null>): Promise<Array<IndexedSessionSummary | null>>;
    private load;
    /** Atomic replace; serialized so concurrent scans never interleave writes. */
    private save;
}