import { SpilloverRecord, SpilloverStore } from './spillover-store.interface.js';
export interface FsSpilloverOptions {
    storageDir?: string;
    sweepIntervalSeconds?: number;
    /** Total bytes retained on disk (default: 512MB). A single record larger than this is refused. */
    maxSizeBytes?: number;
}
/**
 * Filesystem spillover store.
 *
 * Directory mode 0o700 and file mode 0o600 are enforced on Unix. Windows ignores
 * those bits, so a shared temp directory is not private there; set `storageDir`
 * to a directory only this process can read.
 */
export declare class FsSpilloverStore implements SpilloverStore {
    private storageDir;
    private readonly explicitDir;
    private readonly maxSizeBytes;
    private readonly sweepTimer;
    private initialized;
    private usageReady;
    private currentSizeBytes;
    /** Serializes saves so two writers cannot both pass the capacity check. */
    private writeChain;
    constructor(options?: FsSpilloverOptions);
    private ensureDir;
    /**
     * Refuse a symlink. mkdir({ recursive: true }) follows one, and chmod follows
     * it too, so a planted link would receive the spilled files.
     */
    private assertRealDirectory;
    private sanitizeId;
    private getFilePath;
    getStorageDir(): string;
    getMaxSizeBytes(): number;
    getCurrentSizeBytes(): number;
    private enqueue;
    save(id: string, data: string, mimeType: string, ttlSeconds: number, sessionId?: string): Promise<SpilloverRecord>;
    private writeRecord;
    get(id: string): Promise<SpilloverRecord | undefined>;
    delete(id: string): Promise<boolean>;
    private unlinkId;
    private deleteIfStillExpired;
    cleanup(): Promise<number>;
    private cleanupNow;
    private ensureUsage;
    private fileSize;
    /** Deletes the oldest payload file, excluding the path about to be replaced. */
    private evictOldestFile;
    /** First bytes of a record. `expiresAt` is written before the payload. */
    private readExpiresAt;
    dispose(): Promise<void>;
}
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