import type { CacheBackend } from "../types.js";
/**
 * Persistent local cache using the bounded VFCACHE4 binary frame.
 *
 * Keys name files by SHA-256 and are also stored inside the frame so a digest
 * mismatch remains a cache miss. Strings are stored as UTF-16 code units to
 * preserve every ECMAScript string, including lone surrogates; the frame also
 * records the logical UTF-8 byte length used by `getWithinLimit()`.
 *
 * Cache files written by the former JSON format are intentionally ignored as
 * cold misses. Cache data is disposable, so no in-place migration is required.
 */
export declare class DiskCacheBackend implements CacheBackend {
    readonly type: "disk";
    private readonly dir;
    private readonly globCache;
    private readonly maxValueBytes;
    private readonly maxFileBytes;
    private mutationTail;
    private writesUntilExpiryPrune;
    private expiryPruneOffset;
    constructor(baseDir?: string, keyPrefix?: string, maxValueBytes?: number);
    private filePath;
    private ensureDir;
    private withMutation;
    private readFramedFile;
    private readEnvelopeWithinValueLimit;
    /**
     * Remove a cache file, but only while it still holds the expired entry.
     *
     * Dev servers and build steps share a project cache, so another process can
     * replace the pathname between the expiry check and the deletion. Deleting by
     * pathname would then remove that fresh entry. The file is claimed with an
     * atomic rename and revalidated on the claimed inode instead, and a claim
     * that turns out to hold a fresh entry is linked back under its original
     * name. Both the write-time sweep and the read-time cleanup go through this,
     * so neither can delete a write that won the race.
     */
    private removeExpiredEntryFile;
    /**
     * Drop an entry a read found expired.
     *
     * Queued on the mutation tail so it cannot interleave with this instance's
     * own writes, and so a caller can flush it by awaiting any later operation.
     */
    private expireEntry;
    private pruneExpiredEntries;
    private maybePruneExpiredEntries;
    get(key: string): Promise<string | null>;
    getWithinLimit(key: string, maximumBytes: number): Promise<string | null>;
    getRemainingTtlSeconds(key: string): Promise<number | null>;
    set(key: string, value: string, ttlSeconds?: number): Promise<void>;
    del(key: string): Promise<void>;
    delByPattern(pattern: string): Promise<number>;
}
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