import type { UpdateCheckResult } from "./types.js";
/**
 * Persistent storage for the most recent successful UpdateCheckResult
 * per registration. Survives Signal K restarts so a boat at sea that
 * powers up mid-ocean still sees its last-known-good check rather than
 * "unknown".
 *
 * The interface lets tests inject an in-memory implementation.
 */
export interface UpdateCache {
    load(): Record<string, UpdateCheckResult>;
    save(results: Record<string, UpdateCheckResult>): void;
}
/**
 * File-backed cache. Reads on construction is the caller's job (the
 * service calls load() once on startup); writes happen after each
 * successful check. Failures are non-fatal — a corrupted cache file
 * just means we start fresh on next boot.
 */
export declare class FileUpdateCache implements UpdateCache {
    private readonly path;
    private readonly debug;
    constructor(path: string, debug?: (msg: string) => void);
    load(): Record<string, UpdateCheckResult>;
    save(results: Record<string, UpdateCheckResult>): void;
}
/**
 * In-memory cache, used by tests and as a fallback when the data
 * directory is not writable.
 */
export declare class MemoryUpdateCache implements UpdateCache {
    private data;
    load(): Record<string, UpdateCheckResult>;
    save(results: Record<string, UpdateCheckResult>): void;
}
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