/**
 * src/cache.ts — Local filesystem cache paths + tiny JSON helpers.
 *
 * Ownership layout (everything under `~/.skillfm/beacon-mcp/`):
 *   - rules-v{N}.json    cached brain rule snapshot (stale-while-revalidate)
 *   - user-prefs.json    UserPreferences from contract §9
 *   - session-cache.db   suggestion dedupe + frequency-limit ledger (sqlite stub)
 *   - config.json        agent token + apiBaseUrl (read by config.ts)
 *
 * Phase 0 keeps everything as JSON files — no real sqlite dependency to keep
 * the npm tarball minimal. Session dedupe lives in-memory for now.
 *
 * TODO Week 5:
 *   - Open session-cache.db with `better-sqlite3` (lazy import to avoid
 *     making it a hard dep on agents that never use frequency limits).
 *   - Add atomic write helper (write to .tmp, rename) so MCP server kill
 *     mid-flush never corrupts user-prefs.json.
 *   - Add file-lock so two parallel MCP servers (Cursor + Claude Code on same
 *     mac) don't race on user-prefs.json — `proper-lockfile` candidate.
 *   - Add migration: rules-v1.json → rules-v2.json when contract version bumps.
 */
import { type UserPreferences } from './_vendored-contracts/beacon-mcp-tools-v1.js';
export declare const BEACON_HOME: string;
export declare const RULES_FILE: string;
export declare const USER_PREFS_FILE: string;
export declare const SESSION_CACHE_DB: string;
export declare const SAVINGS_LEDGER_FILE: string;
export declare const DEFAULT_USER_PREFERENCES: UserPreferences;
export interface CachedRulesEnvelope {
    /** ISO 8601 timestamp at which rules were fetched from brain */
    fetchedAt: string;
    /** Brain-issued rule revision */
    revision: number;
    /** Opaque rule blob — schema owned by beacon-rule-protocol-v1 (Week 5) */
    rules: Record<string, unknown>;
}
export declare function loadRules(): CachedRulesEnvelope | null;
export declare function saveRules(envelope: CachedRulesEnvelope): void;
export declare function loadPrefs(): UserPreferences;
export declare function savePrefs(prefs: UserPreferences): void;
/**
 * Phase 0 stub — returns a hand-rolled in-memory map. Week 5 will swap to
 * better-sqlite3. The shape is intentionally minimal so callers can be
 * rewritten without changing call sites.
 */
export interface SessionCacheHandle {
    /** Returns true if the same suggestion fired within the dedupe window. */
    hasRecentSuggestion(key: string, withinMs: number): boolean;
    recordSuggestion(key: string): void;
    /** Number of suggestions emitted in the current session (for maxPerSession). */
    sessionCount(): number;
    reset(): void;
}
export declare function openSessionCache(): SessionCacheHandle;
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