/**
 * HMR-Safe Singleton Helper
 *
 * Creates singletons that persist across Next.js Hot Module Replacement (HMR).
 * Uses globalThis to store state so it survives code reloads in development.
 *
 * @example Core initialization
 * ```typescript
 * import { createHmrSafeSingleton } from '@plyaz/core/utils';
 * import { Core, backendConfig } from '@plyaz/core/backend';
 *
 * export const getServerCore = createHmrSafeSingleton('core', async () => {
 *   await Core.initialize(backendConfig);
 *   return Core;
 * });
 *
 * // Usage in API routes
 * export async function GET() {
 *   const core = await getServerCore();
 *   // core.db, core.cache, etc.
 * }
 * ```
 *
 * @example Database connection
 * ```typescript
 * import { createHmrSafeSingleton } from '@plyaz/core/utils';
 * import { drizzle } from 'drizzle-orm/postgres-js';
 * import postgres from 'postgres';
 *
 * export const getDb = createHmrSafeSingleton('db', async () => {
 *   const client = postgres(process.env.DATABASE_URL);
 *   return drizzle(client);
 * });
 * ```
 *
 * @example Cache client
 * ```typescript
 * import { createHmrSafeSingleton } from '@plyaz/core/utils';
 * import Redis from 'ioredis';
 *
 * export const getRedis = createHmrSafeSingleton('redis', async () => {
 *   return new Redis(process.env.REDIS_URL);
 * });
 * ```
 */
import type { HmrSingletonOptions, HmrSingletonAccessor } from '@plyaz/types/core';
export type { HmrSingletonOptions, HmrSingletonAccessor } from '@plyaz/types/core';
/**
 * Create an HMR-safe singleton accessor.
 *
 * The singleton will persist across Next.js Hot Module Replacement in development,
 * preventing re-initialization on every code change.
 *
 * @param key - Unique key for this singleton (e.g., 'core', 'db', 'redis')
 * @param initializer - Async function that creates the singleton instance
 * @param options - Optional callbacks for lifecycle events
 * @returns Accessor function and utilities
 *
 * @example
 * ```typescript
 * import { createHmrSafeSingleton } from '@plyaz/core/utils';
 *
 * const getCore = createHmrSafeSingleton('core', async () => {
 *   await Core.initialize(config);
 *   return Core;
 * });
 *
 * // In your API route or server component:
 * const core = await getCore();
 *
 * // Check if initialized:
 * if (getCore.isInitialized()) {
 *   // Already initialized
 * }
 *
 * // Reset (for testing):
 * await getCore.reset();
 * ```
 */
export declare function createHmrSafeSingleton<T>(key: string, initializer: () => Promise<T>, options?: HmrSingletonOptions): HmrSingletonAccessor<T>;
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