import type { Plugin } from 'payload';
/**
 * Cloudflare R2 media storage — configured from environment variables (agency
 * infrastructure, not per-project panel data). R2 is S3-compatible, so we use
 * @payloadcms/storage-s3 pointed at the R2 endpoint.
 *
 * Storage is infrastructure (like the database or PAYLOAD_SECRET): it binds at
 * boot, and its credentials are agency-owned — so it lives in .env, not the
 * panel. See docs/storage.md for the required variables.
 *
 * Returns the storage plugin when all R2 vars are present; otherwise returns a
 * no-op passthrough so the project falls back to Payload's default local disk
 * storage (useful in dev without R2). This mirrors how mailAdapter degrades
 * gracefully when a transport isn't configured.
 *
 * @param collections - slugs of upload collections to offload to R2 (e.g. ['media'])
 */
export declare const buildR2Storage: (collections?: string[]) => Plugin;