import type { AssetRecord } from "./wire.js";
/** Where downloads land, relative to the project root. */
export declare const DOWNLOAD_DIR: string;
/**
 * Slugify a subject for use in a filename.
 *
 * Everything outside [a-z0-9-] is dropped rather than escaped, which removes `/`,
 * `\`, `.` and `%` as a class instead of enumerating them. A subject that reduces
 * to nothing yields "asset", so the filename never starts with the separator or
 * collapses into the extension.
 */
export declare function safeSubject(subject: string | undefined): string;
/** The extension, from `format` — admitted only as png/webp, else png. */
export declare function safeExt(format: string | undefined): string;
/**
 * `<subject>-<id>.<ext>`, e.g. `pumpkin-lib_7f3a2c67d4e5b6a7.png`.
 *
 * Throws when `id` is not id-shaped. The id is the one component that could carry
 * a separator if a compromised or drifted API returned something unexpected, and a
 * throw here is strictly better than composing a path from it: the id has ALREADY
 * been validated against the same regex on the way in, so a failure means the wire
 * disagrees with the contract and writing anything at that point is guesswork.
 */
export declare function downloadFilename(a: AssetRecord): string;
/**
 * The absolute path a record downloads to, under `dir`.
 *
 * The join is re-checked against the resolved base: even with a validated filename,
 * asserting containment is one line and it is the assertion that stays true if
 * someone later relaxes downloadFilename.
 */
export declare function downloadPath(baseDir: string, a: AssetRecord): string;
export interface WriteResult {
    path: string;
    bytes: number;
}
/** Does the file already exist? (Used for the refuse-to-overwrite gate.) */
export declare function exists(p: string): Promise<boolean>;
export declare function writeAsset(p: string, bytes: Uint8Array): Promise<WriteResult>;
/**
 * The overwrite refusal names the INTERESTING reason, not "file exists": B37 means
 * the bytes at a library URL never change, so the copy on disk is already identical
 * and re-downloading achieves nothing. That teaches immutability in passing and is
 * more useful than a bare flag suggestion.
 */
export declare function overwriteRefusalLines(relPath: string): string[];