/** Factory matching ts-validation's `v.string()` / `v.number()` style. */
export declare function file(): FileValidator;
/**
 * `schema.file()` — chainable validator for uploaded files
 * (stacksjs/stacks#1856).
 *
 * Mirrors the ergonomics of `schema.string()` / `schema.number()` /
 * `schema.enum()` from ts-validation but targets the `UploadedFile`
 * shape that `req.file('avatar')` / `req.files` return. Conforms to the
 * `{ rule: { validate(value): { valid, errors? } } }` contract that the
 * Action layer ({@link `@stacksjs/router`} → `validateActionInput`)
 * iterates, so file validations slot into the same `validations:` block
 * as the rest of the field rules:
 *
 * @example
 * ```ts
 * new Action({
 *   method: 'POST',
 *   validations: {
 *     avatar: { rule: schema.file().image().maxBytes(2 * 1024 * 1024) },
 *   },
 *   async handle(req) {
 *     const file = req.file('avatar')!
 *     const { url } = await Storage.put(file, { disk: 'public', dir: 'avatars' })
 *     // …
 *   },
 * })
 * ```
 *
 * The validator is intentionally narrow on the input it accepts: a
 * structural shape with `size: number` and either `mimetype` or
 * `mimeType`, optionally with `originalName` / `name`. Both the
 * router's wrapping `UploadedFile` class and the raw multipart-parse
 * shape satisfy it.
 */
/** Shape this validator runs against. */
export declare interface FileLike {
  size: number
  mimetype?: string
  mimeType?: string
  originalName?: string
  name?: string
}
declare interface ValidationError { message: string }
declare interface ValidationResult { valid: boolean, errors?: ValidationError[] }
/**
 * Chainable file validator. Each method returns `this` so callers can
 * stack constraints in any order; rules accumulate into an internal
 * list and run sequentially on `.validate()`.
 *
 * Designed to be cheap to construct — most validators in an Action's
 * `validations:` block are built once at module load. No I/O happens
 * here; image dimension / content-sniffing rules belong in a separate
 * `@stacksjs/storage/image` opt-in (deliverable 5 of #1856).
 */
export declare class FileValidator {
  required(): this;
  image(): this;
  mimeTypes(allowed: string[]): this;
  maxBytes(max: number): this;
  minBytes(min: number): this;
  extensions(allowed: string[]): this;
  custom(rule: (file: FileLike) => string | null): this;
  validate(value: unknown): ValidationResult;
}