import type { ContentBlock, ImageBlock } from '../types/blocks.js';
/**
 * Wire shape for one image attached to a WebUI `user_message`. `data` may be
 * a bare base64 string or a full `data:` URL (the client normally strips the
 * prefix, but legacy senders shipped the whole URL).
 */
export interface IncomingImagePayload {
    data: string;
    mediaType?: string | undefined;
    /** Original filename, when the image came from a file picker or drop. */
    name?: string | undefined;
}
export declare const MAX_INCOMING_IMAGES = 8;
/**
 * Decoded-byte cap per image. The WebUI client downscales before sending, so
 * anything larger than this is either a bypassed client or an abuse attempt.
 * Kept under the servers' WS maxPayload once base64 overhead (~4/3) and the
 * surrounding JSON envelope are added.
 */
export declare const MAX_INCOMING_IMAGE_BYTES: number;
/** Validation failure on user-supplied image payloads. The message is safe to
 *  echo back to the client verbatim. */
export declare class IncomingImageError extends Error {
    constructor(message: string);
}
/**
 * Validate and normalize the `images` field of a `user_message` payload into
 * canonical {@link ImageBlock}s. Accepts the legacy single `imageBase64`
 * field (a data-URL) as a trailing entry so old clients keep working.
 *
 * Throws {@link IncomingImageError} on count/size/media-type violations.
 */
export declare function parseIncomingImages(images?: readonly IncomingImagePayload[] | undefined, legacyImageBase64?: string | undefined): ImageBlock[];
/**
 * Assemble the agent input for a user message that carries images: image
 * blocks first (the order vision providers prefer), then the text block.
 */
export declare function buildUserContentBlocks(text: string, images: readonly ImageBlock[]): ContentBlock[];
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