/**
 * Web chat media uploads — same on-disk convention as IM adapters so
 * agents can Read `[图片附件：…]` / `[文件附件：…]` markers.
 *
 * Files land under `~/.agim/media/web/<safeThreadId>/`.
 */
export declare const WEB_MEDIA_MAX_BYTES: number;
export declare function getWebMediaRoot(): string;
export interface SavedWebMedia {
    path: string;
    bytes: number;
    mime: string;
    name: string;
    kind: 'image' | 'file';
}
export declare function saveWebChatMedia(opts: {
    threadId: string;
    filename: string;
    mime: string;
    body: Buffer;
}): Promise<SavedWebMedia>;
export declare function formatMediaMarker(saved: SavedWebMedia): string;
/**
 * Resolve a media path for GET /api/chat/media/file.
 * Lexical resolve + realpath (symlink escape) must stay under a media root.
 * When `threadId` is provided, path must live under `…/web/<sanitized>/`.
 */
export declare function resolveSafeWebMediaPath(requested: string, opts?: {
    threadId?: string;
}): string | null;
/** Async variant used when callers already await (tests / future). */
export declare function resolveSafeWebMediaPathAsync(requested: string, opts?: {
    threadId?: string;
}): Promise<string | null>;
/** Guess a Content-Type from filename when the on-disk mime is unknown.
 *  HTML / SVG / XML are never served as their native types — browsers
 *  would execute them as a stored XSS when Content-Disposition is inline. */
export declare function guessMediaContentType(filename: string): string;
/** True when the file must not be rendered inline by the browser. */
export declare function isUnsafeInlineMedia(filename: string): boolean;
export declare function mediaContentDisposition(filename: string): string;
/** Replay headers that block MIME sniffing and script execution. */
export declare const MEDIA_SAFE_HEADERS: Record<string, string>;
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